[PATCH 5.17 1083/1126] af_unix: Support POLLPRI for OOB.

[Greg Kroah-Hartman]

From: Kuniyuki Iwashima <kuniyu@xxxxxxxxxxxx>

commit d9a232d435dcc966738b0f414a86f7edf4f4c8c4 upstream.

The commit 314001f0bf92 ("af_unix: Add OOB support") introduced OOB for
AF_UNIX, but it lacks some changes for POLLPRI.  Let's add the missing
piece.

In the selftest, normal datagrams are sent followed by OOB data, so this
commit replaces `POLLIN | POLLPRI` with just `POLLPRI` in the first test
case.

Fixes: 314001f0bf92 ("af_unix: Add OOB support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/unix/af_unix.c                                  |    4 ++++
 tools/testing/selftests/net/af_unix/test_unix_oob.c |    6 +++---
 2 files changed, 7 insertions(+), 3 deletions(-)

--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -3137,6 +3137,10 @@ static __poll_t unix_poll(struct file *f
 		mask |= EPOLLIN | EPOLLRDNORM;
 	if (sk_is_readable(sk))
 		mask |= EPOLLIN | EPOLLRDNORM;
+#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
+	if (READ_ONCE(unix_sk(sk)->oob_skb))
+		mask |= EPOLLPRI;
+#endif
 
 	/* Connection-based need to check for termination and startup */
 	if ((sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) &&
--- a/tools/testing/selftests/net/af_unix/test_unix_oob.c
+++ b/tools/testing/selftests/net/af_unix/test_unix_oob.c
@@ -218,10 +218,10 @@ main(int argc, char **argv)
 
 	/* Test 1:
 	 * veriyf that SIGURG is
-	 * delivered and 63 bytes are
-	 * read and oob is '@'
+	 * delivered, 63 bytes are
+	 * read, oob is '@', and POLLPRI works.
 	 */
-	wait_for_data(pfd, POLLIN | POLLPRI);
+	wait_for_data(pfd, POLLPRI);
 	read_oob(pfd, &oob);
 	len = read_data(pfd, buf, 1024);
 	if (!signal_recvd || len != 63 || oob != '@') {