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SubjectRe: [PATCH 06/12] can: kvaser_usb_leaf: Fix TX queue out of sync after restart
On 5/16/22 15:47, Anssi Hannula wrote:
> The TX queue seems to be implicitly flushed by the hardware during
> bus-off or bus-off recovery, but the driver does not reset the TX
> bookkeeping.
>
> Despite not resetting TX bookkeeping the driver still re-enables TX
> queue unconditionally, leading to "cannot find free context" /
> NETDEV_TX_BUSY errors if the TX queue was full at bus-off time.
>
> Fix that by resetting TX bookkeeping on CAN restart.
>
> Also, add an explicit queue flush in case some hardware versions do not
> do that implicitly.

See comment below regarding this.

> Tested with 0bfd:0124 Kvaser Mini PCI Express 2xHS FW 4.18.778.
>
> Fixes: 080f40a6fa28 ("can: kvaser_usb: Add support for Kvaser CAN/USB devices")
> Signed-off-by: Anssi Hannula <anssi.hannula@bitwise.fi>
> ---
> drivers/net/can/usb/kvaser_usb/kvaser_usb.h | 2 ++
> drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c | 2 +-
> drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c | 6 ++++++
> 3 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/can/usb/kvaser_usb/kvaser_usb.h b/drivers/net/can/usb/kvaser_usb/kvaser_usb.h
> index 3a49257f9fa6..f1bea13a3829 100644
> --- a/drivers/net/can/usb/kvaser_usb/kvaser_usb.h
> +++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb.h
> @@ -175,6 +175,8 @@ struct kvaser_usb_dev_cfg {
> extern const struct kvaser_usb_dev_ops kvaser_usb_hydra_dev_ops;
> extern const struct kvaser_usb_dev_ops kvaser_usb_leaf_dev_ops;
>
> +void kvaser_usb_unlink_tx_urbs(struct kvaser_usb_net_priv *priv);
> +
> int kvaser_usb_recv_cmd(const struct kvaser_usb *dev, void *cmd, int len,
> int *actual_len);
>
> diff --git a/drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c b/drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c
> index 7388fdca9079..a8d72fb8291a 100644
> --- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c
> +++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c
> @@ -440,7 +440,7 @@ static void kvaser_usb_reset_tx_urb_contexts(struct kvaser_usb_net_priv *priv)
> /* This method might sleep. Do not call it in the atomic context
> * of URB completions.
> */
> -static void kvaser_usb_unlink_tx_urbs(struct kvaser_usb_net_priv *priv)
> +void kvaser_usb_unlink_tx_urbs(struct kvaser_usb_net_priv *priv)
> {
> usb_kill_anchored_urbs(&priv->tx_submitted);
> kvaser_usb_reset_tx_urb_contexts(priv);
> 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 d7f2d64a8083..2d30a662edb5 100644
> --- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
> +++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
> @@ -1402,6 +1402,12 @@ static int kvaser_usb_leaf_set_mode(struct net_device *netdev,
>
> switch (mode) {
> case CAN_MODE_START:
> + err = kvaser_usb_leaf_flush_queue(priv);

All affected devices, leaf and usbcanII, will flush the Tx queue when
receiving CMD_START_CHIP.
So this is superfluous, and can be removed.

> + if (err)
> + return err;
> +
> + kvaser_usb_unlink_tx_urbs(priv);
> +
> err = kvaser_usb_leaf_simple_cmd_async(priv, CMD_START_CHIP);
> if (err)
> return err;

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