From: Wolfgang Grandegger <wg@grandegger.com>
Date: Mon, 13 Jun 2016 13:44:19 +0000 (+0200)
Subject: can: at91_can: RX queue could get stuck at high bus load
X-Git-Tag: v3.10.103~33
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=56a5db827f79ab8ed1161d1b2d6d14d2a4d60624;p=thirdparty%2Fkernel%2Fstable.git

can: at91_can: RX queue could get stuck at high bus load

commit 43200a4480cbbe660309621817f54cbb93907108 upstream.

At high bus load it could happen that "at91_poll()" enters with all RX
message boxes filled up. If then at the end the "quota" is exceeded as
well, "rx_next" will not be reset to the first RX mailbox and hence the
interrupts remain disabled.

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Tested-by: Amr Bekhit <amrbekhit@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---

diff --git a/drivers/net/can/at91_can.c b/drivers/net/can/at91_can.c
index 535d5dd8d8168..024078c5fb165 100644
--- a/drivers/net/can/at91_can.c
+++ b/drivers/net/can/at91_can.c
@@ -731,9 +731,10 @@ static int at91_poll_rx(struct net_device *dev, int quota)
 
 	/* upper group completed, look again in lower */
 	if (priv->rx_next > get_mb_rx_low_last(priv) &&
-	    quota > 0 && mb > get_mb_rx_last(priv)) {
+	    mb > get_mb_rx_last(priv)) {
 		priv->rx_next = get_mb_rx_first(priv);
-		goto again;
+		if (quota > 0)
+			goto again;
 	}
 
 	return received;