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rtnetlink: wait for unregistering devices in rtnl_link_unregister()

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From: Cong Wang <cwang@twopensource.com>

commit 50624c934d (net: Delay default_device_exit_batch until no
devices are unregistering) introduced rtnl_lock_unregistering() for
default_device_exit_batch(). Same race could happen we when rmmod a driver
which calls rtnl_link_unregister() as we call dev->destructor without rtnl
lock.

For long term, I think we should clean up the mess of netdev_run_todo()
and net namespce exit code.

Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Cong Wang <cwang@twopensource.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Cong Wang 2014-05-12 15:11:20 -07:00 • committed by David S. Miller
parent e84d2f8d2a
commit 200b916f35
4 changed files with 39 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

5
include/linux/rtnetlink.h
View file

@ -4,6 +4,7 @@
#include <linux/mutex.h> #include <linux/mutex.h>
#include <linux/netdevice.h> #include <linux/netdevice.h>
#include <linux/wait.h>
#include <uapi/linux/rtnetlink.h> #include <uapi/linux/rtnetlink.h>
extern int rtnetlink_send(struct sk_buff *skb, struct net *net, u32 pid, u32 group, int echo); extern int rtnetlink_send(struct sk_buff *skb, struct net *net, u32 pid, u32 group, int echo);
@ -22,6 +23,10 @@ extern void rtnl_lock(void);
extern void rtnl_unlock(void); extern void rtnl_unlock(void);
extern int rtnl_trylock(void); extern int rtnl_trylock(void);
extern int rtnl_is_locked(void); extern int rtnl_is_locked(void);
extern wait_queue_head_t netdev_unregistering_wq;
extern struct mutex net_mutex;
#ifdef CONFIG_PROVE_LOCKING #ifdef CONFIG_PROVE_LOCKING
extern int lockdep_rtnl_is_held(void); extern int lockdep_rtnl_is_held(void);
#else #else

2
net/core/dev.c
View file

@ -5541,7 +5541,7 @@ static int dev_new_index(struct net *net)
/* Delayed registration/unregisteration */ /* Delayed registration/unregisteration */
static LIST_HEAD(net_todo_list); static LIST_HEAD(net_todo_list);
static DECLARE_WAIT_QUEUE_HEAD(netdev_unregistering_wq); DECLARE_WAIT_QUEUE_HEAD(netdev_unregistering_wq);
static void net_set_todo(struct net_device *dev) static void net_set_todo(struct net_device *dev)
{ {

2
net/core/net_namespace.c
View file

@ -24,7 +24,7 @@
static LIST_HEAD(pernet_list); static LIST_HEAD(pernet_list);
static struct list_head *first_device = &pernet_list; static struct list_head *first_device = &pernet_list;
static DEFINE_MUTEX(net_mutex); DEFINE_MUTEX(net_mutex);
LIST_HEAD(net_namespace_list); LIST_HEAD(net_namespace_list);
EXPORT_SYMBOL_GPL(net_namespace_list); EXPORT_SYMBOL_GPL(net_namespace_list);

33
net/core/rtnetlink.c
View file

@ -353,15 +353,46 @@ void __rtnl_link_unregister(struct rtnl_link_ops *ops)
} }
EXPORT_SYMBOL_GPL(__rtnl_link_unregister); EXPORT_SYMBOL_GPL(__rtnl_link_unregister);
/* Return with the rtnl_lock held when there are no network
* devices unregistering in any network namespace.
*/
static void rtnl_lock_unregistering_all(void)
{
struct net *net;
bool unregistering;
DEFINE_WAIT(wait);
for (;;) {
prepare_to_wait(&netdev_unregistering_wq, &wait,
TASK_UNINTERRUPTIBLE);
unregistering = false;
rtnl_lock();
for_each_net(net) {
if (net->dev_unreg_count > 0) {
unregistering = true;
break;
}
}
if (!unregistering)
break;
__rtnl_unlock();
schedule();
}
finish_wait(&netdev_unregistering_wq, &wait);
}
/** /**
* rtnl_link_unregister - Unregister rtnl_link_ops from rtnetlink. * rtnl_link_unregister - Unregister rtnl_link_ops from rtnetlink.
* @ops: struct rtnl_link_ops * to unregister * @ops: struct rtnl_link_ops * to unregister
*/ */
void rtnl_link_unregister(struct rtnl_link_ops *ops) void rtnl_link_unregister(struct rtnl_link_ops *ops)
{ {
rtnl_lock(); /* Close the race with cleanup_net() */
mutex_lock(&net_mutex);
rtnl_lock_unregistering_all();
__rtnl_link_unregister(ops); __rtnl_link_unregister(ops);
rtnl_unlock(); rtnl_unlock();
mutex_unlock(&net_mutex);
} }
EXPORT_SYMBOL_GPL(rtnl_link_unregister); EXPORT_SYMBOL_GPL(rtnl_link_unregister);