linux/net/core/netprio_cgroup.c
John Fastabend 406a3c638c net: netprio_cgroup: rework update socket logic
Instead of updating the sk_cgrp_prioidx struct field on every send
this only updates the field when a task is moved via cgroup
infrastructure.

This allows sockets that may be used by a kernel worker thread
to be managed. For example in the iscsi case today a user can
put iscsid in a netprio cgroup and control traffic will be sent
with the correct sk_cgrp_prioidx value set but as soon as data
is sent the kernel worker thread isssues a send and sk_cgrp_prioidx
is updated with the kernel worker threads value which is the
default case.

It seems more correct to only update the field when the user
explicitly sets it via control group infrastructure. This allows
the users to manage sockets that may be used with other threads.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-07-22 12:44:01 -07:00

423 lines
8.9 KiB
C

/*
* net/core/netprio_cgroup.c Priority Control Group
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Authors: Neil Horman <nhorman@tuxdriver.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/cgroup.h>
#include <linux/rcupdate.h>
#include <linux/atomic.h>
#include <net/rtnetlink.h>
#include <net/pkt_cls.h>
#include <net/sock.h>
#include <net/netprio_cgroup.h>
#include <linux/fdtable.h>
#define PRIOIDX_SZ 128
static unsigned long prioidx_map[PRIOIDX_SZ];
static DEFINE_SPINLOCK(prioidx_map_lock);
static atomic_t max_prioidx = ATOMIC_INIT(0);
static inline struct cgroup_netprio_state *cgrp_netprio_state(struct cgroup *cgrp)
{
return container_of(cgroup_subsys_state(cgrp, net_prio_subsys_id),
struct cgroup_netprio_state, css);
}
static int get_prioidx(u32 *prio)
{
unsigned long flags;
u32 prioidx;
spin_lock_irqsave(&prioidx_map_lock, flags);
prioidx = find_first_zero_bit(prioidx_map, sizeof(unsigned long) * PRIOIDX_SZ);
if (prioidx == sizeof(unsigned long) * PRIOIDX_SZ) {
spin_unlock_irqrestore(&prioidx_map_lock, flags);
return -ENOSPC;
}
set_bit(prioidx, prioidx_map);
if (atomic_read(&max_prioidx) < prioidx)
atomic_set(&max_prioidx, prioidx);
spin_unlock_irqrestore(&prioidx_map_lock, flags);
*prio = prioidx;
return 0;
}
static void put_prioidx(u32 idx)
{
unsigned long flags;
spin_lock_irqsave(&prioidx_map_lock, flags);
clear_bit(idx, prioidx_map);
spin_unlock_irqrestore(&prioidx_map_lock, flags);
}
static int extend_netdev_table(struct net_device *dev, u32 new_len)
{
size_t new_size = sizeof(struct netprio_map) +
((sizeof(u32) * new_len));
struct netprio_map *new_priomap = kzalloc(new_size, GFP_KERNEL);
struct netprio_map *old_priomap;
int i;
old_priomap = rtnl_dereference(dev->priomap);
if (!new_priomap) {
pr_warn("Unable to alloc new priomap!\n");
return -ENOMEM;
}
for (i = 0;
old_priomap && (i < old_priomap->priomap_len);
i++)
new_priomap->priomap[i] = old_priomap->priomap[i];
new_priomap->priomap_len = new_len;
rcu_assign_pointer(dev->priomap, new_priomap);
if (old_priomap)
kfree_rcu(old_priomap, rcu);
return 0;
}
static int write_update_netdev_table(struct net_device *dev)
{
int ret = 0;
u32 max_len;
struct netprio_map *map;
rtnl_lock();
max_len = atomic_read(&max_prioidx) + 1;
map = rtnl_dereference(dev->priomap);
if (!map || map->priomap_len < max_len)
ret = extend_netdev_table(dev, max_len);
rtnl_unlock();
return ret;
}
static int update_netdev_tables(void)
{
int ret = 0;
struct net_device *dev;
u32 max_len;
struct netprio_map *map;
rtnl_lock();
max_len = atomic_read(&max_prioidx) + 1;
for_each_netdev(&init_net, dev) {
map = rtnl_dereference(dev->priomap);
/*
* don't allocate priomap if we didn't
* change net_prio.ifpriomap (map == NULL),
* this will speed up skb_update_prio.
*/
if (map && map->priomap_len < max_len) {
ret = extend_netdev_table(dev, max_len);
if (ret < 0)
break;
}
}
rtnl_unlock();
return ret;
}
static struct cgroup_subsys_state *cgrp_create(struct cgroup *cgrp)
{
struct cgroup_netprio_state *cs;
int ret = -EINVAL;
cs = kzalloc(sizeof(*cs), GFP_KERNEL);
if (!cs)
return ERR_PTR(-ENOMEM);
if (cgrp->parent && cgrp_netprio_state(cgrp->parent)->prioidx)
goto out;
ret = get_prioidx(&cs->prioidx);
if (ret < 0) {
pr_warn("No space in priority index array\n");
goto out;
}
ret = update_netdev_tables();
if (ret < 0) {
put_prioidx(cs->prioidx);
goto out;
}
return &cs->css;
out:
kfree(cs);
return ERR_PTR(ret);
}
static void cgrp_destroy(struct cgroup *cgrp)
{
struct cgroup_netprio_state *cs;
struct net_device *dev;
struct netprio_map *map;
cs = cgrp_netprio_state(cgrp);
rtnl_lock();
for_each_netdev(&init_net, dev) {
map = rtnl_dereference(dev->priomap);
