[PATCH net] rxrpc: Don't release call mutex on error pointer

[David Howells]

Don't release call mutex at the end of rxrpc_kernel_begin_call() if the
call pointer actually holds an error value.

Fixes: 540b1c48c37a ("rxrpc: Fix deadlock between call creation and 
sendmsg/recvmsg")
Reported-by: Marc Dionne <marc.dio...@auristor.com>
Signed-off-by: David Howells <dhowe...@redhat.com>
---

 net/rxrpc/af_rxrpc.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index 73c980e26581..054e32872808 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -311,10 +311,11 @@ struct rxrpc_call *rxrpc_kernel_begin_call(struct socket 
*sock,
        call = rxrpc_new_client_call(rx, &cp, srx, user_call_ID, tx_total_len,
                                     gfp);
        /* The socket has been unlocked. */
-       if (!IS_ERR(call))
+       if (!IS_ERR(call)) {
                call->notify_rx = notify_rx;
+               mutex_unlock(&call->user_mutex);
+       }
 
-       mutex_unlock(&call->user_mutex);
        _leave(" = %p", call);
        return call;
 }