netdev - [PATCH net-next 21/29] can: slcan: do not report txerr and rxerr during bus-off

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Date:   Wed, 20 Jul 2022 10:10:26 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, linux-can@...r.kernel.org,
        kernel@...gutronix.de,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>,
        Dario Binacchi <dario.binacchi@...rulasolutions.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH net-next 21/29] can: slcan: do not report txerr and rxerr during bus-off

From: Vincent Mailhol <mailhol.vincent@...adoo.fr>

During bus off, the error count is greater than 255 and can not fit in
a u8.

alloc_can_err_skb() already sets cf to NULL if the allocation fails [1],
so the redundant cf = NULL assignment gets removed.

[1] https://elixir.bootlin.com/linux/latest/source/drivers/net/can/dev/skb.c#L187

Fixes: 0a9cdcf098a4 ("can: slcan: extend the protocol with CAN state info")
Link: https://lore.kernel.org/all/20220719143550.3681-5-mailhol.vincent@wanadoo.fr
CC: Dario Binacchi <dario.binacchi@...rulasolutions.com>
Signed-off-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/slcan/slcan-core.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c
index 057b211f3e7f..dfd1baba4130 100644
--- a/drivers/net/can/slcan/slcan-core.c
+++ b/drivers/net/can/slcan/slcan-core.c
@@ -306,19 +306,17 @@ static void slc_bump_state(struct slcan *sl)
 		return;
 
 	skb = alloc_can_err_skb(dev, &cf);
-	if (skb) {
-		cf->data[6] = txerr;
-		cf->data[7] = rxerr;
-	} else {
-		cf = NULL;
-	}
 
 	tx_state = txerr >= rxerr ? state : 0;
 	rx_state = txerr <= rxerr ? state : 0;
 	can_change_state(dev, cf, tx_state, rx_state);
 
-	if (state == CAN_STATE_BUS_OFF)
+	if (state == CAN_STATE_BUS_OFF) {
 		can_bus_off(dev);
+	} else if (skb) {
+		cf->data[6] = txerr;
+		cf->data[7] = rxerr;
+	}
 
 	if (skb)
 		netif_rx(skb);
-- 
2.35.1