Patch "can: at91_can: RX queue could get stuck at high bus load" has been added to the 4.4-stable tree

Patch "can: at91_can: RX queue could get stuck at high bus load" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

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

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     can-at91_can-rx-queue-could-get-stuck-at-high-bus-load.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 43200a4480cbbe660309621817f54cbb93907108 Mon Sep 17 00:00:00 2001
From: Wolfgang Grandegger <wg@grandegger.com>
Date: Mon, 13 Jun 2016 15:44:19 +0200
Subject: can: at91_can: RX queue could get stuck at high bus load

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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
@@ -712,9 +712,10 @@ 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;


Patches currently in stable-queue which might be from wg@grandegger.com are

queue-4.4/can-at91_can-rx-queue-could-get-stuck-at-high-bus-load.patch