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authorEric W. Biederman <ebiederm@xmission.com>2007-09-26 22:40:08 -0700
committerDavid S. Miller <davem@sunset.davemloft.net>2007-10-10 16:52:55 -0700
commitf4618d39a34dab316090263b42cd8799f31ce277 (patch)
tree75db202b492da1797145fde455b0c4c89cf41767
parent32db927686f6d475fc05b6229f82ed576c0c8096 (diff)
[NETNS]: Simplify the network namespace list locking rules.
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> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/net_namespace.h3
-rw-r--r--net/core/net_namespace.c23
2 files changed, 6 insertions, 20 deletions
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 13b0e3b547f..934c840b594 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 e478e353ea6..0e0ca6d06fa 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)