if (map && cs->prioidx < map->priomap_len)
map->priomap[cs->prioidx] = 0;
}
rtnl_unlock();
put_prioidx(cs->prioidx);
kfree(cs);
}
static u64 read_prioidx(struct cgroup *cgrp, struct cftype *cft)
{
return (u64)cgrp_netprio_state(cgrp)->prioidx;
}
static int read_priomap(struct cgroup *cont, struct cftype *cft,
struct cgroup_map_cb *cb)
{
struct net_device *dev;
u32 prioidx = cgrp_netprio_state(cont)->prioidx;
u32 priority;
struct netprio_map *map;
rcu_read_lock();
for_each_netdev_rcu(&init_net, dev) {
map = rcu_dereference(dev->priomap);
priority = (map && prioidx < map->priomap_len) ? map->priomap[prioidx] : 0;
cb->fill(cb, dev->name, priority);
}
rcu_read_unlock();
return 0;
}
static int write_priomap(struct cgroup *cgrp, struct cftype *cft,
const char *buffer)
{
char *devname = kstrdup(buffer, GFP_KERNEL);
int ret = -EINVAL;
u32 prioidx = cgrp_netprio_state(cgrp)->prioidx;
unsigned long priority;
char *priostr;
struct net_device *dev;
struct netprio_map *map;
if (!devname)
return -ENOMEM;
/*
* Minimally sized valid priomap string
*/
if (strlen(devname) < 3)
goto out_free_devname;
priostr = strstr(devname, " ");
if (!priostr)
goto out_free_devname;
/*
*Separate the devname from the associated priority
*and advance the priostr poitner to the priority value
*/
*priostr = '\0';
priostr++;
/*
* If the priostr points to NULL, we're at the end of the passed
* in string, and its not a valid write
*/
if (*priostr == '\0')
goto out_free_devname;
ret = kstrtoul(priostr, 10, &priority);
if (ret < 0)
goto out_free_devname;
ret = -ENODEV;
dev = dev_get_by_name(&init_net, devname);
if (!dev)
goto out_free_devname;
ret = write_update_netdev_table(dev);
if (ret < 0)
goto out_put_dev;
rcu_read_lock();
map = rcu_dereference(dev->priomap);
if (map)
map->priomap[prioidx] = priority;
rcu_read_unlock();
out_put_dev:
dev_put(dev);
out_free_devname:
kfree(devname);
return ret;
}
void net_prio_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
{
struct task_struct *p;
char *tmp = kzalloc(sizeof(char) * PATH_MAX, GFP_KERNEL);
if (!tmp) {
pr_warn("Unable to attach cgrp due to alloc failure!\n");
return;
}
cgroup_taskset_for_each(p, cgrp, tset) {
unsigned int fd;
struct fdtable *fdt;
struct files_struct *files;
task_lock(p);
files = p->files;
if (!files) {
task_unlock(p);
continue;
}
rcu_read_lock();
fdt = files_fdtable(files);
for (fd = 0; fd < fdt->max_fds; fd++) {
char *path;
struct file *file;
struct socket *sock;
unsigned long s;
int rv, err = 0;
file = fcheck_files(files, fd);
if (!file)
continue;
path = d_path(&file->f_path, tmp, PAGE_SIZE);
rv = sscanf(path, "socket:[%lu]", &s);
if (rv <= 0)
continue;
sock = sock_from_file(file, &err);
if (!err)
sock_update_netprioidx(sock->sk, p);
}
rcu_read_unlock();
task_unlock(p);
}
kfree(tmp);
}
static struct cftype ss_files[] = {
{
.name = "prioidx",
.read_u64 = read_prioidx,
},
{
.name = "ifpriomap",
.read_map = read_priomap,
.write_string = write_priomap,
},
{ } /* terminate */
};
struct cgroup_subsys net_prio_subsys = {
.name = "net_prio",
.create = cgrp_create,
.destroy = cgrp_destroy,
.attach = net_prio_attach,
#ifdef CONFIG_NETPRIO_CGROUP
.subsys_id = net_prio_subsys_id,
#endif
.base_cftypes = ss_files,
.module = THIS_MODULE
};
static int netprio_device_event(struct notifier_block *unused,
unsigned long event, void *ptr)
{
struct net_device *dev = ptr;
struct netprio_map *old;
/*
* Note this is called with rtnl_lock held so we have update side
* protection on our rcu assignments
*/
switch (event) {
case NETDEV_UNREGISTER:
old = rtnl_dereference(dev->priomap);
RCU_INIT_POINTER(dev->priomap, NULL);
if (old)
kfree_rcu(old, rcu);
break;
}
return NOTIFY_DONE;
}
static struct notifier_block netprio_device_notifier = {
.notifier_call = netprio_device_event
};
static int __init init_cgroup_netprio(void)
{
int ret;
ret = cgroup_load_subsys(&net_prio_subsys);
if (ret)
goto out;
#ifndef CONFIG_NETPRIO_CGROUP
smp_wmb();
net_prio_subsys_id = net_prio_subsys.subsys_id;
#endif
register_netdevice_notifier(&netprio_device_notifier);
out:
return ret;
}
static void __exit exit_cgroup_netprio(void)
{
struct netprio_map *old;
struct net_device *dev;
unregister_netdevice_notifier(&netprio_device_notifier);
cgroup_unload_subsys(&net_prio_subsys);
#ifndef CONFIG_NETPRIO_CGROUP
net_prio_subsys_id = -1;
synchronize_rcu();
#endif
rtnl_lock();
for_each_netdev(&init_net, dev) {
old = rtnl_dereference(dev->priomap);
RCU_INIT_POINTER(dev->priomap, NULL);
if (old)
kfree_rcu(old, rcu);
}
rtnl_unlock();
}
module_init(init_cgroup_netprio);
module_exit(exit_cgroup_netprio);
MODULE_LICENSE("GPL v2");