linux/ipc/msg.c

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 14:07:57 +00:00
// SPDX-License-Identifier: GPL-2.0
/*
* linux/ipc/msg.c
* Copyright (C) 1992 Krishna Balasubramanian
*
* Removed all the remaining kerneld mess
* Catch the -EFAULT stuff properly
* Use GFP_KERNEL for messages as in 1.2
* Fixed up the unchecked user space derefs
* Copyright (C) 1998 Alan Cox & Andi Kleen
*
* /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
*
* mostly rewritten, threaded and wake-one semantics added
* MSGMAX limit removed, sysctl's added
* (c) 1999 Manfred Spraul <manfred@colorfullife.com>
[PATCH] Rework of IPC auditing 1) The audit_ipc_perms() function has been split into two different functions: - audit_ipc_obj() - audit_ipc_set_perm() There's a key shift here... The audit_ipc_obj() collects the uid, gid, mode, and SElinux context label of the current ipc object. This audit_ipc_obj() hook is now found in several places. Most notably, it is hooked in ipcperms(), which is called in various places around the ipc code permforming a MAC check. Additionally there are several places where *checkid() is used to validate that an operation is being performed on a valid object while not necessarily having a nearby ipcperms() call. In these locations, audit_ipc_obj() is called to ensure that the information is captured by the audit system. The audit_set_new_perm() function is called any time the permissions on the ipc object changes. In this case, the NEW permissions are recorded (and note that an audit_ipc_obj() call exists just a few lines before each instance). 2) Support for an AUDIT_IPC_SET_PERM audit message type. This allows for separate auxiliary audit records for normal operations on an IPC object and permissions changes. Note that the same struct audit_aux_data_ipcctl is used and populated, however there are separate audit_log_format statements based on the type of the message. Finally, the AUDIT_IPC block of code in audit_free_aux() was extended to handle aux messages of this new type. No more mem leaks I hope ;-) Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2006-04-02 21:07:33 +00:00
*
* support for audit of ipc object properties and permission changes
* Dustin Kirkland <dustin.kirkland@us.ibm.com>
*
* namespaces support
* OpenVZ, SWsoft Inc.
* Pavel Emelianov <xemul@openvz.org>
*/
#include <linux/capability.h>
#include <linux/msg.h>
#include <linux/spinlock.h>
#include <linux/init.h>
ipc: scale msgmni to the amount of lowmem On large systems we'd like to allow a larger number of message queues. In some cases up to 32K. However simply setting MSGMNI to a larger value may cause problems for smaller systems. The first patch of this series introduces a default maximum number of message queue ids that scales with the amount of lowmem. Since msgmni is per namespace and there is no amount of memory dedicated to each namespace so far, the second patch of this series scales msgmni to the number of ipc namespaces too. Since msgmni depends on the amount of memory, it becomes necessary to recompute it upon memory add/remove. In the 4th patch, memory hotplug management is added: a notifier block is registered into the memory hotplug notifier chain for the ipc subsystem. Since the ipc namespaces are not linked together, they have their own notification chain: one notifier_block is defined per ipc namespace. Each time an ipc namespace is created (removed) it registers (unregisters) its notifier block in (from) the ipcns chain. The callback routine registered in the memory chain invokes the ipcns notifier chain with the IPCNS_MEMCHANGE event. Each callback routine registered in the ipcns namespace, in turn, recomputes msgmni for the owning namespace. The 5th patch makes it possible to keep the memory hotplug notifier chain's lock for a lesser amount of time: instead of directly notifying the ipcns notifier chain upon memory add/remove, a work item is added to the global workqueue. When activated, this work item is the one who notifies the ipcns notifier chain. Since msgmni depends on the number of ipc namespaces, it becomes necessary to recompute it upon ipc namespace creation / removal. The 6th patch uses the ipc namespace notifier chain for that purpose: that chain is notified each time an ipc namespace is created or removed. This makes it possible to recompute msgmni for all the namespaces each time one of them is created or removed. When msgmni is explicitely set from userspace, we should avoid recomputing it upon memory add/remove or ipcns creation/removal. This is what the 7th patch does: it simply unregisters the ipcns callback routine as soon as msgmni has been changed from procfs or sysctl(). Even if msgmni is set by hand, it should be possible to make it back automatically recomputed upon memory add/remove or ipcns creation/removal. This what is achieved in patch 8: if set to a negative value, msgmni is added back to the ipcns notifier chain, making it automatically recomputed again. This patch: Compute msg_ctlmni to make it scale with the amount of lowmem. msg_ctlmni is now set to make the message queues occupy 1/32 of the available lowmem. Some cleaning has also been done for the MSGPOOL constant: the msgctl man page says it's not used, but it also defines it as a size in bytes (the code expresses it in Kbytes). Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net> Cc: Yasunori Goto <y-goto@jp.fujitsu.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Mingming Cao <cmm@us.ibm.com> Cc: Pierre Peiffer <pierre.peiffer@bull.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-29 08:00:39 +00:00
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/list.h>
#include <linux/security.h>
#include <linux/sched/wake_q.h>
#include <linux/syscalls.h>
#include <linux/audit.h>
#include <linux/seq_file.h>
#include <linux/rwsem.h>
#include <linux/nsproxy.h>
namespaces: move the IPC namespace under IPC_NS option Currently the IPC namespace management code is spread over the ipc/*.c files. I moved this code into ipc/namespace.c file which is compiled out when needed. The linux/ipc_namespace.h file is used to store the prototypes of the functions in namespace.c and the stubs for NAMESPACES=n case. This is done so, because the stub for copy_ipc_namespace requires the knowledge of the CLONE_NEWIPC flag, which is in sched.h. But the linux/ipc.h file itself in included into many many .c files via the sys.h->sem.h sequence so adding the sched.h into it will make all these .c depend on sched.h which is not that good. On the other hand the knowledge about the namespaces stuff is required in 4 .c files only. Besides, this patch compiles out some auxiliary functions from ipc/sem.c, msg.c and shm.c files. It turned out that moving these functions into namespaces.c is not that easy because they use many other calls and macros from the original file. Moving them would make this patch complicated. On the other hand all these functions can be consolidated, so I will send a separate patch doing this a bit later. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Kirill Korotaev <dev@sw.ru> Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-08 12:18:22 +00:00
#include <linux/ipc_namespace.h>
#include <asm/current.h>
#include <linux/uaccess.h>
#include "util.h"
/* one msq_queue structure for each present queue on the system */
struct msg_queue {
struct kern_ipc_perm q_perm;
time64_t q_stime; /* last msgsnd time */
time64_t q_rtime; /* last msgrcv time */
time64_t q_ctime; /* last change time */
unsigned long q_cbytes; /* current number of bytes on queue */
unsigned long q_qnum; /* number of messages in queue */
unsigned long q_qbytes; /* max number of bytes on queue */
ipc/msg: Fix msgctl(..., IPC_STAT, ...) between pid namespaces Today msg_lspid and msg_lrpid are remembered in the pid namespace of the creator and the processes that last send or received a sysvipc message. If you have processes in multiple pid namespaces that is just wrong. The process ids reported will not make the least bit of sense. This fix is slightly more susceptible to a performance problem than the related fix for System V shared memory. By definition the pids are updated by msgsnd and msgrcv, the fast path of System V message queues. The only concern over the previous implementation is the incrementing and decrementing of the pid reference count. As that is the only difference and multiple updates by of the task_tgid by threads in the same process have been shown in af_unix sockets to create a cache line ping-pong between cpus of the same processor. In this case I don't expect cache lines holding pid reference counts to ping pong between cpus. As senders and receivers update different pids there is a natural separation there. Further if multiple threads of the same process either send or receive messages the pid will be updated to the same value and ipc_update_pid will avoid the reference count update. Which means in the common case I expect msg_lspid and msg_lrpid to remain constant, and reference counts not to be updated when messages are sent. In rare cases it may be possible to trigger the issue which was observed for af_unix sockets, but it will require multiple processes with multiple threads to be either sending or receiving messages. It just does not feel likely that anyone would do that in practice. This change updates msgctl(..., IPC_STAT, ...) to return msg_lspid and msg_lrpid in the pid namespace of the process calling stat. This change also updates cat /proc/sysvipc/msg to return print msg_lspid and msg_lrpid in the pid namespace of the process that opened the proc file. Fixes: b488893a390e ("pid namespaces: changes to show virtual ids to user") Reviewed-by: Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-03-23 05:42:21 +00:00
struct pid *q_lspid; /* pid of last msgsnd */
struct pid *q_lrpid; /* last receive pid */
struct list_head q_messages;
struct list_head q_receivers;
struct list_head q_senders;
} __randomize_layout;
/* one msg_receiver structure for each sleeping receiver */
struct msg_receiver {
struct list_head r_list;
struct task_struct *r_tsk;
int r_mode;
long r_msgtype;
long r_maxsize;
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
struct msg_msg *r_msg;
};
/* one msg_sender for each sleeping sender */
struct msg_sender {
struct list_head list;
struct task_struct *tsk;
ipc/msg: avoid waking sender upon full queue Blocked tasks queued in q_senders waiting for their message to fit in the queue are blindly awoken every time we think there's a remote chance this might happen. This could cause numerous (and expensive -- thundering herd-ish) bogus wakeups if the queue is still really full. Adding to the scheduling cost/overhead, there's also the fact that we need to take the ipc object lock and requeue ourselves in the q_senders list. By keeping track of the blocked sender's message size, we can know previously if the wakeup ought to occur or not. Otherwise, to maintain the current wakeup order we just move it to the tail. This is exactly what occurs right now if the sender needs to go back to sleep. The case of EIDRM is left completely untouched, as we need to wakeup all the tasks, and shouldn't be playing games in the first place. This patch was seen to save on the 'msgctl10' ltp testcase ~15% in context switches (avg out of ten runs). Although these tests are really about functionality (as opposed to performance), is does show the direct benefits of the optimization. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1469748819-19484-6-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:55:02 +00:00
size_t msgsz;
};
#define SEARCH_ANY 1
#define SEARCH_EQUAL 2
#define SEARCH_NOTEQUAL 3
#define SEARCH_LESSEQUAL 4
#define SEARCH_NUMBER 5
#define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS])
static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
{
struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id);
if (IS_ERR(ipcp))
return ERR_CAST(ipcp);
return container_of(ipcp, struct msg_queue, q_perm);
}
static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
int id)
{
struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
if (IS_ERR(ipcp))
return ERR_CAST(ipcp);
return container_of(ipcp, struct msg_queue, q_perm);
}
static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
{
ipc_rmid(&msg_ids(ns), &s->q_perm);
}
ipc: fix race with LSMs Currently, IPC mechanisms do security and auditing related checks under RCU. However, since security modules can free the security structure, for example, through selinux_[sem,msg_queue,shm]_free_security(), we can race if the structure is freed before other tasks are done with it, creating a use-after-free condition. Manfred illustrates this nicely, for instance with shared mem and selinux: -> do_shmat calls rcu_read_lock() -> do_shmat calls shm_object_check(). Checks that the object is still valid - but doesn't acquire any locks. Then it returns. -> do_shmat calls security_shm_shmat (e.g. selinux_shm_shmat) -> selinux_shm_shmat calls ipc_has_perm() -> ipc_has_perm accesses ipc_perms->security shm_close() -> shm_close acquires rw_mutex & shm_lock -> shm_close calls shm_destroy -> shm_destroy calls security_shm_free (e.g. selinux_shm_free_security) -> selinux_shm_free_security calls ipc_free_security(&shp->shm_perm) -> ipc_free_security calls kfree(ipc_perms->security) This patch delays the freeing of the security structures after all RCU readers are done. Furthermore it aligns the security life cycle with that of the rest of IPC - freeing them based on the reference counter. For situations where we need not free security, the current behavior is kept. Linus states: "... the old behavior was suspect for another reason too: having the security blob go away from under a user sounds like it could cause various other problems anyway, so I think the old code was at least _prone_ to bugs even if it didn't have catastrophic behavior." I have tested this patch with IPC testcases from LTP on both my quad-core laptop and on a 64 core NUMA server. In both cases selinux is enabled, and tests pass for both voluntary and forced preemption models. While the mentioned races are theoretical (at least no one as reported them), I wanted to make sure that this new logic doesn't break anything we weren't aware of. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-24 00:04:45 +00:00
static void msg_rcu_free(struct rcu_head *head)
{
struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu);
struct msg_queue *msq = container_of(p, struct msg_queue, q_perm);
