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 535d5dd8d8168fa5dd43ddca86804dd96a775f65..024078c5fb1655e5ce4612879932bad7165e8243 100644 (file)
--- 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;