staging: lustre: avoid race during lnet acceptor thread termination

This patch will avoid potential race, around socket sleepers
wait list, during acceptor thread termination and using
sk_callback_lock RW-Lock protection.
Signed-off-by: Bruno Faccini <bruno.faccini@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6476
Reviewed-on: http://review.whamcloud.com/14503Reviewed-by: Amir Shehata <amir.shehata@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lnet/lnet/acceptor.c

@@ -488,11 +488,17 @@ lnet_acceptor_start(void)
 void
 lnet_acceptor_stop(void)
 {
+	struct sock *sk;
+
 	if (lnet_acceptor_state.pta_shutdown) /* not running */
 		return;
 
 	lnet_acceptor_state.pta_shutdown = 1;
-	wake_up_all(sk_sleep(lnet_acceptor_state.pta_sock->sk));
+
+	sk = lnet_acceptor_state.pta_sock->sk;
+
+	/* awake any sleepers using safe method */
+	sk->sk_state_change(sk);
 
 	/* block until acceptor signals exit */
 	wait_for_completion(&lnet_acceptor_state.pta_signal);