ipc: fix race with LSMs Currently, IPC mechanisms do security and auditing related checks under RCU. However, since security modules can free the security structure, for example, through selinux_[sem,msg_queue,shm]_free_security(), we can race if the structure is freed before other tasks are done with it, creating a use-after-free condition. Manfred illustrates this nicely, for instance with shared mem and selinux: -> do_shmat calls rcu_read_lock() -> do_shmat calls shm_object_check(). Checks that the object is still valid - but doesn't acquire any locks. Then it returns. -> do_shmat calls security_shm_shmat (e.g. selinux_shm_shmat) -> selinux_shm_shmat calls ipc_has_perm() -> ipc_has_perm accesses ipc_perms->security shm_close() -> shm_close acquires rw_mutex & shm_lock -> shm_close calls shm_destroy -> shm_destroy calls security_shm_free (e.g. selinux_shm_free_security) -> selinux_shm_free_security calls ipc_free_security(&shp->shm_perm) -> ipc_free_security calls kfree(ipc_perms->security) This patch delays the freeing of the security structures after all RCU readers are done. Furthermore it aligns the security life cycle with that of the rest of IPC - freeing them based on the reference counter. For situations where we need not free security, the current behavior is kept. Linus states: "... the old behavior was suspect for another reason too: having the security blob go away from under a user sounds like it could cause various other problems anyway, so I think the old code was at least _prone_ to bugs even if it didn't have catastrophic behavior." I have tested this patch with IPC testcases from LTP on both my quad-core laptop and on a 64 core NUMA server. In both cases selinux is enabled, and tests pass for both voluntary and forced preemption models. While the mentioned races are theoretical (at least no one as reported them), I wanted to make sure that this new logic doesn't break anything we weren't aware of. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-24 00:04:45 +00:00
security_msg_queue_free(&msq->q_perm);
kvfree(msq);
}
/**
* newque - Create a new msg queue
* @ns: namespace
* @params: ptr to the structure that contains the key and msgflg
*
* Called with msg_ids.rwsem held (writer)
*/
static int newque(struct ipc_namespace *ns, struct ipc_params *params)
{
struct msg_queue *msq;
int retval;
key_t key = params->key;
int msgflg = params->flg;
msq = kvmalloc(sizeof(*msq), GFP_KERNEL);
if (unlikely(!msq))
return -ENOMEM;
msq->q_perm.mode = msgflg & S_IRWXUGO;
msq->q_perm.key = key;
msq->q_perm.security = NULL;
retval = security_msg_queue_alloc(&msq->q_perm);
if (retval) {
kvfree(msq);
return retval;
}
msq->q_stime = msq->q_rtime = 0;
msq->q_ctime = ktime_get_real_seconds();
msq->q_cbytes = msq->q_qnum = 0;
msq->q_qbytes = ns->msg_ctlmnb;
ipc/msg: Fix msgctl(..., IPC_STAT, ...) between pid namespaces Today msg_lspid and msg_lrpid are remembered in the pid namespace of the creator and the processes that last send or received a sysvipc message. If you have processes in multiple pid namespaces that is just wrong. The process ids reported will not make the least bit of sense. This fix is slightly more susceptible to a performance problem than the related fix for System V shared memory. By definition the pids are updated by msgsnd and msgrcv, the fast path of System V message queues. The only concern over the previous implementation is the incrementing and decrementing of the pid reference count. As that is the only difference and multiple updates by of the task_tgid by threads in the same process have been shown in af_unix sockets to create a cache line ping-pong between cpus of the same processor. In this case I don't expect cache lines holding pid reference counts to ping pong between cpus. As senders and receivers update different pids there is a natural separation there. Further if multiple threads of the same process either send or receive messages the pid will be updated to the same value and ipc_update_pid will avoid the reference count update. Which means in the common case I expect msg_lspid and msg_lrpid to remain constant, and reference counts not to be updated when messages are sent. In rare cases it may be possible to trigger the issue which was observed for af_unix sockets, but it will require multiple processes with multiple threads to be either sending or receiving messages. It just does not feel likely that anyone would do that in practice. This change updates msgctl(..., IPC_STAT, ...) to return msg_lspid and msg_lrpid in the pid namespace of the process calling stat. This change also updates cat /proc/sysvipc/msg to return print msg_lspid and msg_lrpid in the pid namespace of the process that opened the proc file. Fixes: b488893a390e ("pid namespaces: changes to show virtual ids to user") Reviewed-by: Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-03-23 05:42:21 +00:00
msq->q_lspid = msq->q_lrpid = NULL;
INIT_LIST_HEAD(&msq->q_messages);
INIT_LIST_HEAD(&msq->q_receivers);
INIT_LIST_HEAD(&msq->q_senders);
/* ipc_addid() locks msq upon success. */
retval = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
if (retval < 0) {
call_rcu(&msq->q_perm.rcu, msg_rcu_free);
return retval;
}
ipc_unlock_object(&msq->q_perm);
rcu_read_unlock();
return msq->q_perm.id;
}
ipc/msg: avoid waking sender upon full queue Blocked tasks queued in q_senders waiting for their message to fit in the queue are blindly awoken every time we think there's a remote chance this might happen. This could cause numerous (and expensive -- thundering herd-ish) bogus wakeups if the queue is still really full. Adding to the scheduling cost/overhead, there's also the fact that we need to take the ipc object lock and requeue ourselves in the q_senders list. By keeping track of the blocked sender's message size, we can know previously if the wakeup ought to occur or not. Otherwise, to maintain the current wakeup order we just move it to the tail. This is exactly what occurs right now if the sender needs to go back to sleep. The case of EIDRM is left completely untouched, as we need to wakeup all the tasks, and shouldn't be playing games in the first place. This patch was seen to save on the 'msgctl10' ltp testcase ~15% in context switches (avg out of ten runs). Although these tests are really about functionality (as opposed to performance), is does show the direct benefits of the optimization. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1469748819-19484-6-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:55:02 +00:00
static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz)
{
return msgsz + msq->q_cbytes <= msq->q_qbytes &&
1 + msq->q_qnum <= msq->q_qbytes;
}
static inline void ss_add(struct msg_queue *msq,
struct msg_sender *mss, size_t msgsz)
{
mss->tsk = current;
ipc/msg: avoid waking sender upon full queue Blocked tasks queued in q_senders waiting for their message to fit in the queue are blindly awoken every time we think there's a remote chance this might happen. This could cause numerous (and expensive -- thundering herd-ish) bogus wakeups if the queue is still really full. Adding to the scheduling cost/overhead, there's also the fact that we need to take the ipc object lock and requeue ourselves in the q_senders list. By keeping track of the blocked sender's message size, we can know previously if the wakeup ought to occur or not. Otherwise, to maintain the current wakeup order we just move it to the tail. This is exactly what occurs right now if the sender needs to go back to sleep. The case of EIDRM is left completely untouched, as we need to wakeup all the tasks, and shouldn't be playing games in the first place. This patch was seen to save on the 'msgctl10' ltp testcase ~15% in context switches (avg out of ten runs). Although these tests are really about functionality (as opposed to performance), is does show the direct benefits of the optimization. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1469748819-19484-6-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:55:02 +00:00
mss->msgsz = msgsz;
__set_current_state(TASK_INTERRUPTIBLE);
list_add_tail(&mss->list, &msq->q_senders);
}
static inline void ss_del(struct msg_sender *mss)
{
ipc/msg: avoid waking sender upon full queue Blocked tasks queued in q_senders waiting for their message to fit in the queue are blindly awoken every time we think there's a remote chance this might happen. This could cause numerous (and expensive -- thundering herd-ish) bogus wakeups if the queue is still really full. Adding to the scheduling cost/overhead, there's also the fact that we need to take the ipc object lock and requeue ourselves in the q_senders list. By keeping track of the blocked sender's message size, we can know previously if the wakeup ought to occur or not. Otherwise, to maintain the current wakeup order we just move it to the tail. This is exactly what occurs right now if the sender needs to go back to sleep. The case of EIDRM is left completely untouched, as we need to wakeup all the tasks, and shouldn't be playing games in the first place. This patch was seen to save on the 'msgctl10' ltp testcase ~15% in context switches (avg out of ten runs). Although these tests are really about functionality (as opposed to performance), is does show the direct benefits of the optimization. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1469748819-19484-6-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:55:02 +00:00
if (mss->list.next)
list_del(&mss->list);
}
ipc/msg: avoid waking sender upon full queue Blocked tasks queued in q_senders waiting for their message to fit in the queue are blindly awoken every time we think there's a remote chance this might happen. This could cause numerous (and expensive -- thundering herd-ish) bogus wakeups if the queue is still really full. Adding to the scheduling cost/overhead, there's also the fact that we need to take the ipc object lock and requeue ourselves in the q_senders list. By keeping track of the blocked sender's message size, we can know previously if the wakeup ought to occur or not. Otherwise, to maintain the current wakeup order we just move it to the tail. This is exactly what occurs right now if the sender needs to go back to sleep. The case of EIDRM is left completely untouched, as we need to wakeup all the tasks, and shouldn't be playing games in the first place. This patch was seen to save on the 'msgctl10' ltp testcase ~15% in context switches (avg out of ten runs). Although these tests are really about functionality (as opposed to performance), is does show the direct benefits of the optimization. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1469748819-19484-6-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:55:02 +00:00
static void ss_wakeup(struct msg_queue *msq,
struct wake_q_head *wake_q, bool kill)
{
struct msg_sender *mss, *t;
ipc/msg: avoid waking sender upon full queue Blocked tasks queued in q_senders waiting for their message to fit in the queue are blindly awoken every time we think there's a remote chance this might happen. This could cause numerous (and expensive -- thundering herd-ish) bogus wakeups if the queue is still really full. Adding to the scheduling cost/overhead, there's also the fact that we need to take the ipc object lock and requeue ourselves in the q_senders list. By keeping track of the blocked sender's message size, we can know previously if the wakeup ought to occur or not. Otherwise, to maintain the current wakeup order we just move it to the tail. This is exactly what occurs right now if the sender needs to go back to sleep. The case of EIDRM is left completely untouched, as we need to wakeup all the tasks, and shouldn't be playing games in the first place. This patch was seen to save on the 'msgctl10' ltp testcase ~15% in context switches (avg out of ten runs). Although these tests are really about functionality (as opposed to performance), is does show the direct benefits of the optimization. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1469748819-19484-6-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:55:02 +00:00
struct task_struct *stop_tsk = NULL;
struct list_head *h = &msq->q_senders;
list_for_each_entry_safe(mss, t, h, list) {
if (kill)
mss->list.next = NULL;
ipc/msg: avoid waking sender upon full queue Blocked tasks queued in q_senders waiting for their message to fit in the queue are blindly awoken every time we think there's a remote chance this might happen. This could cause numerous (and expensive -- thundering herd-ish) bogus wakeups if the queue is still really full. Adding to the scheduling cost/overhead, there's also the fact that we need to take the ipc object lock and requeue ourselves in the q_senders list. By keeping track of the blocked sender's message size, we can know previously if the wakeup ought to occur or not. Otherwise, to maintain the current wakeup order we just move it to the tail. This is exactly what occurs right now if the sender needs to go back to sleep. The case of EIDRM is left completely untouched, as we need to wakeup all the tasks, and shouldn't be playing games in the first place. This patch was seen to save on the 'msgctl10' ltp testcase ~15% in context switches (avg out of ten runs). Although these tests are really about functionality (as opposed to performance), is does show the direct benefits of the optimization. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1469748819-19484-6-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:55:02 +00:00
/*
* Stop at the first task we don't wakeup,
* we've already iterated the original
* sender queue.
*/
else if (stop_tsk == mss->tsk)
break;
/*
* We are not in an EIDRM scenario here, therefore
* verify that we really need to wakeup the task.
* To maintain current semantics and wakeup order,
* move the sender to the tail on behalf of the
* blocked task.
*/
else if (!msg_fits_inqueue(msq, mss->msgsz)) {
if (!stop_tsk)
stop_tsk = mss->tsk;
list_move_tail(&mss->list, &msq->q_senders);
continue;
}
wake_q_add(wake_q, mss->tsk);
}
}
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
static void expunge_all(struct msg_queue *msq, int res,
struct wake_q_head *wake_q)
{
struct msg_receiver *msr, *t;
list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
wake_q_add(wake_q, msr->r_tsk);
WRITE_ONCE(msr->r_msg, ERR_PTR(res));
}
}
/*
* freeque() wakes up waiters on the sender and receiver waiting queue,
* removes the message queue from message queue ID IDR, and cleans up all the
* messages associated with this queue.
*
* msg_ids.rwsem (writer) and the spinlock for this message queue are held
* before freeque() is called. msg_ids.rwsem remains locked on exit.
