[PATCH] at91_can: RX queue could get stuck at high bus load

[PATCH] at91_can: RX queue could get stuck at high bus load

[Wolfgang Grandegger]

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

diff --git a/drivers/net/can/at91_can.c b/drivers/net/can/at91_can.c
index 8b3275d..8f5e93c 100644
--- a/drivers/net/can/at91_can.c
+++ b/drivers/net/can/at91_can.c
@@ -712,9 +712,10 @@ 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;
-- 
1.9.1

Re: [PATCH] at91_can: RX queue could get stuck at high bus load

[Marc Kleine-Budde]

[-- Attachment #1.1: Type: text/plain, Size: 747 bytes --]

On 06/13/2016 03:44 PM, Wolfgang Grandegger wrote:
> 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>

Applied to can/master + stable on Cc.

tnx,
Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 455 bytes --]