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Linus Torvalds 8053871d0f smp: Fix smp_call_function_single_async() locking 
The current smp_function_call code suffers a number of problems, most
notably smp_call_function_single_async() is broken.

The problem is that flush_smp_call_function_queue() does csd_unlock()
_after_ calling csd->func(). This means that a caller cannot properly
synchronize the csd usage as it has to.

Change the code to release the csd before calling ->func() for the
async case, and put a WARN_ON_ONCE(csd->flags & CSD_FLAG_LOCK) in
smp_call_function_single_async() to warn us of improper serialization,
because any waiting there can results in deadlocks when called with
IRQs disabled.

Rename the (currently) unused WAIT flag to SYNCHRONOUS and (re)use it
such that we know what to do in flush_smp_call_function_queue().

Rework csd_{,un}lock() to use smp_load_acquire() / smp_store_release()
to avoid some full barriers while more clearly providing lock
semantics.

Finally move the csd maintenance out of generic_exec_single() into its
callers for clearer code.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[ Added changelog. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Rafael David Tinoco <inaddy@ubuntu.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/CA+55aFz492bzLFhdbKN-Hygjcreup7CjMEYk3nTSfRWjppz-OA@mail.gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-17 09:57:52 +02:00
..
bpf Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-01-27 13:55:36 -08:00
configs x86: Add "make tinyconfig" to configure the tiniest possible kernel 2014-08-08 16:30:24 -07:00
debug debug: prevent entering debug mode on panic/exception. 2015-02-19 12:39:03 -06:00
events perf: Fix irq_work 'tail' recursion 2015-03-23 10:46:32 +01:00
gcov kbuild,gcov: simplify kernel/gcov/Makefile more 2015-01-09 17:25:44 +01:00
irq genirq / PM: Add flag for shared NO_SUSPEND interrupt lines 2015-03-04 21:42:19 +01:00
livepatch livepatch: Fix subtle race with coming and going modules 2015-03-17 10:31:54 +01:00
locking lockdep: Make print_lock() robust against concurrent release 2015-04-17 09:42:14 +02:00
power Revert "PM / hibernate: avoid unsafe pages in e820 reserved regions" 2015-04-07 01:13:23 +02:00
printk console: Fix console name size mismatch 2015-03-07 03:39:55 +01:00
rcu Merge branches 'core-urgent-for-linus' and 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-02-21 10:36:06 -08:00
sched Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-04-13 11:08:28 -07:00
time timers/PM: Drop unnecessary braces from tick_freeze() 2015-04-03 15:15:52 +02:00
trace ftrace: Fix ftrace enable ordering of sysctl ftrace_enabled 2015-03-09 10:55:34 -04:00
.gitignore
acct.c new fs_pin killing logics 2015-01-25 23:17:28 -05:00
async.c kernel/async.c: switch to pr_foo() 2014-10-09 22:26:04 -04:00
audit.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-12-30 10:45:47 -08:00
audit.h audit: replace getname()/putname() hacks with reference counters 2015-01-23 00:23:58 -05:00
audit_tree.c fsnotify: unify inode and mount marks handling 2014-12-13 12:42:53 -08:00
audit_watch.c audit: invalid op= values for rules 2014-09-23 16:37:53 -04:00
auditfilter.c Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit 2015-02-11 20:07:47 -08:00
auditsc.c Merge branch 'getname2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2015-02-17 15:27:47 -08:00
backtracetest.c
bounds.c page-cgroup: get rid of NR_PCG_FLAGS 2014-08-08 15:57:18 -07:00
capability.c CAPABILITIES: remove undefined caps from all processes 2014-07-24 21:53:47 +10:00
cgroup.c kernfs: remove KERNFS_STATIC_NAME 2015-02-13 21:21:36 -08:00
cgroup_freezer.c cgroup: rename cgroup_subsys->base_cftypes to ->legacy_cftypes 2014-07-15 11:05:09 -04:00
compat.c all arches, signal: move restart_block to struct task_struct 2015-02-12 18:54:12 -08:00
configs.c
context_tracking.c sched: stop the unbound recursion in preempt_schedule_context() 2014-10-28 10:46:05 +01:00
cpu.c clockevents: Cleanup dead cpu explicitely 2015-04-03 08:44:37 +02:00
cpu_pm.c
cpuset.c cpuset: Fix cpuset sched_relax_domain_level 2015-03-02 11:55:04 -05:00
crash_dump.c crash_dump: Make is_kdump_kernel() accessible from modules 2014-08-25 15:42:19 -07:00
cred.c
delayacct.c delayacct: Remove braindamaged type conversions 2014-07-23 10:18:06 -07:00
dma.c
elfcore.c
exec_domain.c
exit.c oom, PM: make OOM detection in the freezer path raceless 2015-02-11 17:06:03 -08:00
extable.c ftrace/x86/extable: Add is_ftrace_trampoline() function 2014-11-19 15:25:26 -05:00