*/
static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
{
struct msg_msg *msg, *t;
struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
DEFINE_WAKE_Q(wake_q);
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
expunge_all(msq, -EIDRM, &wake_q);
ipc/msg: avoid waking sender upon full queue Blocked tasks queued in q_senders waiting for their message to fit in the queue are blindly awoken every time we think there's a remote chance this might happen. This could cause numerous (and expensive -- thundering herd-ish) bogus wakeups if the queue is still really full. Adding to the scheduling cost/overhead, there's also the fact that we need to take the ipc object lock and requeue ourselves in the q_senders list. By keeping track of the blocked sender's message size, we can know previously if the wakeup ought to occur or not. Otherwise, to maintain the current wakeup order we just move it to the tail. This is exactly what occurs right now if the sender needs to go back to sleep. The case of EIDRM is left completely untouched, as we need to wakeup all the tasks, and shouldn't be playing games in the first place. This patch was seen to save on the 'msgctl10' ltp testcase ~15% in context switches (avg out of ten runs). Although these tests are really about functionality (as opposed to performance), is does show the direct benefits of the optimization. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1469748819-19484-6-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:55:02 +00:00
ss_wakeup(msq, &wake_q, true);
msg_rmid(ns, msq);
ipc_unlock_object(&msq->q_perm);
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
wake_up_q(&wake_q);
rcu_read_unlock();
list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
atomic_dec(&ns->msg_hdrs);
free_msg(msg);
}
atomic_sub(msq->q_cbytes, &ns->msg_bytes);
ipc/msg: Fix msgctl(..., IPC_STAT, ...) between pid namespaces Today msg_lspid and msg_lrpid are remembered in the pid namespace of the creator and the processes that last send or received a sysvipc message. If you have processes in multiple pid namespaces that is just wrong. The process ids reported will not make the least bit of sense. This fix is slightly more susceptible to a performance problem than the related fix for System V shared memory. By definition the pids are updated by msgsnd and msgrcv, the fast path of System V message queues. The only concern over the previous implementation is the incrementing and decrementing of the pid reference count. As that is the only difference and multiple updates by of the task_tgid by threads in the same process have been shown in af_unix sockets to create a cache line ping-pong between cpus of the same processor. In this case I don't expect cache lines holding pid reference counts to ping pong between cpus. As senders and receivers update different pids there is a natural separation there. Further if multiple threads of the same process either send or receive messages the pid will be updated to the same value and ipc_update_pid will avoid the reference count update. Which means in the common case I expect msg_lspid and msg_lrpid to remain constant, and reference counts not to be updated when messages are sent. In rare cases it may be possible to trigger the issue which was observed for af_unix sockets, but it will require multiple processes with multiple threads to be either sending or receiving messages. It just does not feel likely that anyone would do that in practice. This change updates msgctl(..., IPC_STAT, ...) to return msg_lspid and msg_lrpid in the pid namespace of the process calling stat. This change also updates cat /proc/sysvipc/msg to return print msg_lspid and msg_lrpid in the pid namespace of the process that opened the proc file. Fixes: b488893a390e ("pid namespaces: changes to show virtual ids to user") Reviewed-by: Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-03-23 05:42:21 +00:00
ipc_update_pid(&msq->q_lspid, NULL);
ipc_update_pid(&msq->q_lrpid, NULL);
ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
}
long ksys_msgget(key_t key, int msgflg)
{
struct ipc_namespace *ns;
static const struct ipc_ops msg_ops = {
.getnew = newque,
.associate = security_msg_queue_associate,
};
struct ipc_params msg_params;
ns = current->nsproxy->ipc_ns;
msg_params.key = key;
msg_params.flg = msgflg;
return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
}
SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
{
return ksys_msgget(key, msgflg);
}
static inline unsigned long
copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
{
switch (version) {
case IPC_64:
return copy_to_user(buf, in, sizeof(*in));
case IPC_OLD:
{
struct msqid_ds out;
memset(&out, 0, sizeof(out));
ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
out.msg_stime = in->msg_stime;
out.msg_rtime = in->msg_rtime;
out.msg_ctime = in->msg_ctime;
if (in->msg_cbytes > USHRT_MAX)
out.msg_cbytes = USHRT_MAX;
else
out.msg_cbytes = in->msg_cbytes;
out.msg_lcbytes = in->msg_cbytes;
if (in->msg_qnum > USHRT_MAX)
out.msg_qnum = USHRT_MAX;
else
out.msg_qnum = in->msg_qnum;
if (in->msg_qbytes > USHRT_MAX)
out.msg_qbytes = USHRT_MAX;
else
out.msg_qbytes = in->msg_qbytes;
out.msg_lqbytes = in->msg_qbytes;
out.msg_lspid = in->msg_lspid;
out.msg_lrpid = in->msg_lrpid;
return copy_to_user(buf, &out, sizeof(out));
}
default:
return -EINVAL;
}
}
static inline unsigned long
copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
{
switch (version) {
case IPC_64:
if (copy_from_user(out, buf, sizeof(*out)))
return -EFAULT;
return 0;
case IPC_OLD:
{
struct msqid_ds tbuf_old;
if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
return -EFAULT;
out->msg_perm.uid = tbuf_old.msg_perm.uid;
out->msg_perm.gid = tbuf_old.msg_perm.gid;
out->msg_perm.mode = tbuf_old.msg_perm.mode;
if (tbuf_old.msg_qbytes == 0)
out->msg_qbytes = tbuf_old.msg_lqbytes;
else
out->msg_qbytes = tbuf_old.msg_qbytes;
return 0;
}
default:
return -EINVAL;
}
}
/*
* This function handles some msgctl commands which require the rwsem
* to be held in write mode.
* NOTE: no locks must be held, the rwsem is taken inside this function.
*/
static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
struct msqid64_ds *msqid64)
{
struct kern_ipc_perm *ipcp;
struct msg_queue *msq;
int err;
down_write(&msg_ids(ns).rwsem);
rcu_read_lock();
ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
&msqid64->msg_perm, msqid64->msg_qbytes);
if (IS_ERR(ipcp)) {
err = PTR_ERR(ipcp);
goto out_unlock1;
}
msq = container_of(ipcp, struct msg_queue, q_perm);
err = security_msg_queue_msgctl(&msq->q_perm, cmd);
if (err)
goto out_unlock1;
switch (cmd) {
case IPC_RMID:
ipc_lock_object(&msq->q_perm);
/* freeque unlocks the ipc object and rcu */
freeque(ns, ipcp);
goto out_up;
case IPC_SET:
{
DEFINE_WAKE_Q(wake_q);
if (msqid64->msg_qbytes > ns->msg_ctlmnb &&
!capable(CAP_SYS_RESOURCE)) {
err = -EPERM;
goto out_unlock1;
}
ipc_lock_object(&msq->q_perm);
err = ipc_update_perm(&msqid64->msg_perm, ipcp);
if (err)
goto out_unlock0;
msq->q_qbytes = msqid64->msg_qbytes;
msq->q_ctime = ktime_get_real_seconds();
/*
* Sleeping receivers might be excluded by
* stricter permissions.
*/
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
expunge_all(msq, -EAGAIN, &wake_q);
/*
* Sleeping senders might be able to send
* due to a larger queue size.
*/
ipc/msg: avoid waking sender upon full queue Blocked tasks queued in q_senders waiting for their message to fit in the queue are blindly awoken every time we think there's a remote chance this might happen. This could cause numerous (and expensive -- thundering herd-ish) bogus wakeups if the queue is still really full. Adding to the scheduling cost/overhead, there's also the fact that we need to take the ipc object lock and requeue ourselves in the q_senders list. By keeping track of the blocked sender's message size, we can know previously if the wakeup ought to occur or not. Otherwise, to maintain the current wakeup order we just move it to the tail. This is exactly what occurs right now if the sender needs to go back to sleep. The case of EIDRM is left completely untouched, as we need to wakeup all the tasks, and shouldn't be playing games in the first place. This patch was seen to save on the 'msgctl10' ltp testcase ~15% in context switches (avg out of ten runs). Although these tests are really about functionality (as opposed to performance), is does show the direct benefits of the optimization. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1469748819-19484-6-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:55:02 +00:00
ss_wakeup(msq, &wake_q, false);
ipc_unlock_object(&msq->q_perm);
wake_up_q(&wake_q);
goto out_unlock1;
}
default:
err = -EINVAL;
goto out_unlock1;
}
out_unlock0:
ipc_unlock_object(&msq->q_perm);
out_unlock1:
rcu_read_unlock();
out_up:
up_write(&msg_ids(ns).rwsem);
return err;
}
static int msgctl_info(struct ipc_namespace *ns, int msqid,
int cmd, struct msginfo *msginfo)
{
int err;
int max_id;
/*
* We must not return kernel stack data.
* due to padding, it's not enough
* to set all member fields.
*/
err = security_msg_queue_msgctl(NULL, cmd);
if (err)
return err;
memset(msginfo, 0, sizeof(*msginfo));
msginfo->msgmni = ns->msg_ctlmni;
msginfo->msgmax = ns->msg_ctlmax;
msginfo->msgmnb = ns->msg_ctlmnb;
msginfo->msgssz = MSGSSZ;
msginfo->msgseg = MSGSEG;
down_read(&msg_ids(ns).rwsem);
if (cmd == MSG_INFO) {
msginfo->msgpool = msg_ids(ns).in_use;
msginfo->msgmap = atomic_read(&ns->msg_hdrs);
msginfo->msgtql = atomic_read(&ns->msg_bytes);
} else {
msginfo->msgmap = MSGMAP;
msginfo->msgpool = MSGPOOL;
msginfo->msgtql = MSGTQL;
}
max_id = ipc_get_maxid(&msg_ids(ns));
up_read(&msg_ids(ns).rwsem);
return (max_id < 0) ? 0 : max_id;
}
static int msgctl_stat(struct ipc_namespace *ns, int msqid,
int cmd, struct msqid64_ds *p)
{
struct msg_queue *msq;
int id = 0;
int err;
memset(p, 0, sizeof(*p));
rcu_read_lock();
ipc/msg: introduce msgctl(MSG_STAT_ANY) There is a permission discrepancy when consulting msq ipc object metadata between /proc/sysvipc/msg (0444) and the MSG_STAT shmctl command. The later does permission checks for the object vs S_IRUGO. As such there can be cases where EACCESS is returned via syscall but the info is displayed anyways in the procfs files. While this might have security implications via info leaking (albeit no writing to the msq metadata), this behavior goes way back and showing all the objects regardless of the permissions was most likely an overlook - so we are stuck with it. Furthermore, modifying either the syscall or the procfs file can cause userspace programs to break (ie ipcs). Some applications require getting the procfs info (without root privileges) and can be rather slow in comparison with a syscall -- up to 500x in some reported cases for shm. This patch introduces a new MSG_STAT_ANY command such that the msq ipc object permissions are ignored, and only audited instead. In addition, I've left the lsm security hook checks in place, as if some policy can block the call, then the user has no other choice than just parsing the procfs file. Link: http://lkml.kernel.org/r/20180215162458.10059-4-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Reported-by: Robert Kettler <robert.kettler@outlook.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kees Cook <keescook@chromium.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-10 23:35:30 +00:00
if (cmd == MSG_STAT || cmd == MSG_STAT_ANY) {
msq = msq_obtain_object(ns, msqid);
if (IS_ERR(msq)) {
err = PTR_ERR(msq);
goto out_unlock;
}
id = msq->q_perm.id;
ipc/msg: introduce msgctl(MSG_STAT_ANY) There is a permission discrepancy when consulting msq ipc object metadata between /proc/sysvipc/msg (0444) and the MSG_STAT shmctl command. The later does permission checks for the object vs S_IRUGO. As such there can be cases where EACCESS is returned via syscall but the info is displayed anyways in the procfs files. While this might have security implications via info leaking (albeit no writing to the msq metadata), this behavior goes way back and showing all the objects regardless of the permissions was most likely an overlook - so we are stuck with it. Furthermore, modifying either the syscall or the procfs file can cause userspace programs to break (ie ipcs). Some applications require getting the procfs info (without root privileges) and can be rather slow in comparison with a syscall -- up to 500x in some reported cases for shm. This patch introduces a new MSG_STAT_ANY command such that the msq ipc object permissions are ignored, and only audited instead. In addition, I've left the lsm security hook checks in place, as if some policy can block the call, then the user has no other choice than just parsing the procfs file. Link: http://lkml.kernel.org/r/20180215162458.10059-4-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Reported-by: Robert Kettler <robert.kettler@outlook.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kees Cook <keescook@chromium.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-10 23:35:30 +00:00
} else { /* IPC_STAT */
msq = msq_obtain_object_check(ns, msqid);
if (IS_ERR(msq)) {
err = PTR_ERR(msq);
goto out_unlock;
}
}
