[syzbot] WARNING: bad unlock balance in rxrpc_do_sendmsg

[Khalid Masum]

Maybe we do not need to lock since no other timer_schedule needs 
it. 

Test if this fixes the issue.
---
#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 568035b01cfb
 net/rxrpc/sendmsg.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index 1d38e279e2ef..640e2ab2cc35 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -51,10 +51,8 @@ static int rxrpc_wait_for_tx_window_intr(struct rxrpc_sock *rx,
 			return sock_intr_errno(*timeo);
 
 		trace_rxrpc_transmit(call, rxrpc_transmit_wait);
-		mutex_unlock(&call->user_mutex);
 		*timeo = schedule_timeout(*timeo);
-		if (mutex_lock_interruptible(&call->user_mutex) < 0)
-			return sock_intr_errno(*timeo);
+		return sock_intr_errno(*timeo);
 	}
 }
 
-- 
2.37.1