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>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/net/can/at91_can.c b/drivers/net/can/at91_can.c
index ab411c3..a42d75c 100644 (file)
--- a/drivers/net/can/at91_can.c
+++ b/drivers/net/can/at91_can.c
@@ -727,9 +727,10 @@ 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;