fork.c mm: do not use mm->nr_pmds on !MMU configurations 2015-02-12 18:54:10 -08:00
freezer.c freezer: remove obsolete comments in __thaw_task() 2014-10-21 23:44:20 +02:00
futex.c Linux 34.0-rc1 2015-02-24 08:41:07 +01:00
futex_compat.c
groups.c userns: Don't allow setgroups until a gid mapping has been setablished 2014-12-09 16:58:40 -06:00
hung_task.c
irq_work.c percpu: Convert remaining __get_cpu_var uses in 3.18-rcX 2014-10-29 11:18:18 -04:00
jump_label.c
kallsyms.c kernel/kallsyms.c: use __seq_open_private() 2014-10-14 02:18:16 +02:00
kcmp.c kcmp: fix standard comparison bug 2014-09-10 15:42:12 -07:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks locking/mcs: Better differentiate between MCS variants 2015-01-14 15:07:32 +01:00
Kconfig.preempt
kexec.c kexec: simplify conditional 2015-02-17 14:34:51 -08:00
kmod.c usermodehelper: kill the kmod_thread_locker logic 2014-12-10 17:41:17 -08:00
kprobes.c kprobes: makes kprobes/enabled works correctly for optimized kprobes. 2015-02-13 21:21:42 -08:00
ksysfs.c
kthread.c kernel/kthread.c: partial revert of 81c98869fa ("kthread: ensure locality of task_struct allocations") 2014-10-09 22:25:51 -04:00
latencytop.c
Makefile Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2015-02-11 20:25:11 -08:00
module-internal.h
module.c Copy the kernel module data from user space in chunks 2015-04-08 14:35:48 -07:00
module_signing.c
notifier.c rcu: Make SRCU optional by using CONFIG_SRCU 2015-01-06 11:04:29 -08:00
nsproxy.c bury struct proc_ns in fs/proc 2014-12-04 14:34:54 -05:00
padata.c padata: use %*pb[l] to print bitmaps including cpumasks and nodemasks 2015-02-13 21:21:38 -08:00
panic.c livepatch: kernel: add TAINT_LIVEPATCH 2014-12-22 15:40:48 +01:00
params.c param: fix uninitialized read with CONFIG_DEBUG_LOCK_ALLOC 2015-01-20 11:38:31 +10:30
pid.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-12-16 15:53:03 -08:00
pid_namespace.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-12-16 15:53:03 -08:00
profile.c profile: use %*pb[l] to print bitmaps including cpumasks and nodemasks 2015-02-13 21:21:38 -08:00
ptrace.c ptrace: remove linux/compat.h inclusion under CONFIG_COMPAT 2015-02-17 14:34:51 -08:00
range.c kernel: avoid overflow in cmp_range 2015-01-17 10:02:23 +13:00
reboot.c kernel: add support for kernel restart handler call chain 2014-09-26 00:00:06 -07:00
relay.c
resource.c resources: Move struct resource_list_entry from ACPI into resource core 2015-02-05 15:09:25 +01:00
seccomp.c seccomp: cap SECCOMP_RET_ERRNO data to MAX_ERRNO 2015-02-17 14:34:55 -08:00
signal.c signal: use current->state helpers 2015-02-17 14:34:51 -08:00
smp.c smp: Fix smp_call_function_single_async() locking 2015-04-17 09:57:52 +02:00
smpboot.c smpboot: Add missing get_online_cpus() in smpboot_register_percpu_thread() 2015-01-23 11:33:51 +01:00
smpboot.h
softirq.c Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-02-09 15:24:03 -08:00
stacktrace.c stacktrace: introduce snprint_stack_trace for buffer output 2014-12-13 12:42:48 -08:00
stop_machine.c
sys.c kernel/sys.c: fix UNAME26 for 4.0 2015-02-28 09:57:51 -08:00
sys_ni.c syscalls: implement execveat() system call 2014-12-13 12:42:51 -08:00
sysctl.c fs: add dirtytime_expire_seconds sysctl 2015-03-17 12:23:32 -04:00
sysctl_binary.c kernel: add panic_on_warn 2014-12-10 17:41:10 -08:00
system_certificates.S
system_keyring.c KEYS: validate certificate trust only with builtin keys 2014-07-17 09:35:17 -04:00
task_work.c
taskstats.c netlink: make nlmsg_end() and genlmsg_end() void 2015-01-18 01:03:45 -05:00
test_kprobes.c kernel/test_kprobes.c: use current logging functions 2014-08-08 15:57:18 -07:00
torture.c torture: Address race in module cleanup 2014-09-16 13:41:06 -07:00
tracepoint.c
tsacct.c sched: Make task->start_time nanoseconds based 2014-07-23 10:18:05 -07:00
uid16.c groups: Consolidate the setgroups permission checks 2014-12-05 17:19:27 -06:00
up.c
user-return-notifier.c scheduler: Replace __get_cpu_var with this_cpu_ptr 2014-08-26 13:45:45 -04:00
user.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2014-12-17 12:31:40 -08:00
user_namespace.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2014-12-17 12:31:40 -08:00
utsname.c copy address of proc_ns_ops into ns_common 2014-12-04 14:34:47 -05:00
utsname_sysctl.c
watchdog.c kernel/sched/clock.c: add another clock for use with the soft lockup watchdog 2015-02-12 18:54:13 -08:00
workqueue.c workqueue: fix hang involving racing cancel[_delayed]_work_sync()'s for PREEMPT_NONE 2015-03-05 08:04:13 -05:00
workqueue_internal.h