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net sched: fix race in mirred device removal 

This fixes hang when target device of mirred packet classifier
action is removed.

If a mirror or redirection action is configured to cause packets
to go to another device, the classifier holds a ref count, but was assuming
the adminstrator cleaned up all redirections before removing. The fix
is to add a notifier and cleanup during unregister.

The new list is implicitly protected by RTNL mutex because
it is held during filter add/delete as well as notifier.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
stephen hemminger 2010-07-22 18:45:04 +00:00 committed by David S. Miller
parent 76ac21f5ef
commit 3b87956ea6
2 changed files with 41 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/net/tc_act/tc_mirred.h
View File

@ -9,6 +9,7 @@ struct tcf_mirred {
int tcfm_ifindex;
int tcfm_ok_push;
struct net_device *tcfm_dev;
struct list_head tcfm_list;
};
#define to_mirred(pc) \
container_of(pc, struct tcf_mirred, common)

43
net/sched/act_mirred.c
View File

@ -33,6 +33,7 @@
static struct tcf_common *tcf_mirred_ht[MIRRED_TAB_MASK + 1];
static u32 mirred_idx_gen;
static DEFINE_RWLOCK(mirred_lock);
static LIST_HEAD(mirred_list);
static struct tcf_hashinfo mirred_hash_info = {
.htab = tcf_mirred_ht,
@ -47,7 +48,9 @@ static inline int tcf_mirred_release(struct tcf_mirred *m, int bind)
m->tcf_bindcnt--;
m->tcf_refcnt--;
if(!m->tcf_bindcnt && m->tcf_refcnt <= 0) {
dev_put(m->tcfm_dev);
list_del(&m->tcfm_list);
if (m->tcfm_dev)
dev_put(m->tcfm_dev);
tcf_hash_destroy(&m->common, &mirred_hash_info);
return 1;
}
@ -134,8 +137,10 @@ static int tcf_mirred_init(struct nlattr *nla, struct nlattr *est,
m->tcfm_ok_push = ok_push;
}
spin_unlock_bh(&m->tcf_lock);
if (ret == ACT_P_CREATED)
if (ret == ACT_P_CREATED) {
list_add(&m->tcfm_list, &mirred_list);
tcf_hash_insert(pc, &mirred_hash_info);
}
return ret;
}
@ -162,9 +167,14 @@ static int tcf_mirred(struct sk_buff *skb, struct tc_action *a,
m->tcf_tm.lastuse = jiffies;
dev = m->tcfm_dev;
if (!dev) {
printk_once(KERN_NOTICE "tc mirred: target device is gone\n");
goto out;
}
if (!(dev->flags & IFF_UP)) {
if (net_ratelimit())
pr_notice("tc mirred to Houston: device %s is gone!\n",
pr_notice("tc mirred to Houston: device %s is down\n",
dev->name);
goto out;
}
@ -232,6 +242,28 @@ nla_put_failure:
return -1;
}
static int mirred_device_event(struct notifier_block *unused,
unsigned long event, void *ptr)
{
struct net_device *dev = ptr;
struct tcf_mirred *m;
if (event == NETDEV_UNREGISTER)
list_for_each_entry(m, &mirred_list, tcfm_list) {
if (m->tcfm_dev == dev) {
dev_put(dev);
m->tcfm_dev = NULL;
}
}
return NOTIFY_DONE;
}
static struct notifier_block mirred_device_notifier = {
.notifier_call = mirred_device_event,
};
static struct tc_action_ops act_mirred_ops = {
.kind = "mirred",
.hinfo = &mirred_hash_info,
@ -252,12 +284,17 @@ MODULE_LICENSE("GPL");
static int __init mirred_init_module(void)
{
int err = register_netdevice_notifier(&mirred_device_notifier);
if (err)
return err;
pr_info("Mirror/redirect action on\n");
return tcf_register_action(&act_mirred_ops);
}
static void __exit mirred_cleanup_module(void)
{
unregister_netdevice_notifier(&mirred_device_notifier);
tcf_unregister_action(&act_mirred_ops);
}