[PATCH 3.16 220/254] can: af_can: canfd_rcv(): replace WARN_ONCE by pr_warn_once

[Ben Hutchings]

3.16.55-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Marc Kleine-Budde <m...@pengutronix.de>

commit d4689846881d160a4d12a514e991a740bcb5d65a upstream.

If an invalid CANFD frame is received, from a driver or from a tun
interface, a Kernel warning is generated.

This patch replaces the WARN_ONCE by a simple pr_warn_once, so that a
kernel, bootet with panic_on_warn, does not panic. A printk seems to be
more appropriate here.

Reported-by: syzbot+e3b775f40babeff6e...@syzkaller.appspotmail.com
Suggested-by: Dmitry Vyukov <dvyu...@google.com>
Acked-by: Oliver Hartkopp <socket...@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <m...@pengutronix.de>
[bwh: Backported to 3.16:
 - Keep using the 'drop' label, as it has another user
 - Adjust context]
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -742,13 +742,12 @@ static int canfd_rcv(struct sk_buff *skb
        if (unlikely(!net_eq(dev_net(dev), &init_net)))
                goto drop;
 
-       if (WARN_ONCE(dev->type != ARPHRD_CAN ||
-                     skb->len != CANFD_MTU ||
-                     cfd->len > CANFD_MAX_DLEN,
-                     "PF_CAN: dropped non conform CAN FD skbuf: "
-                     "dev type %d, len %d, datalen %d\n",
-                     dev->type, skb->len, cfd->len))
+       if (unlikely(dev->type != ARPHRD_CAN || skb->len != CANFD_MTU ||
+                    cfd->len > CANFD_MAX_DLEN)) {
+               pr_warn_once("PF_CAN: dropped non conform CAN FD skbuf: dev 
type %d, len %d, datalen %d\n",
+                            dev->type, skb->len, cfd->len);
                goto drop;
+       }
 
        can_receive(skb, dev);
        return NET_RX_SUCCESS;