[PATCH] can: j1939: Replace WARN_ON_ONCE with pr_warn_once() in j1939_sk_queue_activate_next_locked()

[Fedor Pchelkin]

We should warn user-space that it is doing something wrong when trying to
activate sessions with identical parameters but WARN_ON_ONCE macro can not
be used here as it serves a different purpose.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Fedor Pchelkin <pchelkin@xxxxxxxxx>
Signed-off-by: Alexey Khoroshilov <khoroshilov@xxxxxxxxx>
---
 net/can/j1939/socket.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index f5ecfdcf57b2..67e8b50b8bc1 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -178,7 +178,8 @@ static void j1939_sk_queue_activate_next_locked(struct j1939_session *session)
 	if (!first)
 		return;
 
-	if (WARN_ON_ONCE(j1939_session_activate(first))) {
+	if (j1939_session_activate(first)) {
+		pr_warn_once("can: j1939: Identical session is already activated.\n");
 		first->err = -EBUSY;
 		goto activate_next;
 	} else {
-- 
2.25.1