ipc/msg: introduce msgctl(MSG_STAT_ANY) There is a permission discrepancy when consulting msq ipc object metadata between /proc/sysvipc/msg (0444) and the MSG_STAT shmctl command. The later does permission checks for the object vs S_IRUGO. As such there can be cases where EACCESS is returned via syscall but the info is displayed anyways in the procfs files. While this might have security implications via info leaking (albeit no writing to the msq metadata), this behavior goes way back and showing all the objects regardless of the permissions was most likely an overlook - so we are stuck with it. Furthermore, modifying either the syscall or the procfs file can cause userspace programs to break (ie ipcs). Some applications require getting the procfs info (without root privileges) and can be rather slow in comparison with a syscall -- up to 500x in some reported cases for shm. This patch introduces a new MSG_STAT_ANY command such that the msq ipc object permissions are ignored, and only audited instead. In addition, I've left the lsm security hook checks in place, as if some policy can block the call, then the user has no other choice than just parsing the procfs file. Link: http://lkml.kernel.org/r/20180215162458.10059-4-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Reported-by: Robert Kettler <robert.kettler@outlook.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kees Cook <keescook@chromium.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-10 23:35:30 +00:00
/* see comment for SHM_STAT_ANY */
if (cmd == MSG_STAT_ANY)
audit_ipc_obj(&msq->q_perm);
else {
err = -EACCES;
if (ipcperms(ns, &msq->q_perm, S_IRUGO))
goto out_unlock;
}
err = security_msg_queue_msgctl(&msq->q_perm, cmd);
if (err)
goto out_unlock;
ipc_lock_object(&msq->q_perm);
if (!ipc_valid_object(&msq->q_perm)) {
ipc_unlock_object(&msq->q_perm);
err = -EIDRM;
goto out_unlock;
}
kernel_to_ipc64_perm(&msq->q_perm, &p->msg_perm);
p->msg_stime = msq->q_stime;
p->msg_rtime = msq->q_rtime;
p->msg_ctime = msq->q_ctime;
p->msg_cbytes = msq->q_cbytes;
p->msg_qnum = msq->q_qnum;
p->msg_qbytes = msq->q_qbytes;
ipc/msg: Fix msgctl(..., IPC_STAT, ...) between pid namespaces Today msg_lspid and msg_lrpid are remembered in the pid namespace of the creator and the processes that last send or received a sysvipc message. If you have processes in multiple pid namespaces that is just wrong. The process ids reported will not make the least bit of sense. This fix is slightly more susceptible to a performance problem than the related fix for System V shared memory. By definition the pids are updated by msgsnd and msgrcv, the fast path of System V message queues. The only concern over the previous implementation is the incrementing and decrementing of the pid reference count. As that is the only difference and multiple updates by of the task_tgid by threads in the same process have been shown in af_unix sockets to create a cache line ping-pong between cpus of the same processor. In this case I don't expect cache lines holding pid reference counts to ping pong between cpus. As senders and receivers update different pids there is a natural separation there. Further if multiple threads of the same process either send or receive messages the pid will be updated to the same value and ipc_update_pid will avoid the reference count update. Which means in the common case I expect msg_lspid and msg_lrpid to remain constant, and reference counts not to be updated when messages are sent. In rare cases it may be possible to trigger the issue which was observed for af_unix sockets, but it will require multiple processes with multiple threads to be either sending or receiving messages. It just does not feel likely that anyone would do that in practice. This change updates msgctl(..., IPC_STAT, ...) to return msg_lspid and msg_lrpid in the pid namespace of the process calling stat. This change also updates cat /proc/sysvipc/msg to return print msg_lspid and msg_lrpid in the pid namespace of the process that opened the proc file. Fixes: b488893a390e ("pid namespaces: changes to show virtual ids to user") Reviewed-by: Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-03-23 05:42:21 +00:00
p->msg_lspid = pid_vnr(msq->q_lspid);
p->msg_lrpid = pid_vnr(msq->q_lrpid);
ipc_unlock_object(&msq->q_perm);
rcu_read_unlock();
return id;
out_unlock:
rcu_read_unlock();
return err;
}
long ksys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
{
int version;
struct ipc_namespace *ns;
struct msqid64_ds msqid64;
int err;
if (msqid < 0 || cmd < 0)
return -EINVAL;
version = ipc_parse_version(&cmd);
ns = current->nsproxy->ipc_ns;
switch (cmd) {
case IPC_INFO:
case MSG_INFO: {
struct msginfo msginfo;
err = msgctl_info(ns, msqid, cmd, &msginfo);
if (err < 0)
return err;
if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
err = -EFAULT;
return err;
}
case MSG_STAT: /* msqid is an index rather than a msg queue id */
ipc/msg: introduce msgctl(MSG_STAT_ANY) There is a permission discrepancy when consulting msq ipc object metadata between /proc/sysvipc/msg (0444) and the MSG_STAT shmctl command. The later does permission checks for the object vs S_IRUGO. As such there can be cases where EACCESS is returned via syscall but the info is displayed anyways in the procfs files. While this might have security implications via info leaking (albeit no writing to the msq metadata), this behavior goes way back and showing all the objects regardless of the permissions was most likely an overlook - so we are stuck with it. Furthermore, modifying either the syscall or the procfs file can cause userspace programs to break (ie ipcs). Some applications require getting the procfs info (without root privileges) and can be rather slow in comparison with a syscall -- up to 500x in some reported cases for shm. This patch introduces a new MSG_STAT_ANY command such that the msq ipc object permissions are ignored, and only audited instead. In addition, I've left the lsm security hook checks in place, as if some policy can block the call, then the user has no other choice than just parsing the procfs file. Link: http://lkml.kernel.org/r/20180215162458.10059-4-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Reported-by: Robert Kettler <robert.kettler@outlook.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kees Cook <keescook@chromium.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-10 23:35:30 +00:00
case MSG_STAT_ANY:
case IPC_STAT:
err = msgctl_stat(ns, msqid, cmd, &msqid64);
if (err < 0)
return err;
if (copy_msqid_to_user(buf, &msqid64, version))
err = -EFAULT;
return err;
case IPC_SET:
if (copy_msqid_from_user(&msqid64, buf, version))
return -EFAULT;
/* fallthru */
case IPC_RMID:
return msgctl_down(ns, msqid, cmd, &msqid64);
default:
return -EINVAL;
}
}
SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
{
return ksys_msgctl(msqid, cmd, buf);
}
#ifdef CONFIG_COMPAT
struct compat_msqid_ds {
struct compat_ipc_perm msg_perm;
compat_uptr_t msg_first;
compat_uptr_t msg_last;
compat_time_t msg_stime;
compat_time_t msg_rtime;
compat_time_t msg_ctime;
compat_ulong_t msg_lcbytes;
compat_ulong_t msg_lqbytes;
unsigned short msg_cbytes;
unsigned short msg_qnum;
unsigned short msg_qbytes;
compat_ipc_pid_t msg_lspid;
compat_ipc_pid_t msg_lrpid;
};
static int copy_compat_msqid_from_user(struct msqid64_ds *out, void __user *buf,
int version)
{
memset(out, 0, sizeof(*out));
if (version == IPC_64) {
struct compat_msqid64_ds __user *p = buf;
if (get_compat_ipc64_perm(&out->msg_perm, &p->msg_perm))
return -EFAULT;
if (get_user(out->msg_qbytes, &p->msg_qbytes))
return -EFAULT;
} else {
struct compat_msqid_ds __user *p = buf;
if (get_compat_ipc_perm(&out->msg_perm, &p->msg_perm))
return -EFAULT;
if (get_user(out->msg_qbytes, &p->msg_qbytes))
return -EFAULT;
}
return 0;
}
static int copy_compat_msqid_to_user(void __user *buf, struct msqid64_ds *in,
int version)
{
if (version == IPC_64) {
struct compat_msqid64_ds v;
memset(&v, 0, sizeof(v));
to_compat_ipc64_perm(&v.msg_perm, &in->msg_perm);
v.msg_stime = in->msg_stime;
v.msg_rtime = in->msg_rtime;
v.msg_ctime = in->msg_ctime;
v.msg_cbytes = in->msg_cbytes;
v.msg_qnum = in->msg_qnum;
v.msg_qbytes = in->msg_qbytes;
v.msg_lspid = in->msg_lspid;
v.msg_lrpid = in->msg_lrpid;
return copy_to_user(buf, &v, sizeof(v));
} else {
struct compat_msqid_ds v;
memset(&v, 0, sizeof(v));
to_compat_ipc_perm(&v.msg_perm, &in->msg_perm);
v.msg_stime = in->msg_stime;
v.msg_rtime = in->msg_rtime;
v.msg_ctime = in->msg_ctime;
v.msg_cbytes = in->msg_cbytes;
v.msg_qnum = in->msg_qnum;
v.msg_qbytes = in->msg_qbytes;
v.msg_lspid = in->msg_lspid;
v.msg_lrpid = in->msg_lrpid;
return copy_to_user(buf, &v, sizeof(v));
}
}
long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr)
{
struct ipc_namespace *ns;
int err;
struct msqid64_ds msqid64;
int version = compat_ipc_parse_version(&cmd);
ns = current->nsproxy->ipc_ns;
if (msqid < 0 || cmd < 0)
return -EINVAL;
switch (cmd & (~IPC_64)) {
case IPC_INFO:
case MSG_INFO: {
struct msginfo msginfo;
err = msgctl_info(ns, msqid, cmd, &msginfo);
if (err < 0)
return err;
if (copy_to_user(uptr, &msginfo, sizeof(struct msginfo)))
err = -EFAULT;
return err;
}
case IPC_STAT:
case MSG_STAT:
ipc/msg: introduce msgctl(MSG_STAT_ANY) There is a permission discrepancy when consulting msq ipc object metadata between /proc/sysvipc/msg (0444) and the MSG_STAT shmctl command. The later does permission checks for the object vs S_IRUGO. As such there can be cases where EACCESS is returned via syscall but the info is displayed anyways in the procfs files. While this might have security implications via info leaking (albeit no writing to the msq metadata), this behavior goes way back and showing all the objects regardless of the permissions was most likely an overlook - so we are stuck with it. Furthermore, modifying either the syscall or the procfs file can cause userspace programs to break (ie ipcs). Some applications require getting the procfs info (without root privileges) and can be rather slow in comparison with a syscall -- up to 500x in some reported cases for shm. This patch introduces a new MSG_STAT_ANY command such that the msq ipc object permissions are ignored, and only audited instead. In addition, I've left the lsm security hook checks in place, as if some policy can block the call, then the user has no other choice than just parsing the procfs file. Link: http://lkml.kernel.org/r/20180215162458.10059-4-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Reported-by: Robert Kettler <robert.kettler@outlook.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kees Cook <keescook@chromium.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-10 23:35:30 +00:00
case MSG_STAT_ANY:
err = msgctl_stat(ns, msqid, cmd, &msqid64);
if (err < 0)
return err;
if (copy_compat_msqid_to_user(uptr, &msqid64, version))
err = -EFAULT;
return err;
case IPC_SET:
if (copy_compat_msqid_from_user(&msqid64, uptr, version))
return -EFAULT;
/* fallthru */
case IPC_RMID:
return msgctl_down(ns, msqid, cmd, &msqid64);
default:
return -EINVAL;
}
}
COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr)
{
return compat_ksys_msgctl(msqid, cmd, uptr);
}
#endif
static int testmsg(struct msg_msg *msg, long type, int mode)
{
switch (mode) {
case SEARCH_ANY:
case SEARCH_NUMBER:
return 1;
case SEARCH_LESSEQUAL:
if (msg->m_type <= type)
return 1;
break;
case SEARCH_EQUAL:
if (msg->m_type == type)
return 1;
break;
case SEARCH_NOTEQUAL:
if (msg->m_type != type)
return 1;
break;
}
return 0;
}
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg,
struct wake_q_head *wake_q)
{
struct msg_receiver *msr, *t;
list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
!security_msg_queue_msgrcv(&msq->q_perm, msg, msr->r_tsk,
msr->r_msgtype, msr->r_mode)) {
list_del(&msr->r_list);
if (msr->r_maxsize < msg->m_ts) {
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
wake_q_add(wake_q, msr->r_tsk);
WRITE_ONCE(msr->r_msg, ERR_PTR(-E2BIG));
} else {
ipc/msg: Fix msgctl(..., IPC_STAT, ...) between pid namespaces Today msg_lspid and msg_lrpid are remembered in the pid namespace of the creator and the processes that last send or received a sysvipc message. If you have processes in multiple pid namespaces that is just wrong. The process ids reported will not make the least bit of sense. This fix is slightly more susceptible to a performance problem than the related fix for System V shared memory. By definition the pids are updated by msgsnd and msgrcv, the fast path of System V message queues. The only concern over the previous implementation is the incrementing and decrementing of the pid reference count. As that is the only difference and multiple updates by of the task_tgid by threads in the same process have been shown in af_unix sockets to create a cache line ping-pong between cpus of the same processor. In this case I don't expect cache lines holding pid reference counts to ping pong between cpus. As senders and receivers update different pids there is a natural separation there. Further if multiple threads of the same process either send or receive messages the pid will be updated to the same value and ipc_update_pid will avoid the reference count update. Which means in the common case I expect msg_lspid and msg_lrpid to remain constant, and reference counts not to be updated when messages are sent. In rare cases it may be possible to trigger the issue which was observed for af_unix sockets, but it will require multiple processes with multiple threads to be either sending or receiving messages. It just does not feel likely that anyone would do that in practice. This change updates msgctl(..., IPC_STAT, ...) to return msg_lspid and msg_lrpid in the pid namespace of the process calling stat. This change also updates cat /proc/sysvipc/msg to return print msg_lspid and msg_lrpid in the pid namespace of the process that opened the proc file. Fixes: b488893a390e ("pid namespaces: changes to show virtual ids to user") Reviewed-by: Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-03-23 05:42:21 +00:00
ipc_update_pid(&msq->q_lrpid, task_pid(msr->r_tsk));
msq->q_rtime = get_seconds();
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
wake_q_add(wake_q, msr->r_tsk);
WRITE_ONCE(msr->r_msg, msg);
return 1;
}
}
}
return 0;
}
static long do_msgsnd(int msqid, long mtype, void __user *mtext,
size_t msgsz, int msgflg)
