SUNRPC: fix races on PipeFS MOUNT notifications
Below are races, when RPC client can be created without PiepFS dentries
CPU#0 CPU#1
----------------------------- -----------------------------
rpc_new_client rpc_fill_super
rpc_setup_pipedir
mutex_lock(&sn->pipefs_sb_lock)
rpc_get_sb_net == NULL
(no per-net PipeFS superblock)
sn->pipefs_sb = sb;
notifier_call_chain(MOUNT)
(client is not in the list)
rpc_register_client
(client without pipes dentries)
To fix this patch:
1) makes PipeFS mount notification call with pipefs_sb_lock being held.
2) releases pipefs_sb_lock on new SUNRPC client creation only after
registration.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 5a750b9c3..b827a4b 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -157,20 +157,15 @@
}
static int
-rpc_setup_pipedir(struct rpc_clnt *clnt, const char *dir_name)
+rpc_setup_pipedir(struct rpc_clnt *clnt, const char *dir_name,
+ struct super_block *pipefs_sb)
{
- struct net *net = rpc_net_ns(clnt);
- struct super_block *pipefs_sb;
struct dentry *dentry;
clnt->cl_dentry = NULL;
if (dir_name == NULL)
return 0;
- pipefs_sb = rpc_get_sb_net(net);
- if (!pipefs_sb)
- return 0;
dentry = rpc_setup_pipedir_sb(pipefs_sb, clnt, dir_name);
- rpc_put_sb_net(net);
if (IS_ERR(dentry))
return PTR_ERR(dentry);
clnt->cl_dentry = dentry;
@@ -296,6 +291,7 @@
struct rpc_clnt *clnt = NULL;
struct rpc_auth *auth;
int err;
+ struct super_block *pipefs_sb;
/* sanity check the name before trying to print it */
dprintk("RPC: creating %s client for %s (xprt %p)\n",
@@ -354,9 +350,12 @@
atomic_set(&clnt->cl_count, 1);
- err = rpc_setup_pipedir(clnt, program->pipe_dir_name);
- if (err < 0)
- goto out_no_path;
+ pipefs_sb = rpc_get_sb_net(rpc_net_ns(clnt));
+ if (pipefs_sb) {
+ err = rpc_setup_pipedir(clnt, program->pipe_dir_name, pipefs_sb);
+ if (err)
+ goto out_no_path;
+ }
auth = rpcauth_create(args->authflavor, clnt);
if (IS_ERR(auth)) {
@@ -369,11 +368,16 @@
/* save the nodename */
rpc_clnt_set_nodename(clnt, utsname()->nodename);
rpc_register_client(clnt);
+ if (pipefs_sb)
+ rpc_put_sb_net(rpc_net_ns(clnt));
return clnt;
out_no_auth:
- rpc_clnt_remove_pipedir(clnt);
+ if (pipefs_sb)
+ __rpc_clnt_remove_pipedir(clnt);
out_no_path:
+ if (pipefs_sb)
+ rpc_put_sb_net(rpc_net_ns(clnt));
kfree(clnt->cl_principal);
out_no_principal:
rpc_free_iostats(clnt->cl_metrics);