linux-kernel - Re: [PATCH 1/2] rpmsg: glink: change rx work queue type

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Date:   Tue, 11 Jul 2023 17:50:36 +0530
From:   Manikanta Mylavarapu <quic_mmanikan@...cinc.com>
To:     <agross@...nel.org>, <andersson@...nel.org>,
        <konrad.dybcio@...aro.org>, <mathieu.poirier@...aro.org>,
        <linux-arm-msm@...r.kernel.org>,
        <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <quic_srichara@...cinc.com>, <quic_sjaganat@...cinc.com>,
        <quic_kathirav@...cinc.com>, <quic_anusha@...cinc.com>,
        <quic_varada@...cinc.com>
Subject: Re: [PATCH 1/2] rpmsg: glink: change rx work queue type



On 6/7/2023 5:47 PM, Manikanta Mylavarapu wrote:
> In case of heavy cpu load, rx worker thread
> not able to get cpu slot because it's bound
> to kernel global work queue.
> 
> Glink client drivers will return timeout
> error if they didn't receive response
> within stipulated duration. Changing rx
> work queue type to UNBOUND workqueue
> ensures rx worker thread will be executed
> as early as possible.
> 
> Signed-off-by: Manikanta Mylavarapu <quic_mmanikan@...cinc.com>
> ---
>   drivers/rpmsg/qcom_glink_native.c | 10 +++++++++-
>   1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> index 1beb40a1d3df..6f9a439e5046 100644
> --- a/drivers/rpmsg/qcom_glink_native.c
> +++ b/drivers/rpmsg/qcom_glink_native.c
> @@ -81,6 +81,7 @@ struct glink_core_rx_intent {
>    * @rx_pipe:	pipe object for receive FIFO
>    * @tx_pipe:	pipe object for transmit FIFO
>    * @rx_work:	worker for handling received control messages
> + * @rx_wq:	work queue of rx_work
>    * @rx_lock:	protects the @rx_queue
>    * @rx_queue:	queue of received control messages to be processed in @rx_work
>    * @tx_lock:	synchronizes operations on the tx fifo
> @@ -100,6 +101,7 @@ struct qcom_glink {
>   	struct qcom_glink_pipe *tx_pipe;
>   
>   	struct work_struct rx_work;
> +	struct workqueue_struct *rx_wq;
>   	spinlock_t rx_lock;
>   	struct list_head rx_queue;
>   
> @@ -822,7 +824,7 @@ static int qcom_glink_rx_defer(struct qcom_glink *glink, size_t extra)
>   	list_add_tail(&dcmd->node, &glink->rx_queue);
>   	spin_unlock(&glink->rx_lock);
>   
> -	schedule_work(&glink->rx_work);
> +	queue_work(glink->rx_wq, &glink->rx_work);
>   	qcom_glink_rx_advance(glink, sizeof(dcmd->msg) + extra);
>   
>   	return 0;
> @@ -1665,6 +1667,8 @@ static void qcom_glink_cancel_rx_work(struct qcom_glink *glink)
>   	/* cancel any pending deferred rx_work */
>   	cancel_work_sync(&glink->rx_work);
>   
> +	destroy_workqueue(glink->rx_wq);
> +
>   	list_for_each_entry_safe(dcmd, tmp, &glink->rx_queue, node)
>   		kfree(dcmd);
>   }
> @@ -1750,6 +1754,10 @@ struct qcom_glink *qcom_glink_native_probe(struct device *dev,
>   	INIT_WORK(&glink->rx_work, qcom_glink_work);
>   	init_waitqueue_head(&glink->tx_avail_notify);
>   
> +	glink->rx_wq = alloc_workqueue("glink_rx_wq", WQ_UNBOUND, 1);
> +	if (!glink->rx_wq)
> +		return ERR_PTR(-ENOMEM);
> +
>   	spin_lock_init(&glink->idr_lock);
>   	idr_init(&glink->lcids);
>   	idr_init(&glink->rcids);


Gentle reminder for review!

Thanks,
Manikanta.