{
struct msg_queue *msq;
struct msg_msg *msg;
int err;
struct ipc_namespace *ns;
DEFINE_WAKE_Q(wake_q);
ns = current->nsproxy->ipc_ns;
if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
return -EINVAL;
if (mtype < 1)
return -EINVAL;
msg = load_msg(mtext, msgsz);
if (IS_ERR(msg))
return PTR_ERR(msg);
msg->m_type = mtype;
msg->m_ts = msgsz;
rcu_read_lock();
msq = msq_obtain_object_check(ns, msqid);
if (IS_ERR(msq)) {
err = PTR_ERR(msq);
goto out_unlock1;
}
ipc_lock_object(&msq->q_perm);
for (;;) {
struct msg_sender s;
err = -EACCES;
if (ipcperms(ns, &msq->q_perm, S_IWUGO))
goto out_unlock0;
/* raced with RMID? */
if (!ipc_valid_object(&msq->q_perm)) {
err = -EIDRM;
goto out_unlock0;
}
err = security_msg_queue_msgsnd(&msq->q_perm, msg, msgflg);
if (err)
goto out_unlock0;
ipc/msg: avoid waking sender upon full queue Blocked tasks queued in q_senders waiting for their message to fit in the queue are blindly awoken every time we think there's a remote chance this might happen. This could cause numerous (and expensive -- thundering herd-ish) bogus wakeups if the queue is still really full. Adding to the scheduling cost/overhead, there's also the fact that we need to take the ipc object lock and requeue ourselves in the q_senders list. By keeping track of the blocked sender's message size, we can know previously if the wakeup ought to occur or not. Otherwise, to maintain the current wakeup order we just move it to the tail. This is exactly what occurs right now if the sender needs to go back to sleep. The case of EIDRM is left completely untouched, as we need to wakeup all the tasks, and shouldn't be playing games in the first place. This patch was seen to save on the 'msgctl10' ltp testcase ~15% in context switches (avg out of ten runs). Although these tests are really about functionality (as opposed to performance), is does show the direct benefits of the optimization. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1469748819-19484-6-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:55:02 +00:00
if (msg_fits_inqueue(msq, msgsz))
break;
/* queue full, wait: */
if (msgflg & IPC_NOWAIT) {
err = -EAGAIN;
goto out_unlock0;
}
/* enqueue the sender and prepare to block */
ipc/msg: avoid waking sender upon full queue Blocked tasks queued in q_senders waiting for their message to fit in the queue are blindly awoken every time we think there's a remote chance this might happen. This could cause numerous (and expensive -- thundering herd-ish) bogus wakeups if the queue is still really full. Adding to the scheduling cost/overhead, there's also the fact that we need to take the ipc object lock and requeue ourselves in the q_senders list. By keeping track of the blocked sender's message size, we can know previously if the wakeup ought to occur or not. Otherwise, to maintain the current wakeup order we just move it to the tail. This is exactly what occurs right now if the sender needs to go back to sleep. The case of EIDRM is left completely untouched, as we need to wakeup all the tasks, and shouldn't be playing games in the first place. This patch was seen to save on the 'msgctl10' ltp testcase ~15% in context switches (avg out of ten runs). Although these tests are really about functionality (as opposed to performance), is does show the direct benefits of the optimization. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1469748819-19484-6-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:55:02 +00:00
ss_add(msq, &s, msgsz);
ipc,sem: fine grained locking for semtimedop Introduce finer grained locking for semtimedop, to handle the common case of a program wanting to manipulate one semaphore from an array with multiple semaphores. If the call is a semop manipulating just one semaphore in an array with multiple semaphores, only take the lock for that semaphore itself. If the call needs to manipulate multiple semaphores, or another caller is in a transaction that manipulates multiple semaphores, the sem_array lock is taken, as well as all the locks for the individual semaphores. On a 24 CPU system, performance numbers with the semop-multi test with N threads and N semaphores, look like this: vanilla Davidlohr's Davidlohr's + Davidlohr's + threads patches rwlock patches v3 patches 10 610652 726325 1783589 2142206 20 341570 365699 1520453 1977878 30 288102 307037 1498167 2037995 40 290714 305955 1612665 2256484 50 288620 312890 1733453 2650292 60 289987 306043 1649360 2388008 70 291298 306347 1723167 2717486 80 290948 305662 1729545 2763582 90 290996 306680 1736021 2757524 100 292243 306700 1773700 3059159 [davidlohr.bueso@hp.com: do not call sem_lock when bogus sma] [davidlohr.bueso@hp.com: make refcounter atomic] Signed-off-by: Rik van Riel <riel@redhat.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: Chegu Vinod <chegu_vinod@hp.com> Cc: Jason Low <jason.low2@hp.com> Reviewed-by: Michel Lespinasse <walken@google.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Stanislav Kinsbursky <skinsbursky@parallels.com> Tested-by: Emmanuel Benisty <benisty.e@gmail.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-05-01 02:15:44 +00:00
if (!ipc_rcu_getref(&msq->q_perm)) {
ipc,sem: fine grained locking for semtimedop Introduce finer grained locking for semtimedop, to handle the common case of a program wanting to manipulate one semaphore from an array with multiple semaphores. If the call is a semop manipulating just one semaphore in an array with multiple semaphores, only take the lock for that semaphore itself. If the call needs to manipulate multiple semaphores, or another caller is in a transaction that manipulates multiple semaphores, the sem_array lock is taken, as well as all the locks for the individual semaphores. On a 24 CPU system, performance numbers with the semop-multi test with N threads and N semaphores, look like this: vanilla Davidlohr's Davidlohr's + Davidlohr's + threads patches rwlock patches v3 patches 10 610652 726325 1783589 2142206 20 341570 365699 1520453 1977878 30 288102 307037 1498167 2037995 40 290714 305955 1612665 2256484 50 288620 312890 1733453 2650292 60 289987 306043 1649360 2388008 70 291298 306347 1723167 2717486 80 290948 305662 1729545 2763582 90 290996 306680 1736021 2757524 100 292243 306700 1773700 3059159 [davidlohr.bueso@hp.com: do not call sem_lock when bogus sma] [davidlohr.bueso@hp.com: make refcounter atomic] Signed-off-by: Rik van Riel <riel@redhat.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: Chegu Vinod <chegu_vinod@hp.com> Cc: Jason Low <jason.low2@hp.com> Reviewed-by: Michel Lespinasse <walken@google.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Stanislav Kinsbursky <skinsbursky@parallels.com> Tested-by: Emmanuel Benisty <benisty.e@gmail.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-05-01 02:15:44 +00:00
err = -EIDRM;
goto out_unlock0;
ipc,sem: fine grained locking for semtimedop Introduce finer grained locking for semtimedop, to handle the common case of a program wanting to manipulate one semaphore from an array with multiple semaphores. If the call is a semop manipulating just one semaphore in an array with multiple semaphores, only take the lock for that semaphore itself. If the call needs to manipulate multiple semaphores, or another caller is in a transaction that manipulates multiple semaphores, the sem_array lock is taken, as well as all the locks for the individual semaphores. On a 24 CPU system, performance numbers with the semop-multi test with N threads and N semaphores, look like this: vanilla Davidlohr's Davidlohr's + Davidlohr's + threads patches rwlock patches v3 patches 10 610652 726325 1783589 2142206 20 341570 365699 1520453 1977878 30 288102 307037 1498167 2037995 40 290714 305955 1612665 2256484 50 288620 312890 1733453 2650292 60 289987 306043 1649360 2388008 70 291298 306347 1723167 2717486 80 290948 305662 1729545 2763582 90 290996 306680 1736021 2757524 100 292243 306700 1773700 3059159 [davidlohr.bueso@hp.com: do not call sem_lock when bogus sma] [davidlohr.bueso@hp.com: make refcounter atomic] Signed-off-by: Rik van Riel <riel@redhat.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: Chegu Vinod <chegu_vinod@hp.com> Cc: Jason Low <jason.low2@hp.com> Reviewed-by: Michel Lespinasse <walken@google.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Stanislav Kinsbursky <skinsbursky@parallels.com> Tested-by: Emmanuel Benisty <benisty.e@gmail.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-05-01 02:15:44 +00:00
}
ipc_unlock_object(&msq->q_perm);
rcu_read_unlock();
schedule();
rcu_read_lock();
ipc_lock_object(&msq->q_perm);
ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
/* raced with RMID? */
if (!ipc_valid_object(&msq->q_perm)) {
err = -EIDRM;
goto out_unlock0;
}
ss_del(&s);
if (signal_pending(current)) {
err = -ERESTARTNOHAND;
goto out_unlock0;
}
}
ipc/msg: avoid waking sender upon full queue Blocked tasks queued in q_senders waiting for their message to fit in the queue are blindly awoken every time we think there's a remote chance this might happen. This could cause numerous (and expensive -- thundering herd-ish) bogus wakeups if the queue is still really full. Adding to the scheduling cost/overhead, there's also the fact that we need to take the ipc object lock and requeue ourselves in the q_senders list. By keeping track of the blocked sender's message size, we can know previously if the wakeup ought to occur or not. Otherwise, to maintain the current wakeup order we just move it to the tail. This is exactly what occurs right now if the sender needs to go back to sleep. The case of EIDRM is left completely untouched, as we need to wakeup all the tasks, and shouldn't be playing games in the first place. This patch was seen to save on the 'msgctl10' ltp testcase ~15% in context switches (avg out of ten runs). Although these tests are really about functionality (as opposed to performance), is does show the direct benefits of the optimization. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1469748819-19484-6-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:55:02 +00:00
ipc/msg: Fix msgctl(..., IPC_STAT, ...) between pid namespaces Today msg_lspid and msg_lrpid are remembered in the pid namespace of the creator and the processes that last send or received a sysvipc message. If you have processes in multiple pid namespaces that is just wrong. The process ids reported will not make the least bit of sense. This fix is slightly more susceptible to a performance problem than the related fix for System V shared memory. By definition the pids are updated by msgsnd and msgrcv, the fast path of System V message queues. The only concern over the previous implementation is the incrementing and decrementing of the pid reference count. As that is the only difference and multiple updates by of the task_tgid by threads in the same process have been shown in af_unix sockets to create a cache line ping-pong between cpus of the same processor. In this case I don't expect cache lines holding pid reference counts to ping pong between cpus. As senders and receivers update different pids there is a natural separation there. Further if multiple threads of the same process either send or receive messages the pid will be updated to the same value and ipc_update_pid will avoid the reference count update. Which means in the common case I expect msg_lspid and msg_lrpid to remain constant, and reference counts not to be updated when messages are sent. In rare cases it may be possible to trigger the issue which was observed for af_unix sockets, but it will require multiple processes with multiple threads to be either sending or receiving messages. It just does not feel likely that anyone would do that in practice. This change updates msgctl(..., IPC_STAT, ...) to return msg_lspid and msg_lrpid in the pid namespace of the process calling stat. This change also updates cat /proc/sysvipc/msg to return print msg_lspid and msg_lrpid in the pid namespace of the process that opened the proc file. Fixes: b488893a390e ("pid namespaces: changes to show virtual ids to user") Reviewed-by: Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-03-23 05:42:21 +00:00
ipc_update_pid(&msq->q_lspid, task_tgid(current));
msq->q_stime = get_seconds();
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
if (!pipelined_send(msq, msg, &wake_q)) {
/* no one is waiting for this message, enqueue it */
list_add_tail(&msg->m_list, &msq->q_messages);
msq->q_cbytes += msgsz;
msq->q_qnum++;
atomic_add(msgsz, &ns->msg_bytes);
atomic_inc(&ns->msg_hdrs);
}
err = 0;
msg = NULL;
out_unlock0:
ipc_unlock_object(&msq->q_perm);
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
wake_up_q(&wake_q);
out_unlock1:
rcu_read_unlock();
if (msg != NULL)
free_msg(msg);
return err;
}
long ksys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz,
int msgflg)
{
long mtype;
if (get_user(mtype, &msgp->mtype))
return -EFAULT;
return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
}
SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
int, msgflg)
{
return ksys_msgsnd(msqid, msgp, msgsz, msgflg);
}
#ifdef CONFIG_COMPAT
struct compat_msgbuf {
compat_long_t mtype;
char mtext[1];
};
long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
compat_ssize_t msgsz, int msgflg)
{
struct compat_msgbuf __user *up = compat_ptr(msgp);
compat_long_t mtype;
if (get_user(mtype, &up->mtype))
return -EFAULT;
return do_msgsnd(msqid, mtype, up->mtext, (ssize_t)msgsz, msgflg);
}
COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp,
compat_ssize_t, msgsz, int, msgflg)
{
return compat_ksys_msgsnd(msqid, msgp, msgsz, msgflg);
}
#endif
static inline int convert_mode(long *msgtyp, int msgflg)
{
if (msgflg & MSG_COPY)
return SEARCH_NUMBER;
/*
* find message of correct type.
