Merge branch 'af_unix-fix-two-data-races-reported-by-kcsan'

Kuniyuki Iwashima says:

====================
af_unix: Fix two data races reported by KCSAN.

KCSAN reported data races around these two fields for AF_UNIX sockets.

  * sk->sk_receive_queue->qlen
  * sk->sk_shutdown

Let's annotate them properly.
====================

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: kuba-moo

net/unix/af_unix.c

@@ -603,7 +603,7 @@ static void unix_release_sock(struct sock *sk, int embrion)
 	/* Clear state */
 	unix_state_lock(sk);
 	sock_orphan(sk);
-	sk->sk_shutdown = SHUTDOWN_MASK;
+	WRITE_ONCE(sk->sk_shutdown, SHUTDOWN_MASK);
 	path	     = u->path;
 	u->path.dentry = NULL;
 	u->path.mnt = NULL;
@@ -628,7 +628,7 @@ static void unix_release_sock(struct sock *sk, int embrion)
 		if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) {
 			unix_state_lock(skpair);
 			/* No more writes */
-			skpair->sk_shutdown = SHUTDOWN_MASK;
+			WRITE_ONCE(skpair->sk_shutdown, SHUTDOWN_MASK);
 			if (!skb_queue_empty(&sk->sk_receive_queue) || embrion)
 				WRITE_ONCE(skpair->sk_err, ECONNRESET);
 			unix_state_unlock(skpair);
@@ -1442,7 +1442,7 @@ static long unix_wait_for_peer(struct sock *other, long timeo)
 
 	sched = !sock_flag(other, SOCK_DEAD) &&
 		!(other->sk_shutdown & RCV_SHUTDOWN) &&
-		unix_recvq_full(other);
+		unix_recvq_full_lockless(other);
 
 	unix_state_unlock(other);
 
@@ -3008,7 +3008,7 @@ static int unix_shutdown(struct socket *sock, int mode)
 	++mode;
 
 	unix_state_lock(sk);
-	sk->sk_shutdown |= mode;
+	WRITE_ONCE(sk->sk_shutdown, sk->sk_shutdown | mode);
 	other = unix_peer(sk);
 	if (other)
 		sock_hold(other);
@@ -3028,7 +3028,7 @@ static int unix_shutdown(struct socket *sock, int mode)
 		if (mode&SEND_SHUTDOWN)
 			peer_mode |= RCV_SHUTDOWN;
 		unix_state_lock(other);
-		other->sk_shutdown |= peer_mode;
+		WRITE_ONCE(other->sk_shutdown, other->sk_shutdown | peer_mode);
 		unix_state_unlock(other);
 		other->sk_state_change(other);
 		if (peer_mode == SHUTDOWN_MASK)
@@ -3160,16 +3160,18 @@ static __poll_t unix_poll(struct file *file, struct socket *sock, poll_table *wa
 {
 	struct sock *sk = sock->sk;
 	__poll_t mask;
+	u8 shutdown;
 
 	sock_poll_wait(file, sock, wait);
 	mask = 0;
+	shutdown = READ_ONCE(sk->sk_shutdown);
 
 	/* exceptional events? */
 	if (READ_ONCE(sk->sk_err))
 		mask |= EPOLLERR;
-	if (sk->sk_shutdown == SHUTDOWN_MASK)
+	if (shutdown == SHUTDOWN_MASK)
 		mask |= EPOLLHUP;
-	if (sk->sk_shutdown & RCV_SHUTDOWN)
+	if (shutdown & RCV_SHUTDOWN)
 		mask |= EPOLLRDHUP | EPOLLIN | EPOLLRDNORM;
 
 	/* readable? */
@@ -3203,19 +3205,21 @@ static __poll_t unix_dgram_poll(struct file *file, struct socket *sock,
 	struct sock *sk = sock->sk, *other;
 	unsigned int writable;
 	__poll_t mask;
+	u8 shutdown;
 
 	sock_poll_wait(file, sock, wait);
 	mask = 0;
+	shutdown = READ_ONCE(sk->sk_shutdown);
 
 	/* exceptional events? */
 	if (READ_ONCE(sk->sk_err) ||
 	    !skb_queue_empty_lockless(&sk->sk_error_queue))
 		mask |= EPOLLERR |
 			(sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? EPOLLPRI : 0);
 
-	if (sk->sk_shutdown & RCV_SHUTDOWN)
+	if (shutdown & RCV_SHUTDOWN)
 		mask |= EPOLLRDHUP | EPOLLIN | EPOLLRDNORM;
-	if (sk->sk_shutdown == SHUTDOWN_MASK)
+	if (shutdown == SHUTDOWN_MASK)
 		mask |= EPOLLHUP;
 
 	/* readable? */