From 200b916f3575bdf11609cb447661b8d5957b0bbf Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Mon, 12 May 2014 15:11:20 -0700 Subject: [PATCH] rtnetlink: wait for unregistering devices in rtnl_link_unregister() From: Cong Wang commit 50624c934db18ab90 (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 Cc: David S. Miller Signed-off-by: Cong Wang Signed-off-by: Cong Wang Signed-off-by: David S. Miller --- include/linux/rtnetlink.h | 5 +++++ net/core/dev.c | 2 +- net/core/net_namespace.c | 2 +- net/core/rtnetlink.c | 33 ++++++++++++++++++++++++++++++++- 4 files changed, 39 insertions(+), 3 deletions(-) diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h index 8e3e66a..953937e 100644 --- a/include/linux/rtnetlink.h +++ b/include/linux/rtnetlink.h @@ -4,6 +4,7 @@ #include #include +#include #include 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 int rtnl_trylock(void); extern int rtnl_is_locked(void); + +extern wait_queue_head_t netdev_unregistering_wq; +extern struct mutex net_mutex; + #ifdef CONFIG_PROVE_LOCKING extern int lockdep_rtnl_is_held(void); #else diff --git a/net/core/dev.c b/net/core/dev.c index c619b86..6da649b 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5541,7 +5541,7 @@ static int dev_new_index(struct net *net) /* Delayed registration/unregisteration */ 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) { diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index 81d3a9a..7c8ffd9 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -24,7 +24,7 @@ static LIST_HEAD(pernet_list); static struct list_head *first_device = &pernet_list; -static DEFINE_MUTEX(net_mutex); +DEFINE_MUTEX(net_mutex); LIST_HEAD(net_namespace_list); EXPORT_SYMBOL_GPL(net_namespace_list); diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 9837beb..2d8d8fc 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -353,15 +353,46 @@ void __rtnl_link_unregister(struct rtnl_link_ops *ops) } 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. * @ops: struct rtnl_link_ops * to unregister */ 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_unlock(); + mutex_unlock(&net_mutex); } EXPORT_SYMBOL_GPL(rtnl_link_unregister); -- 2.7.4