* msgtyp = 0 => get first.
* msgtyp > 0 => get first message of matching type.
* msgtyp < 0 => get message with least type must be < abs(msgtype).
*/
if (*msgtyp == 0)
return SEARCH_ANY;
if (*msgtyp < 0) {
if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */
*msgtyp = LONG_MAX;
else
*msgtyp = -*msgtyp;
return SEARCH_LESSEQUAL;
}
if (msgflg & MSG_EXCEPT)
return SEARCH_NOTEQUAL;
return SEARCH_EQUAL;
}
static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
{
struct msgbuf __user *msgp = dest;
size_t msgsz;
if (put_user(msg->m_type, &msgp->mtype))
return -EFAULT;
msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
if (store_msg(msgp->mtext, msg, msgsz))
return -EFAULT;
return msgsz;
}
#ifdef CONFIG_CHECKPOINT_RESTORE
/*
* This function creates new kernel message structure, large enough to store
* bufsz message bytes.
*/
static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
{
struct msg_msg *copy;
/*
* Create dummy message to copy real message to.
*/
copy = load_msg(buf, bufsz);
if (!IS_ERR(copy))
copy->m_ts = bufsz;
return copy;
}
static inline void free_copy(struct msg_msg *copy)
{
if (copy)
free_msg(copy);
}
#else
static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
{
return ERR_PTR(-ENOSYS);
}
static inline void free_copy(struct msg_msg *copy)
{
}
#endif
static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
{
struct msg_msg *msg, *found = NULL;
long count = 0;
list_for_each_entry(msg, &msq->q_messages, m_list) {
if (testmsg(msg, *msgtyp, mode) &&
!security_msg_queue_msgrcv(&msq->q_perm, msg, current,
*msgtyp, mode)) {
if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
*msgtyp = msg->m_type - 1;
found = msg;
} else if (mode == SEARCH_NUMBER) {
if (*msgtyp == count)
return msg;
} else
return msg;
count++;
}
}
return found ?: ERR_PTR(-EAGAIN);
}
static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
long (*msg_handler)(void __user *, struct msg_msg *, size_t))
{
int mode;
struct msg_queue *msq;
struct ipc_namespace *ns;
struct msg_msg *msg, *copy = NULL;
DEFINE_WAKE_Q(wake_q);
ns = current->nsproxy->ipc_ns;
if (msqid < 0 || (long) bufsz < 0)
return -EINVAL;
if (msgflg & MSG_COPY) {
ipc: Fix 2 bugs in msgrcv() MSG_COPY implementation While testing and documenting the msgrcv() MSG_COPY flag that Stanislav Kinsbursky added in commit 4a674f34ba04 ("ipc: introduce message queue copy feature" => kernel 3.8), I discovered a couple of bugs in the implementation. The two bugs concern MSG_COPY interactions with other msgrcv() flags, namely: (A) MSG_COPY + MSG_EXCEPT (B) MSG_COPY + !IPC_NOWAIT The bugs are distinct (and the fix for the first one is obvious), however my fix for both is a single-line patch, which is why I'm combining them in a single mail, rather than writing two mails+patches. ===== (A) MSG_COPY + MSG_EXCEPT ===== With the addition of the MSG_COPY flag, there are now two msgrcv() flags--MSG_COPY and MSG_EXCEPT--that modify the meaning of the 'msgtyp' argument in unrelated ways. Specifying both in the same call is a logical error that is currently permitted, with the effect that MSG_COPY has priority and MSG_EXCEPT is ignored. The call should give an error if both flags are specified. The patch below implements that behavior. ===== (B) (B) MSG_COPY + !IPC_NOWAIT ===== The test code that was submitted in commit 3a665531a3b7 ("selftests: IPC message queue copy feature test") shows MSG_COPY being used in conjunction with IPC_NOWAIT. In other words, if there is no message at the position 'msgtyp'. return immediately with the error in ENOMSG. What was not (fully) tested is the behavior if MSG_COPY is specified *without* IPC_NOWAIT, and there is an odd behavior. If the queue contains less than 'msgtyp' messages, then the call blocks until the next message is written to the queue. At that point, the msgrcv() call returns a copy of the newly added message, regardless of whether that message is at the ordinal position 'msgtyp'. This is clearly bogus, and problematic for applications that might want to make use of the MSG_COPY flag. I considered the following possible solutions to this problem: (1) Force the call to block until a message *does* appear at the position 'msgtyp'. (2) If the MSG_COPY flag is specified, the kernel should implicitly add IPC_NOWAIT, so that the call fails with ENOMSG for this case. (3) If the MSG_COPY flag is specified, but IPC_NOWAIT is not, generate an error (probably, EINVAL is the right one). I do not know if any application would really want to have the functionality of solution (1), especially since an application can determine in advance the number of messages in the queue using msgctl() IPC_STAT. Obviously, this solution would be the most work to implement. Solution (2) would have the effect of silently fixing any applications that tried to employ broken behavior. However, it would mean that if we later decided to implement solution (1), then user-space could not easily detect what the kernel supports (but, since I'm somewhat doubtful that solution (1) is needed, I'm not sure that this is much of a problem). Solution (3) would have the effect of informing broken applications that they are doing something broken. The downside is that this would cause a ABI breakage for any applications that are currently employing the broken behavior. However: a) Those applications are almost certainly not getting the results they expect. b) Possibly, those applications don't even exist, because MSG_COPY is currently hidden behind CONFIG_CHECKPOINT_RESTORE. The upside of solution (3) is that if we later decided to implement solution (1), user-space could determine what the kernel supports, via the error return. In my view, solution (3) is mildly preferable to solution (2), and solution (1) could still be done later if anyone really cares. The patch below implements solution (3). PS. For anyone out there still listening, it's the usual story: documenting an API (and the thinking about, and the testing of the API, that documentation entails) is the one of the single best ways of finding bugs in the API, as I've learned from a lot of experience. Best to do that documentation before releasing the API. Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com> Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: stable@vger.kernel.org Cc: Serge Hallyn <serge.hallyn@canonical.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-03-10 13:46:07 +00:00
if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
return -EINVAL;
copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
if (IS_ERR(copy))
return PTR_ERR(copy);
}
mode = convert_mode(&msgtyp, msgflg);
rcu_read_lock();
msq = msq_obtain_object_check(ns, msqid);
if (IS_ERR(msq)) {
rcu_read_unlock();
free_copy(copy);
return PTR_ERR(msq);
}
for (;;) {
struct msg_receiver msr_d;
msg = ERR_PTR(-EACCES);
if (ipcperms(ns, &msq->q_perm, S_IRUGO))
goto out_unlock1;
ipc_lock_object(&msq->q_perm);
/* raced with RMID? */
if (!ipc_valid_object(&msq->q_perm)) {
msg = ERR_PTR(-EIDRM);
goto out_unlock0;
}
msg = find_msg(msq, &msgtyp, mode);
if (!IS_ERR(msg)) {
/*
* Found a suitable message.
* Unlink it from the queue.
*/
if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
msg = ERR_PTR(-E2BIG);
goto out_unlock0;
}
/*
* If we are copying, then do not unlink message and do
* not update queue parameters.
*/
if (msgflg & MSG_COPY) {
msg = copy_msg(msg, copy);
goto out_unlock0;
}
list_del(&msg->m_list);
msq->q_qnum--;
msq->q_rtime = get_seconds();
ipc/msg: Fix msgctl(..., IPC_STAT, ...) between pid namespaces Today msg_lspid and msg_lrpid are remembered in the pid namespace of the creator and the processes that last send or received a sysvipc message. If you have processes in multiple pid namespaces that is just wrong. The process ids reported will not make the least bit of sense. This fix is slightly more susceptible to a performance problem than the related fix for System V shared memory. By definition the pids are updated by msgsnd and msgrcv, the fast path of System V message queues. The only concern over the previous implementation is the incrementing and decrementing of the pid reference count. As that is the only difference and multiple updates by of the task_tgid by threads in the same process have been shown in af_unix sockets to create a cache line ping-pong between cpus of the same processor. In this case I don't expect cache lines holding pid reference counts to ping pong between cpus. As senders and receivers update different pids there is a natural separation there. Further if multiple threads of the same process either send or receive messages the pid will be updated to the same value and ipc_update_pid will avoid the reference count update. Which means in the common case I expect msg_lspid and msg_lrpid to remain constant, and reference counts not to be updated when messages are sent. In rare cases it may be possible to trigger the issue which was observed for af_unix sockets, but it will require multiple processes with multiple threads to be either sending or receiving messages. It just does not feel likely that anyone would do that in practice. This change updates msgctl(..., IPC_STAT, ...) to return msg_lspid and msg_lrpid in the pid namespace of the process calling stat. This change also updates cat /proc/sysvipc/msg to return print msg_lspid and msg_lrpid in the pid namespace of the process that opened the proc file. Fixes: b488893a390e ("pid namespaces: changes to show virtual ids to user") Reviewed-by: Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-03-23 05:42:21 +00:00
ipc_update_pid(&msq->q_lrpid, task_tgid(current));
msq->q_cbytes -= msg->m_ts;
atomic_sub(msg->m_ts, &ns->msg_bytes);
atomic_dec(&ns->msg_hdrs);
ipc/msg: avoid waking sender upon full queue Blocked tasks queued in q_senders waiting for their message to fit in the queue are blindly awoken every time we think there's a remote chance this might happen. This could cause numerous (and expensive -- thundering herd-ish) bogus wakeups if the queue is still really full. Adding to the scheduling cost/overhead, there's also the fact that we need to take the ipc object lock and requeue ourselves in the q_senders list. By keeping track of the blocked sender's message size, we can know previously if the wakeup ought to occur or not. Otherwise, to maintain the current wakeup order we just move it to the tail. This is exactly what occurs right now if the sender needs to go back to sleep. The case of EIDRM is left completely untouched, as we need to wakeup all the tasks, and shouldn't be playing games in the first place. This patch was seen to save on the 'msgctl10' ltp testcase ~15% in context switches (avg out of ten runs). Although these tests are really about functionality (as opposed to performance), is does show the direct benefits of the optimization. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1469748819-19484-6-git-send-email-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:55:02 +00:00
ss_wakeup(msq, &wake_q, false);
goto out_unlock0;
}
/* No message waiting. Wait for a message */
if (msgflg & IPC_NOWAIT) {
msg = ERR_PTR(-ENOMSG);
goto out_unlock0;
}
list_add_tail(&msr_d.r_list, &msq->q_receivers);
msr_d.r_tsk = current;
msr_d.r_msgtype = msgtyp;
msr_d.r_mode = mode;
if (msgflg & MSG_NOERROR)
msr_d.r_maxsize = INT_MAX;
else
msr_d.r_maxsize = bufsz;
msr_d.r_msg = ERR_PTR(-EAGAIN);
__set_current_state(TASK_INTERRUPTIBLE);
ipc_unlock_object(&msq->q_perm);
rcu_read_unlock();
schedule();
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
/*
* Lockless receive, part 1:
* We don't hold a reference to the queue and getting a
* reference would defeat the idea of a lockless operation,
* thus the code relies on rcu to guarantee the existence of
* msq:
* Prior to destruction, expunge_all(-EIRDM) changes r_msg.
* Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
*/
rcu_read_lock();
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
/*
* Lockless receive, part 2:
* The work in pipelined_send() and expunge_all():
* - Set pointer to message
* - Queue the receiver task for later wakeup
* - Wake up the process after the lock is dropped.
