diff options
| author | Stanislav Kinsbursky <skinsbursky@parallels.com> | 2013-06-26 10:15:14 +0400 |
|---|---|---|
| committer | Trond Myklebust <Trond.Myklebust@netapp.com> | 2013-06-28 23:42:02 +0400 |
| commit | adb6fa7ffe9031857ec14b8aab75c9ab65556cbc (patch) | |
| tree | 4d13bd7bf95d0c24478e95f429d6b4e6bbf5a6a5 | |
| parent | 384816051ca9125cd54750e59c780c2a2655fa4f (diff) | |
| download | linux-adb6fa7ffe9031857ec14b8aab75c9ab65556cbc.tar.xz | |
SUNRPC: fix races on PipeFS UMOUNT notifications
CPU#0 CPU#1
----------------------------- -----------------------------
rpc_kill_sb
sn->pipefs_sb = NULL rpc_release_client
(UMOUNT_EVENT) rpc_free_auth
rpc_pipefs_event
rpc_get_client_for_event
!atomic_inc_not_zero(cl_count)
<skip the client>
atomic_inc(cl_count)
rpc_free_client
rpc_clnt_remove_pipedir
<skip client dir removing>
To fix this, this patch does the following:
1) Calls RPC_PIPEFS_UMOUNT notification with sn->pipefs_sb_lock being held.
2) Removes SUNRPC client from the list AFTER pipes destroying.
3) Doesn't hold RPC client on notification: if client in the list, then it
can't be destroyed while sn->pipefs_sb_lock in hold by notification caller.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
| -rw-r--r-- | net/sunrpc/clnt.c | 5 | ||||
| -rw-r--r-- | net/sunrpc/rpc_pipe.c | 2 |
2 files changed, 2 insertions, 5 deletions
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index b827a4b91975..41f180c5a498 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -236,8 +236,6 @@ static struct rpc_clnt *rpc_get_client_for_event(struct net *net, int event) continue; if (rpc_clnt_skip_event(clnt, event)) continue; - if (atomic_inc_not_zero(&clnt->cl_count) == 0) - continue; spin_unlock(&sn->rpc_client_lock); return clnt; } @@ -254,7 +252,6 @@ static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event, while ((clnt = rpc_get_client_for_event(sb->s_fs_info, event))) { error = __rpc_pipefs_event(clnt, event, sb); - rpc_release_client(clnt); if (error) break; } @@ -641,8 +638,8 @@ rpc_free_client(struct rpc_clnt *clnt) rcu_dereference(clnt->cl_xprt)->servername); if (clnt->cl_parent != clnt) rpc_release_client(clnt->cl_parent); - rpc_unregister_client(clnt); rpc_clnt_remove_pipedir(clnt); + rpc_unregister_client(clnt); rpc_free_iostats(clnt->cl_metrics); kfree(clnt->cl_principal); clnt->cl_metrics = NULL; diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c index e02823bdfe98..4679df5a6d50 100644 --- a/net/sunrpc/rpc_pipe.c +++ b/net/sunrpc/rpc_pipe.c @@ -1166,12 +1166,12 @@ static void rpc_kill_sb(struct super_block *sb) goto out; } sn->pipefs_sb = NULL; - mutex_unlock(&sn->pipefs_sb_lock); dprintk("RPC: sending pipefs UMOUNT notification for net %p%s\n", net, NET_NAME(net)); blocking_notifier_call_chain(&rpc_pipefs_notifier_list, RPC_PIPEFS_UMOUNT, sb); + mutex_unlock(&sn->pipefs_sb_lock); put_net(net); out: kill_litter_super(sb); |