[PATCH 3.16 203/305] can: at91_can: RX queue could get stuck at high bus load

Ben Hutchings
2016-08-14T10:58:25Z

From: Wolfgang Grandegger <wg@grandegger.com>

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>
---
drivers/net/can/at91_can.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/net/can/at91_can.c
+++ b/drivers/net/can/at91_can.c
@@ -734,9 +734,10 @@ static int at91_poll_rx(struct net_devic

/* 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;