linux-kernel - [PATCH 12/12] can: kvaser_usb_leaf: Fix bogus restart events

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Message-Id: <20220516134748.3724796-13-anssi.hannula@bitwise.fi>
Date:   Mon, 16 May 2022 16:47:48 +0300
From:   Anssi Hannula <anssi.hannula@...wise.fi>
To:     Jimmy Assarsson <extja@...ser.com>
Cc:     linux-can@...r.kernel.org, Marc Kleine-Budde <mkl@...gutronix.de>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 12/12] can: kvaser_usb_leaf: Fix bogus restart events

When auto-restart is enabled, the kvaser_usb_leaf driver considers
transition from any state >= CAN_STATE_BUS_OFF as a bus-off recovery
event (restart).

However, these events may occur at interface startup time before
kvaser_usb_open() has set the state to CAN_STATE_ERROR_ACTIVE, causing
restarts counter to increase and CAN_ERR_RESTARTED to be sent despite no
actual restart having occurred.

Fix that by making the auto-restart condition checks more strict so that
they only trigger when the interface was actually in the BUS_OFF state.

Fixes: 080f40a6fa28 ("can: kvaser_usb: Add support for Kvaser CAN/USB devices")
Signed-off-by: Anssi Hannula <anssi.hannula@...wise.fi>
---
 drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c b/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
index 4125074c7066..b280d315673f 100644
--- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
+++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
@@ -735,7 +735,7 @@ static void kvaser_usb_leaf_tx_acknowledge(const struct kvaser_usb *dev,
 	context = &priv->tx_contexts[tid % dev->max_tx_urbs];
 
 	/* Sometimes the state change doesn't come after a bus-off event */
-	if (priv->can.restart_ms && priv->can.state >= CAN_STATE_BUS_OFF) {
+	if (priv->can.restart_ms && priv->can.state == CAN_STATE_BUS_OFF) {
 		struct sk_buff *skb;
 		struct can_frame *cf;
 
@@ -852,7 +852,7 @@ kvaser_usb_leaf_rx_error_update_can_state(struct kvaser_usb_net_priv *priv,
 	}
 
 	if (priv->can.restart_ms &&
-	    cur_state >= CAN_STATE_BUS_OFF &&
+	    cur_state == CAN_STATE_BUS_OFF &&
 	    new_state < CAN_STATE_BUS_OFF)
 		priv->can.can_stats.restarts++;
 
@@ -945,7 +945,7 @@ static void kvaser_usb_leaf_rx_error(const struct kvaser_usb *dev,
 		}
 
 		if (priv->can.restart_ms &&
-		    old_state >= CAN_STATE_BUS_OFF &&
+		    old_state == CAN_STATE_BUS_OFF &&
 		    new_state < CAN_STATE_BUS_OFF) {
 			cf->can_id |= CAN_ERR_RESTARTED;
 			netif_carrier_on(priv->netdev);
-- 
2.34.1