netdev - [PATCH v2 net] af_unix: Support POLLPRI for OOB.

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Message-ID: <20220315054801.72035-1-kuniyu@amazon.co.jp>
Date:   Tue, 15 Mar 2022 14:48:01 +0900
From:   Kuniyuki Iwashima <kuniyu@...zon.co.jp>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Rao Shoaib <Rao.Shoaib@...cle.com>
CC:     Kuniyuki Iwashima <kuniyu@...zon.co.jp>,
        Kuniyuki Iwashima <kuni1840@...il.com>,
        <netdev@...r.kernel.org>
Subject: [PATCH v2 net] af_unix: Support POLLPRI for OOB.

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.

v2:
  - Add READ_ONCE() to avoid a race reported by KCSAN (Eric)
  - Add IS_ENABLED(CONFIG_AF_UNIX_OOB) (Shoaib)

v1:
https://lore.kernel.org/netdev/20220314052110.53634-1-kuniyu@amazon.co.jp/

Fixes: 314001f0bf92 ("af_unix: Add OOB support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.co.jp>
---
 net/unix/af_unix.c                                  | 10 +++++++---
 tools/testing/selftests/net/af_unix/test_unix_oob.c |  6 +++---
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index c19569819866..9cf1137ae174 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2049,7 +2049,7 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
  */
 #define UNIX_SKB_FRAGS_SZ (PAGE_SIZE << get_order(32768))
 
-#if (IS_ENABLED(CONFIG_AF_UNIX_OOB))
+#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
 static int queue_oob(struct socket *sock, struct msghdr *msg, struct sock *other)
 {
 	struct unix_sock *ousk = unix_sk(other);
@@ -2115,7 +2115,7 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
 
 	err = -EOPNOTSUPP;
 	if (msg->msg_flags & MSG_OOB) {
-#if (IS_ENABLED(CONFIG_AF_UNIX_OOB))
+#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
 		if (len)
 			len--;
 		else
@@ -2186,7 +2186,7 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
 		sent += size;
 	}
 
-#if (IS_ENABLED(CONFIG_AF_UNIX_OOB))
+#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
 	if (msg->msg_flags & MSG_OOB) {
 		err = queue_oob(sock, msg, other);
 		if (err)
@@ -3139,6 +3139,10 @@ static __poll_t unix_poll(struct file *file, struct socket *sock, poll_table *wa
 		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) &&
diff --git a/tools/testing/selftests/net/af_unix/test_unix_oob.c b/tools/testing/selftests/net/af_unix/test_unix_oob.c
index 3dece8b29253..b57e91e1c3f2 100644
--- 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 != '@') {
-- 
2.30.2