Index: uipc_socket.c
===================================================================
--- uipc_socket.c	(revision 195257)
+++ uipc_socket.c	(working copy)
@@ -2882,8 +2882,10 @@
 {
 	int revents = 0;
 
-	SOCKBUF_LOCK(&so->so_snd);
-	SOCKBUF_LOCK(&so->so_rcv);
+	if (events & (POLLOUT | POLLWRNORM))
+		SOCKBUF_LOCK(&so->so_snd);
+	if (events & ~(POLLOUT | POLLWRNORM))
+		SOCKBUF_LOCK(&so->so_rcv);
 	if (events & (POLLIN | POLLRDNORM))
 		if (soreadable(so))
 			revents |= events & (POLLIN | POLLRDNORM);
@@ -2915,8 +2917,10 @@
 		}
 	}
 
-	SOCKBUF_UNLOCK(&so->so_rcv);
-	SOCKBUF_UNLOCK(&so->so_snd);
+	if (events & ~(POLLOUT | POLLWRNORM))
+		SOCKBUF_UNLOCK(&so->so_rcv);
+	if (events & (POLLOUT | POLLWRNORM))
+		SOCKBUF_UNLOCK(&so->so_snd);
 	return (revents);
 }