Re: [PATCH 5/6] rpmsg: glink: Fail qcom_glink_tx() once remove has been initiated

[Chris Lew <quic_clew@xxxxxxxxxxx>]

On 1/9/2023 2:40 PM, Bjorn Andersson wrote:
> Upon removing the glink edge communication is at best one-way. This

glink edge, communication

> means that the very common scenario of glink requesting intents will not
> be possible to serve.
>
> Typically a successful transmission results in the client waiting for a
> response, with some timeout and a mechanism for aborting that timeout.
>
> Because of this, once the glink edge is defunct once removal is
> commenced it's better to fail transmissions fast.
>
> Signed-off-by: Bjorn Andersson <quic_bjorande@xxxxxxxxxxx>
> ---

Reviewed-by: Chris Lew <quic_clew@xxxxxxxxxxx>

>   drivers/rpmsg/qcom_glink_native.c | 20 ++++++++++++++++++++
>   1 file changed, 20 insertions(+)
>
> diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> index db5d946d5901..d81d0729493e 100644
> --- a/drivers/rpmsg/qcom_glink_native.c
> +++ b/drivers/rpmsg/qcom_glink_native.c
> @@ -90,6 +90,7 @@ struct glink_core_rx_intent {
>    * @intentless:	flag to indicate that there is no intent
>    * @tx_avail_notify: Waitqueue for pending tx tasks
>    * @sent_read_notify: flag to check cmd sent or not
> + * @abort_tx:	flag indicating that all tx attempts should fail
>    */
>   struct qcom_glink {
>   	struct device *dev;
> @@ -111,6 +112,8 @@ struct qcom_glink {
>   	bool intentless;
>   	wait_queue_head_t tx_avail_notify;
>   	bool sent_read_notify;
> +
> +	bool abort_tx;
>   };
>   
>   enum {
> @@ -326,12 +329,22 @@ static int qcom_glink_tx(struct qcom_glink *glink,
>   
>   	spin_lock_irqsave(&glink->tx_lock, flags);
>   
> +	if (glink->abort_tx) {
> +		ret = -EIO;
> +		goto out;
> +	}
> +
>   	while (qcom_glink_tx_avail(glink) < tlen) {
>   		if (!wait) {
>   			ret = -EAGAIN;
>   			goto out;
>   		}
>   
> +		if (glink->abort_tx) {
> +			ret = -EIO;
> +			goto out;
> +		}
> +
>   		if (!glink->sent_read_notify) {
>   			glink->sent_read_notify = true;
>   			qcom_glink_send_read_notify(glink);
> @@ -1763,11 +1776,18 @@ static int qcom_glink_remove_device(struct device *dev, void *data)
>   void qcom_glink_native_remove(struct qcom_glink *glink)
>   {
>   	struct glink_channel *channel;
> +	unsigned long flags;
>   	int cid;
>   	int ret;
>   
>   	qcom_glink_cancel_rx_work(glink);
>   
> +	/* Fail all attempts at sending messages */
> +	spin_lock_irqsave(&glink->tx_lock, flags);
> +	glink->abort_tx = true;
> +	wake_up_all(&glink->tx_avail_notify);
> +	spin_unlock_irqrestore(&glink->tx_lock, flags);
> +
>   	ret = device_for_each_child(glink->dev, NULL, qcom_glink_remove_device);
>   	if (ret)
>   		dev_warn(glink->dev, "Can't remove GLINK devices: %d\n", ret);