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authorStanislav Kinsbursky <skinsbursky@parallels.com>2013-06-26 10:15:14 +0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2013-06-28 23:42:02 +0400
commitadb6fa7ffe9031857ec14b8aab75c9ab65556cbc (patch)
tree4d13bd7bf95d0c24478e95f429d6b4e6bbf5a6a5 /net/sunrpc/clnt.c
parent384816051ca9125cd54750e59c780c2a2655fa4f (diff)
downloadlinux-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>
Diffstat (limited to 'net/sunrpc/clnt.c')
-rw-r--r--net/sunrpc/clnt.c5
1 files changed, 1 insertions, 4 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;