*
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
* Should the process wake up before this wakeup (due to a
* signal) it will either see the message and continue ...
*/
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
msg = READ_ONCE(msr_d.r_msg);
if (msg != ERR_PTR(-EAGAIN))
goto out_unlock1;
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
/*
* ... or see -EAGAIN, acquire the lock to check the message
* again.
*/
ipc_lock_object(&msq->q_perm);
ipc/msg: implement lockless pipelined wakeups This patch moves the wakeup_process() invocation so it is not done under the ipc global lock by making use of a lockless wake_q. With this change, the waiter is woken up once the message has been assigned and it does not need to loop on SMP if the message points to NULL. In the signal case we still need to check the pointer under the lock to verify the state. This change should also avoid the introduction of preempt_disable() in -RT which avoids a busy-loop which pools for the NULL -> !NULL change if the waiter has a higher priority compared to the waker. By making use of wake_qs, the logic of sysv msg queues is greatly simplified (and very well suited as we can batch lockless wakeups), particularly around the lockless receive algorithm. This has been tested with Manred's pmsg-shared tool on a "AMD A10-7800 Radeon R7, 12 Compute Cores 4C+8G": test | before | after | diff -----------------|------------|------------|---------- pmsg-shared 8 60 | 19,347,422 | 30,442,191 | + ~57.34 % pmsg-shared 4 60 | 21,367,197 | 35,743,458 | + ~67.28 % pmsg-shared 2 60 | 22,884,224 | 24,278,200 | + ~6.09 % Link: http://lkml.kernel.org/r/1469748819-19484-2-git-send-email-dave@stgolabs.net Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 20:54:53 +00:00
msg = msr_d.r_msg;
if (msg != ERR_PTR(-EAGAIN))
goto out_unlock0;
list_del(&msr_d.r_list);
if (signal_pending(current)) {
msg = ERR_PTR(-ERESTARTNOHAND);
goto out_unlock0;
}
ipc_unlock_object(&msq->q_perm);
}
out_unlock0:
ipc_unlock_object(&msq->q_perm);
wake_up_q(&wake_q);
out_unlock1:
rcu_read_unlock();
if (IS_ERR(msg)) {
free_copy(copy);
return PTR_ERR(msg);
}
bufsz = msg_handler(buf, msg, bufsz);
free_msg(msg);
return bufsz;
}
long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,
long msgtyp, int msgflg)
{
return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
}
SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
long, msgtyp, int, msgflg)
{
return ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
}
#ifdef CONFIG_COMPAT
static long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
{
struct compat_msgbuf __user *msgp = dest;
size_t msgsz;
if (put_user(msg->m_type, &msgp->mtype))
return -EFAULT;
msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
if (store_msg(msgp->mtext, msg, msgsz))
return -EFAULT;
return msgsz;
}
long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
compat_long_t msgtyp, int msgflg)
{
return do_msgrcv(msqid, compat_ptr(msgp), (ssize_t)msgsz, (long)msgtyp,
msgflg, compat_do_msg_fill);
}
COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp,
compat_ssize_t, msgsz, compat_long_t, msgtyp,
int, msgflg)
{
return compat_ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
}
#endif
ipc: optimize semget/shmget/msgget for lots of keys ipc_findkey() used to scan all objects to look for the wanted key. This is slow when using a high number of keys. This change adds an rhashtable of kern_ipc_perm objects in ipc_ids, so that one lookup cease to be O(n). This change gives a 865% improvement of benchmark reaim.jobs_per_min on a 56 threads Intel(R) Xeon(R) CPU E5-2695 v3 @ 2.30GHz with 256G memory [1] Other (more micro) benchmark results, by the author: On an i5 laptop, the following loop executed right after a reboot took, without and with this change: for (int i = 0, k=0x424242; i < KEYS; ++i) semget(k++, 1, IPC_CREAT | 0600); total total max single max single KEYS without with call without call with 1 3.5 4.9 µs 3.5 4.9 10 7.6 8.6 µs 3.7 4.7 32 16.2 15.9 µs 4.3 5.3 100 72.9 41.8 µs 3.7 4.7 1000 5,630.0 502.0 µs * * 10000 1,340,000.0 7,240.0 µs * * 31900 17,600,000.0 22,200.0 µs * * *: unreliable measure: high variance The duration for a lookup-only usage was obtained by the same loop once the keys are present: total total max single max single KEYS without with call without call with 1 2.1 2.5 µs 2.1 2.5 10 4.5 4.8 µs 2.2 2.3 32 13.0 10.8 µs 2.3 2.8 100 82.9 25.1 µs * 2.3 1000 5,780.0 217.0 µs * * 10000 1,470,000.0 2,520.0 µs * * 31900 17,400,000.0 7,810.0 µs * * Finally, executing each semget() in a new process gave, when still summing only the durations of these syscalls: creation: total total KEYS without with 1 3.7 5.0 µs 10 32.9 36.7 µs 32 125.0 109.0 µs 100 523.0 353.0 µs 1000 20,300.0 3,280.0 µs 10000 2,470,000.0 46,700.0 µs 31900 27,800,000.0 219,000.0 µs lookup-only: total total KEYS without with 1 2.5 2.7 µs 10 25.4 24.4 µs 32 106.0 72.6 µs 100 591.0 352.0 µs 1000 22,400.0 2,250.0 µs 10000 2,510,000.0 25,700.0 µs 31900 28,200,000.0 115,000.0 µs [1] http://lkml.kernel.org/r/20170814060507.GE23258@yexl-desktop Link: http://lkml.kernel.org/r/20170815194954.ck32ta2z35yuzpwp@debix Signed-off-by: Guillaume Knispel <guillaume.knispel@supersonicimagine.com> Reviewed-by: Marc Pardo <marc.pardo@supersonicimagine.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Kees Cook <keescook@chromium.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Serge Hallyn <serge@hallyn.com> Cc: Andrey Vagin <avagin@openvz.org> Cc: Guillaume Knispel <guillaume.knispel@supersonicimagine.com> Cc: Marc Pardo <marc.pardo@supersonicimagine.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-08 23:17:55 +00:00
int msg_init_ns(struct ipc_namespace *ns)
{
ns->msg_ctlmax = MSGMAX;
ns->msg_ctlmnb = MSGMNB;
ns->msg_ctlmni = MSGMNI;
atomic_set(&ns->msg_bytes, 0);
atomic_set(&ns->msg_hdrs, 0);
ipc: optimize semget/shmget/msgget for lots of keys ipc_findkey() used to scan all objects to look for the wanted key. This is slow when using a high number of keys. This change adds an rhashtable of kern_ipc_perm objects in ipc_ids, so that one lookup cease to be O(n). This change gives a 865% improvement of benchmark reaim.jobs_per_min on a 56 threads Intel(R) Xeon(R) CPU E5-2695 v3 @ 2.30GHz with 256G memory [1] Other (more micro) benchmark results, by the author: On an i5 laptop, the following loop executed right after a reboot took, without and with this change: for (int i = 0, k=0x424242; i < KEYS; ++i) semget(k++, 1, IPC_CREAT | 0600); total total max single max single KEYS without with call without call with 1 3.5 4.9 µs 3.5 4.9 10 7.6 8.6 µs 3.7 4.7 32 16.2 15.9 µs 4.3 5.3 100 72.9 41.8 µs 3.7 4.7 1000 5,630.0 502.0 µs * * 10000 1,340,000.0 7,240.0 µs * * 31900 17,600,000.0 22,200.0 µs * * *: unreliable measure: high variance The duration for a lookup-only usage was obtained by the same loop once the keys are present: total total max single max single KEYS without with call without call with 1 2.1 2.5 µs 2.1 2.5 10 4.5 4.8 µs 2.2 2.3 32 13.0 10.8 µs 2.3 2.8 100 82.9 25.1 µs * 2.3 1000 5,780.0 217.0 µs * * 10000 1,470,000.0 2,520.0 µs * * 31900 17,400,000.0 7,810.0 µs * * Finally, executing each semget() in a new process gave, when still summing only the durations of these syscalls: creation: total total KEYS without with 1 3.7 5.0 µs 10 32.9 36.7 µs 32 125.0 109.0 µs 100 523.0 353.0 µs 1000 20,300.0 3,280.0 µs 10000 2,470,000.0 46,700.0 µs 31900 27,800,000.0 219,000.0 µs lookup-only: total total KEYS without with 1 2.5 2.7 µs 10 25.4 24.4 µs 32 106.0 72.6 µs 100 591.0 352.0 µs 1000 22,400.0 2,250.0 µs 10000 2,510,000.0 25,700.0 µs 31900 28,200,000.0 115,000.0 µs [1] http://lkml.kernel.org/r/20170814060507.GE23258@yexl-desktop Link: http://lkml.kernel.org/r/20170815194954.ck32ta2z35yuzpwp@debix Signed-off-by: Guillaume Knispel <guillaume.knispel@supersonicimagine.com> Reviewed-by: Marc Pardo <marc.pardo@supersonicimagine.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Kees Cook <keescook@chromium.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Serge Hallyn <serge@hallyn.com> Cc: Andrey Vagin <avagin@openvz.org> Cc: Guillaume Knispel <guillaume.knispel@supersonicimagine.com> Cc: Marc Pardo <marc.pardo@supersonicimagine.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-08 23:17:55 +00:00
return ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
}
#ifdef CONFIG_IPC_NS
void msg_exit_ns(struct ipc_namespace *ns)
{
free_ipcs(ns, &msg_ids(ns), freeque);
idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
ipc: optimize semget/shmget/msgget for lots of keys ipc_findkey() used to scan all objects to look for the wanted key. This is slow when using a high number of keys. This change adds an rhashtable of kern_ipc_perm objects in ipc_ids, so that one lookup cease to be O(n). This change gives a 865% improvement of benchmark reaim.jobs_per_min on a 56 threads Intel(R) Xeon(R) CPU E5-2695 v3 @ 2.30GHz with 256G memory [1] Other (more micro) benchmark results, by the author: On an i5 laptop, the following loop executed right after a reboot took, without and with this change: for (int i = 0, k=0x424242; i < KEYS; ++i) semget(k++, 1, IPC_CREAT | 0600); total total max single max single KEYS without with call without call with 1 3.5 4.9 µs 3.5 4.9 10 7.6 8.6 µs 3.7 4.7 32 16.2 15.9 µs 4.3 5.3 100 72.9 41.8 µs 3.7 4.7 1000 5,630.0 502.0 µs * * 10000 1,340,000.0 7,240.0 µs * * 31900 17,600,000.0 22,200.0 µs * * *: unreliable measure: high variance The duration for a lookup-only usage was obtained by the same loop once the keys are present: total total max single max single KEYS without with call without call with 1 2.1 2.5 µs 2.1 2.5 10 4.5 4.8 µs 2.2 2.3 32 13.0 10.8 µs 2.3 2.8 100 82.9 25.1 µs * 2.3 1000 5,780.0 217.0 µs * * 10000 1,470,000.0 2,520.0 µs * * 31900 17,400,000.0 7,810.0 µs * * Finally, executing each semget() in a new process gave, when still summing only the durations of these syscalls: creation: total total KEYS without with 1 3.7 5.0 µs 10 32.9 36.7 µs 32 125.0 109.0 µs 100 523.0 353.0 µs 1000 20,300.0 3,280.0 µs 10000 2,470,000.0 46,700.0 µs 31900 27,800,000.0 219,000.0 µs lookup-only: total total KEYS without with 1 2.5 2.7 µs 10 25.4 24.4 µs 32 106.0 72.6 µs 100 591.0 352.0 µs 1000 22,400.0 2,250.0 µs 10000 2,510,000.0 25,700.0 µs 31900 28,200,000.0 115,000.0 µs [1] http://lkml.kernel.org/r/20170814060507.GE23258@yexl-desktop Link: http://lkml.kernel.org/r/20170815194954.ck32ta2z35yuzpwp@debix Signed-off-by: Guillaume Knispel <guillaume.knispel@supersonicimagine.com> Reviewed-by: Marc Pardo <marc.pardo@supersonicimagine.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Kees Cook <keescook@chromium.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Serge Hallyn <serge@hallyn.com> Cc: Andrey Vagin <avagin@openvz.org> Cc: Guillaume Knispel <guillaume.knispel@supersonicimagine.com> Cc: Marc Pardo <marc.pardo@supersonicimagine.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-08 23:17:55 +00:00
rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht);
}
#endif
#ifdef CONFIG_PROC_FS
static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
{
