[PATCH 6.6 02/93] can: gs_usb: gs_usb_xmit_callback(): fix handling of failed transmitted URBs

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marc Kleine-Budde <mkl@pengutronix.de>

[ Upstream commit 516a0cd1c03fa266bb67dd87940a209fd4e53ce7 ]

The driver lacks the cleanup of failed transfers of URBs. This reduces the
number of available URBs per error by 1. This leads to reduced performance
and ultimately to a complete stop of the transmission.

If the sending of a bulk URB fails do proper cleanup:
- increase netdev stats
- mark the echo_sbk as free
- free the driver's context and do accounting
- wake the send queue

Closes: https://github.com/candle-usb/candleLight_fw/issues/187
Fixes: d08e973a77d1 ("can: gs_usb: Added support for the GS_USB CAN devices")
Link: https://patch.msgid.link/20251114-gs_usb-fix-usb-callbacks-v1-1-a29b42eacada@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/can/usb/gs_usb.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
index 9bd61fd8e5013..1ba6395a5a667 100644
--- a/drivers/net/can/usb/gs_usb.c
+++ b/drivers/net/can/usb/gs_usb.c
@@ -747,8 +747,21 @@ static void gs_usb_xmit_callback(struct urb *urb)
 	struct gs_can *dev = txc->dev;
 	struct net_device *netdev = dev->netdev;
 
-	if (urb->status)
-		netdev_info(netdev, "usb xmit fail %u\n", txc->echo_id);
+	if (!urb->status)
+		return;
+
+	if (urb->status != -ESHUTDOWN && net_ratelimit())
+		netdev_info(netdev, "failed to xmit URB %u: %pe\n",
+			    txc->echo_id, ERR_PTR(urb->status));
+
+	netdev->stats.tx_dropped++;
+	netdev->stats.tx_errors++;
+
+	can_free_echo_skb(netdev, txc->echo_id, NULL);
+	gs_free_tx_context(txc);
+	atomic_dec(&dev->active_tx_urbs);
+
+	netif_wake_queue(netdev);
 }
 
 static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
-- 
2.51.0