* [PATCH] netns: Simplify the network namespace list locking rules. [not found] <46F3C777.7070103@sw.ru> @ 2007-09-27 3:54 ` Eric W. Biederman 0 siblings, 0 replies; 4+ messages in thread From: Eric W. Biederman @ 2007-09-27 3:54 UTC (permalink / raw) To: David Miller Cc: Daniel Lezcano, Benjamin Thery, Kirill Korotaev, Denis V. Lunev, Linux Containers, netdev Denis V. Lunev <den@sw.ru> noticed that the locking rules for the network namespace list are over complicated and broken. In particular the current register_netdev_notifier currently does not take any lock making the for_each_net iteration racy with network namespace creation and destruction. Oops. The fact that we need to use for_each_net in rtnl_unlock() when the rtnetlink support becomes per network namespace makes designing the proper locking tricky. In addition we need to be able to call rtnl_lock() and rtnl_unlock() when we have the net_mutex held. After thinking about it and looking at the alternatives carefully it looks like the simplest and most maintainable solution is to remove net_list_mutex altogether, and to use the rtnl_mutex instead. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> --- include/net/net_namespace.h | 3 --- net/core/net_namespace.c | 23 ++++++----------------- 2 files changed, 6 insertions(+), 20 deletions(-) diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index 13b0e3b..934c840 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -96,9 +96,6 @@ static inline void release_net(struct net *net) #endif } -extern void net_lock(void); -extern void net_unlock(void); - #define for_each_net(VAR) \ list_for_each_entry(VAR, &net_namespace_list, list) diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index e478e35..0e0ca6d 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -15,7 +15,6 @@ static LIST_HEAD(pernet_list); static struct list_head *first_device = &pernet_list; static DEFINE_MUTEX(net_mutex); -static DEFINE_MUTEX(net_list_mutex); LIST_HEAD(net_namespace_list); static struct kmem_cache *net_cachep; @@ -23,16 +22,6 @@ static struct kmem_cache *net_cachep; struct net init_net; EXPORT_SYMBOL_GPL(init_net); -void net_lock(void) -{ - mutex_lock(&net_list_mutex); -} - -void net_unlock(void) -{ - mutex_unlock(&net_list_mutex); -} - static struct net *net_alloc(void) { return kmem_cache_alloc(net_cachep, GFP_KERNEL); @@ -62,9 +51,9 @@ static void cleanup_net(struct work_struct *work) mutex_lock(&net_mutex); /* Don't let anyone else find us. */ - net_lock(); + rtnl_lock(); list_del(&net->list); - net_unlock(); + rtnl_unlock(); /* Run all of the network namespace exit methods */ list_for_each_entry_reverse(ops, &pernet_list, list) { @@ -151,9 +140,9 @@ struct net *copy_net_ns(unsigned long flags, struct net *old_net) if (err) goto out_unlock; - net_lock(); + rtnl_lock(); list_add_tail(&new_net->list, &net_namespace_list); - net_unlock(); + rtnl_unlock(); out_unlock: @@ -178,9 +167,9 @@ static int __init net_ns_init(void) mutex_lock(&net_mutex); err = setup_net(&init_net); - net_lock(); + rtnl_lock(); list_add_tail(&init_net.list, &net_namespace_list); - net_unlock(); + rtnl_unlock(); mutex_unlock(&net_mutex); if (err) -- 1.5.3.rc6.17.g1911 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH] netns: Simplify the network namespace list locking rules. @ 2007-09-27 3:54 ` Eric W. Biederman 0 siblings, 0 replies; 4+ messages in thread From: Eric W. Biederman @ 2007-09-27 3:54 UTC (permalink / raw) To: David Miller Cc: Daniel Lezcano, Benjamin Thery, Kirill Korotaev, Denis V. Lunev, Linux Containers, netdev Denis V. Lunev <den@sw.ru> noticed that the locking rules for the network namespace list are over complicated and broken. In particular the current register_netdev_notifier currently does not take any lock making the for_each_net iteration racy with network namespace creation and destruction. Oops. The fact that we need to use for_each_net in rtnl_unlock() when the rtnetlink support becomes per network namespace makes designing the proper locking tricky. In addition we need to be able to call rtnl_lock() and rtnl_unlock() when we have the net_mutex held. After thinking about it and looking at the alternatives carefully it looks like the simplest and most maintainable solution is to remove net_list_mutex altogether, and to use the rtnl_mutex instead. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> --- include/net/net_namespace.h | 3 --- net/core/net_namespace.c | 23 ++++++----------------- 2 files changed, 6 insertions(+), 20 deletions(-) diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index 13b0e3b..934c840 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -96,9 +96,6 @@ static inline void release_net(struct net *net) #endif } -extern void net_lock(void); -extern void net_unlock(void); - #define for_each_net(VAR) \ list_for_each_entry(VAR, &net_namespace_list, list) diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index e478e35..0e0ca6d 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -15,7 +15,6 @@ static LIST_HEAD(pernet_list); static struct list_head *first_device = &pernet_list; static DEFINE_MUTEX(net_mutex); -static DEFINE_MUTEX(net_list_mutex); LIST_HEAD(net_namespace_list); static struct kmem_cache *net_cachep; @@ -23,16 +22,6 @@ static struct kmem_cache *net_cachep; struct net init_net; EXPORT_SYMBOL_GPL(init_net); -void net_lock(void) -{ - mutex_lock(&net_list_mutex); -} - -void net_unlock(void) -{ - mutex_unlock(&net_list_mutex); -} - static struct net *net_alloc(void) { return kmem_cache_alloc(net_cachep, GFP_KERNEL); @@ -62,9 +51,9 @@ static void cleanup_net(struct work_struct *work) mutex_lock(&net_mutex); /* Don't let anyone else find us. */ - net_lock(); + rtnl_lock(); list_del(&net->list); - net_unlock(); + rtnl_unlock(); /* Run all of the network namespace exit methods */ list_for_each_entry_reverse(ops, &pernet_list, list) { @@ -151,9 +140,9 @@ struct net *copy_net_ns(unsigned long flags, struct net *old_net) if (err) goto out_unlock; - net_lock(); + rtnl_lock(); list_add_tail(&new_net->list, &net_namespace_list); - net_unlock(); + rtnl_unlock(); out_unlock: @@ -178,9 +167,9 @@ static int __init net_ns_init(void) mutex_lock(&net_mutex); err = setup_net(&init_net); - net_lock(); + rtnl_lock(); list_add_tail(&init_net.list, &net_namespace_list); - net_unlock(); + rtnl_unlock(); mutex_unlock(&net_mutex); if (err) -- 1.5.3.rc6.17.g1911 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] netns: Simplify the network namespace list locking rules. 2007-09-27 3:54 ` Eric W. Biederman (?) @ 2007-09-27 5:21 ` Denis V. Lunev -1 siblings, 0 replies; 4+ messages in thread From: Denis V. Lunev @ 2007-09-27 5:21 UTC (permalink / raw) To: Eric W. Biederman Cc: David Miller, Daniel Lezcano, Benjamin Thery, Kirill Korotaev, Linux Containers, netdev Eric W. Biederman wrote: > Denis V. Lunev <den@sw.ru> noticed that the locking rules > for the network namespace list are over complicated and broken. > > In particular the current register_netdev_notifier currently > does not take any lock making the for_each_net iteration racy > with network namespace creation and destruction. Oops. > > The fact that we need to use for_each_net in rtnl_unlock() when > the rtnetlink support becomes per network namespace makes designing > the proper locking tricky. In addition we need to be able to call > rtnl_lock() and rtnl_unlock() when we have the net_mutex held. > > After thinking about it and looking at the alternatives carefully > it looks like the simplest and most maintainable solution is > to remove net_list_mutex altogether, and to use the rtnl_mutex instead. > > Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Denis V. Lunev <den@openvz.org> ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] netns: Simplify the network namespace list locking rules. 2007-09-27 3:54 ` Eric W. Biederman (?) (?) @ 2007-09-27 5:40 ` David Miller -1 siblings, 0 replies; 4+ messages in thread From: David Miller @ 2007-09-27 5:40 UTC (permalink / raw) To: ebiederm; +Cc: dlezcano, benjamin.thery, dev, den, containers, netdev From: ebiederm@xmission.com (Eric W. Biederman) Date: Wed, 26 Sep 2007 21:54:47 -0600 > > Denis V. Lunev <den@sw.ru> noticed that the locking rules > for the network namespace list are over complicated and broken. > > In particular the current register_netdev_notifier currently > does not take any lock making the for_each_net iteration racy > with network namespace creation and destruction. Oops. > > The fact that we need to use for_each_net in rtnl_unlock() when > the rtnetlink support becomes per network namespace makes designing > the proper locking tricky. In addition we need to be able to call > rtnl_lock() and rtnl_unlock() when we have the net_mutex held. > > After thinking about it and looking at the alternatives carefully > it looks like the simplest and most maintainable solution is > to remove net_list_mutex altogether, and to use the rtnl_mutex instead. > > Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Applied, thanks Eric. ^ permalink raw reply [flat|nested] 4+ messages in thread
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2007-09-27 3:54 ` [PATCH] netns: Simplify the network namespace list locking rules Eric W. Biederman
2007-09-27 3:54 ` Eric W. Biederman
2007-09-27 5:21 ` Denis V. Lunev
2007-09-27 5:40 ` David Miller
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