ipc/msg: Fix msgctl(..., IPC_STAT, ...) between pid namespaces Today msg_lspid and msg_lrpid are remembered in the pid namespace of the creator and the processes that last send or received a sysvipc message. If you have processes in multiple pid namespaces that is just wrong. The process ids reported will not make the least bit of sense. This fix is slightly more susceptible to a performance problem than the related fix for System V shared memory. By definition the pids are updated by msgsnd and msgrcv, the fast path of System V message queues. The only concern over the previous implementation is the incrementing and decrementing of the pid reference count. As that is the only difference and multiple updates by of the task_tgid by threads in the same process have been shown in af_unix sockets to create a cache line ping-pong between cpus of the same processor. In this case I don't expect cache lines holding pid reference counts to ping pong between cpus. As senders and receivers update different pids there is a natural separation there. Further if multiple threads of the same process either send or receive messages the pid will be updated to the same value and ipc_update_pid will avoid the reference count update. Which means in the common case I expect msg_lspid and msg_lrpid to remain constant, and reference counts not to be updated when messages are sent. In rare cases it may be possible to trigger the issue which was observed for af_unix sockets, but it will require multiple processes with multiple threads to be either sending or receiving messages. It just does not feel likely that anyone would do that in practice. This change updates msgctl(..., IPC_STAT, ...) to return msg_lspid and msg_lrpid in the pid namespace of the process calling stat. This change also updates cat /proc/sysvipc/msg to return print msg_lspid and msg_lrpid in the pid namespace of the process that opened the proc file. Fixes: b488893a390e ("pid namespaces: changes to show virtual ids to user") Reviewed-by: Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-03-23 05:42:21 +00:00
struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
struct user_namespace *user_ns = seq_user_ns(s);
struct kern_ipc_perm *ipcp = it;
struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
seq_printf(s,
"%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10llu %10llu %10llu\n",
msq->q_perm.key,
msq->q_perm.id,
msq->q_perm.mode,
msq->q_cbytes,
msq->q_qnum,
ipc/msg: Fix msgctl(..., IPC_STAT, ...) between pid namespaces Today msg_lspid and msg_lrpid are remembered in the pid namespace of the creator and the processes that last send or received a sysvipc message. If you have processes in multiple pid namespaces that is just wrong. The process ids reported will not make the least bit of sense. This fix is slightly more susceptible to a performance problem than the related fix for System V shared memory. By definition the pids are updated by msgsnd and msgrcv, the fast path of System V message queues. The only concern over the previous implementation is the incrementing and decrementing of the pid reference count. As that is the only difference and multiple updates by of the task_tgid by threads in the same process have been shown in af_unix sockets to create a cache line ping-pong between cpus of the same processor. In this case I don't expect cache lines holding pid reference counts to ping pong between cpus. As senders and receivers update different pids there is a natural separation there. Further if multiple threads of the same process either send or receive messages the pid will be updated to the same value and ipc_update_pid will avoid the reference count update. Which means in the common case I expect msg_lspid and msg_lrpid to remain constant, and reference counts not to be updated when messages are sent. In rare cases it may be possible to trigger the issue which was observed for af_unix sockets, but it will require multiple processes with multiple threads to be either sending or receiving messages. It just does not feel likely that anyone would do that in practice. This change updates msgctl(..., IPC_STAT, ...) to return msg_lspid and msg_lrpid in the pid namespace of the process calling stat. This change also updates cat /proc/sysvipc/msg to return print msg_lspid and msg_lrpid in the pid namespace of the process that opened the proc file. Fixes: b488893a390e ("pid namespaces: changes to show virtual ids to user") Reviewed-by: Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-03-23 05:42:21 +00:00
pid_nr_ns(msq->q_lspid, pid_ns),
pid_nr_ns(msq->q_lrpid, pid_ns),
from_kuid_munged(user_ns, msq->q_perm.uid),
from_kgid_munged(user_ns, msq->q_perm.gid),
from_kuid_munged(user_ns, msq->q_perm.cuid),
from_kgid_munged(user_ns, msq->q_perm.cgid),
msq->q_stime,
msq->q_rtime,
msq->q_ctime);
return 0;
}
#endif
ipc: optimize semget/shmget/msgget for lots of keys ipc_findkey() used to scan all objects to look for the wanted key. This is slow when using a high number of keys. This change adds an rhashtable of kern_ipc_perm objects in ipc_ids, so that one lookup cease to be O(n). This change gives a 865% improvement of benchmark reaim.jobs_per_min on a 56 threads Intel(R) Xeon(R) CPU E5-2695 v3 @ 2.30GHz with 256G memory [1] Other (more micro) benchmark results, by the author: On an i5 laptop, the following loop executed right after a reboot took, without and with this change: for (int i = 0, k=0x424242; i < KEYS; ++i) semget(k++, 1, IPC_CREAT | 0600); total total max single max single KEYS without with call without call with 1 3.5 4.9 µs 3.5 4.9 10 7.6 8.6 µs 3.7 4.7 32 16.2 15.9 µs 4.3 5.3 100 72.9 41.8 µs 3.7 4.7 1000 5,630.0 502.0 µs * * 10000 1,340,000.0 7,240.0 µs * * 31900 17,600,000.0 22,200.0 µs * * *: unreliable measure: high variance The duration for a lookup-only usage was obtained by the same loop once the keys are present: total total max single max single KEYS without with call without call with 1 2.1 2.5 µs 2.1 2.5 10 4.5 4.8 µs 2.2 2.3 32 13.0 10.8 µs 2.3 2.8 100 82.9 25.1 µs * 2.3 1000 5,780.0 217.0 µs * * 10000 1,470,000.0 2,520.0 µs * * 31900 17,400,000.0 7,810.0 µs * * Finally, executing each semget() in a new process gave, when still summing only the durations of these syscalls: creation: total total KEYS without with 1 3.7 5.0 µs 10 32.9 36.7 µs 32 125.0 109.0 µs 100 523.0 353.0 µs 1000 20,300.0 3,280.0 µs 10000 2,470,000.0 46,700.0 µs 31900 27,800,000.0 219,000.0 µs lookup-only: total total KEYS without with 1 2.5 2.7 µs 10 25.4 24.4 µs 32 106.0 72.6 µs 100 591.0 352.0 µs 1000 22,400.0 2,250.0 µs 10000 2,510,000.0 25,700.0 µs 31900 28,200,000.0 115,000.0 µs [1] http://lkml.kernel.org/r/20170814060507.GE23258@yexl-desktop Link: http://lkml.kernel.org/r/20170815194954.ck32ta2z35yuzpwp@debix Signed-off-by: Guillaume Knispel <guillaume.knispel@supersonicimagine.com> Reviewed-by: Marc Pardo <marc.pardo@supersonicimagine.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Kees Cook <keescook@chromium.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Serge Hallyn <serge@hallyn.com> Cc: Andrey Vagin <avagin@openvz.org> Cc: Guillaume Knispel <guillaume.knispel@supersonicimagine.com> Cc: Marc Pardo <marc.pardo@supersonicimagine.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-08 23:17:55 +00:00
int __init msg_init(void)
{
ipc: optimize semget/shmget/msgget for lots of keys ipc_findkey() used to scan all objects to look for the wanted key. This is slow when using a high number of keys. This change adds an rhashtable of kern_ipc_perm objects in ipc_ids, so that one lookup cease to be O(n). This change gives a 865% improvement of benchmark reaim.jobs_per_min on a 56 threads Intel(R) Xeon(R) CPU E5-2695 v3 @ 2.30GHz with 256G memory [1] Other (more micro) benchmark results, by the author: On an i5 laptop, the following loop executed right after a reboot took, without and with this change: for (int i = 0, k=0x424242; i < KEYS; ++i) semget(k++, 1, IPC_CREAT | 0600); total total max single max single KEYS without with call without call with 1 3.5 4.9 µs 3.5 4.9 10 7.6 8.6 µs 3.7 4.7 32 16.2 15.9 µs 4.3 5.3 100 72.9 41.8 µs 3.7 4.7 1000 5,630.0 502.0 µs * * 10000 1,340,000.0 7,240.0 µs * * 31900 17,600,000.0 22,200.0 µs * * *: unreliable measure: high variance The duration for a lookup-only usage was obtained by the same loop once the keys are present: total total max single max single KEYS without with call without call with 1 2.1 2.5 µs 2.1 2.5 10 4.5 4.8 µs 2.2 2.3 32 13.0 10.8 µs 2.3 2.8 100 82.9 25.1 µs * 2.3 1000 5,780.0 217.0 µs * * 10000 1,470,000.0 2,520.0 µs * * 31900 17,400,000.0 7,810.0 µs * * Finally, executing each semget() in a new process gave, when still summing only the durations of these syscalls: creation: total total KEYS without with 1 3.7 5.0 µs 10 32.9 36.7 µs 32 125.0 109.0 µs 100 523.0 353.0 µs 1000 20,300.0 3,280.0 µs 10000 2,470,000.0 46,700.0 µs 31900 27,800,000.0 219,000.0 µs lookup-only: total total KEYS without with 1 2.5 2.7 µs 10 25.4 24.4 µs 32 106.0 72.6 µs 100 591.0 352.0 µs 1000 22,400.0 2,250.0 µs 10000 2,510,000.0 25,700.0 µs 31900 28,200,000.0 115,000.0 µs [1] http://lkml.kernel.org/r/20170814060507.GE23258@yexl-desktop Link: http://lkml.kernel.org/r/20170815194954.ck32ta2z35yuzpwp@debix Signed-off-by: Guillaume Knispel <guillaume.knispel@supersonicimagine.com> Reviewed-by: Marc Pardo <marc.pardo@supersonicimagine.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Kees Cook <keescook@chromium.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Serge Hallyn <serge@hallyn.com> Cc: Andrey Vagin <avagin@openvz.org> Cc: Guillaume Knispel <guillaume.knispel@supersonicimagine.com> Cc: Marc Pardo <marc.pardo@supersonicimagine.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-08 23:17:55 +00:00
const int err = msg_init_ns(&init_ipc_ns);
ipc_init_proc_interface("sysvipc/msg",
" key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n",
IPC_MSG_IDS, sysvipc_msg_proc_show);
ipc: optimize semget/shmget/msgget for lots of keys ipc_findkey() used to scan all objects to look for the wanted key. This is slow when using a high number of keys. This change adds an rhashtable of kern_ipc_perm objects in ipc_ids, so that one lookup cease to be O(n). This change gives a 865% improvement of benchmark reaim.jobs_per_min on a 56 threads Intel(R) Xeon(R) CPU E5-2695 v3 @ 2.30GHz with 256G memory [1] Other (more micro) benchmark results, by the author: On an i5 laptop, the following loop executed right after a reboot took, without and with this change: for (int i = 0, k=0x424242; i < KEYS; ++i) semget(k++, 1, IPC_CREAT | 0600); total total max single max single KEYS without with call without call with 1 3.5 4.9 µs 3.5 4.9 10 7.6 8.6 µs 3.7 4.7 32 16.2 15.9 µs 4.3 5.3 100 72.9 41.8 µs 3.7 4.7 1000 5,630.0 502.0 µs * * 10000 1,340,000.0 7,240.0 µs * * 31900 17,600,000.0 22,200.0 µs * * *: unreliable measure: high variance The duration for a lookup-only usage was obtained by the same loop once the keys are present: total total max single max single KEYS without with call without call with 1 2.1 2.5 µs 2.1 2.5 10 4.5 4.8 µs 2.2 2.3 32 13.0 10.8 µs 2.3 2.8 100 82.9 25.1 µs * 2.3 1000 5,780.0 217.0 µs * * 10000 1,470,000.0 2,520.0 µs * * 31900 17,400,000.0 7,810.0 µs * * Finally, executing each semget() in a new process gave, when still summing only the durations of these syscalls: creation: total total KEYS without with 1 3.7 5.0 µs 10 32.9 36.7 µs 32 125.0 109.0 µs 100 523.0 353.0 µs 1000 20,300.0 3,280.0 µs 10000 2,470,000.0 46,700.0 µs 31900 27,800,000.0 219,000.0 µs lookup-only: total total KEYS without with 1 2.5 2.7 µs 10 25.4 24.4 µs 32 106.0 72.6 µs 100 591.0 352.0 µs 1000 22,400.0 2,250.0 µs 10000 2,510,000.0 25,700.0 µs 31900 28,200,000.0 115,000.0 µs [1] http://lkml.kernel.org/r/20170814060507.GE23258@yexl-desktop Link: http://lkml.kernel.org/r/20170815194954.ck32ta2z35yuzpwp@debix Signed-off-by: Guillaume Knispel <guillaume.knispel@supersonicimagine.com> Reviewed-by: Marc Pardo <marc.pardo@supersonicimagine.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Kees Cook <keescook@chromium.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Serge Hallyn <serge@hallyn.com> Cc: Andrey Vagin <avagin@openvz.org> Cc: Guillaume Knispel <guillaume.knispel@supersonicimagine.com> Cc: Marc Pardo <marc.pardo@supersonicimagine.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-08 23:17:55 +00:00
return err;
}