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Commit 3b87956e authored by stephen hemminger's avatar stephen hemminger Committed by David S. Miller
Browse files

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: default avatarStephen Hemminger <shemminger@vyatta.com>
Acked-by: default avatarJamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 76ac21f5

include/net/tc_act/tc_mirred.h

+1 −0
Original line number Diff line number Diff line
@@ -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)

net/sched/act_mirred.c

+40 −3
Original line number Diff line number Diff line
@@ -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,
@@ -47,6 +48,8 @@ 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) {

			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);

}