linux-kernel - Re: [PATCH v3 ] remoteproc: Use unbounded workqueue for recovery work

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Date:   Tue, 12 Apr 2022 19:25:50 +0530
From:   Mukesh Ojha <quic_mojha@...cinc.com>
To:     <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <bjorn.andersson@...aro.org>, <mathieu.poirier@...aro.org>
Subject: Re: [PATCH v3 ] remoteproc: Use unbounded workqueue for recovery work

Hi,

Can we consider this ? please suggest.

Thanks,
-Mukesh

On 4/11/2022 10:00 PM, Mukesh Ojha wrote:
> There could be a scenario where there is too much load on a core
> (n number of tasks which is affined) or in a case when multiple
> rproc subsystem is going for a recovery and they queued recovery
> work to one core so even though subsystem are independent there
> recovery will be delayed if one of the subsystem recovery work
> is taking more time in completing.
>
> If we make this queue unbounded, the recovery work could be picked
> on any cpu. This patch try to address this.
>
> Signed-off-by: Mukesh Ojha <quic_mojha@...cinc.com>
> ---
> Changes in v3:
>    - Add fallback option to go back to earlier path incase recovery wq
>      creation fails.
>
> Changes in v2:
>    - Removed WQ_HIGHPRI.
>    - Updated commit text.
>
>   drivers/remoteproc/remoteproc_core.c | 15 +++++++++++++--
>   1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index c510125..6446c84 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -59,6 +59,7 @@ static int rproc_release_carveout(struct rproc *rproc,
>   
>   /* Unique indices for remoteproc devices */
>   static DEFINE_IDA(rproc_dev_index);
> +static struct workqueue_struct *rproc_recovery_wq;
>   
>   static const char * const rproc_crash_names[] = {
>   	[RPROC_MMUFAULT]	= "mmufault",
> @@ -2755,8 +2756,11 @@ void rproc_report_crash(struct rproc *rproc, enum rproc_crash_type type)
>   	dev_err(&rproc->dev, "crash detected in %s: type %s\n",
>   		rproc->name, rproc_crash_to_string(type));
>   
> -	/* Have a worker handle the error; ensure system is not suspended */
> -	queue_work(system_freezable_wq, &rproc->crash_handler);
> +	if (rproc_recovery_wq)
> +		queue_work(rproc_recovery_wq, &rproc->crash_handler);
> +	else
> +		queue_work(system_freezable_wq, &rproc->crash_handler);
> +
>   }
>   EXPORT_SYMBOL(rproc_report_crash);
>   
> @@ -2805,6 +2809,11 @@ static void __exit rproc_exit_panic(void)
>   
>   static int __init remoteproc_init(void)
>   {
> +	rproc_recovery_wq = alloc_workqueue("rproc_recovery_wq",
> +						WQ_UNBOUND | WQ_FREEZABLE, 0);
> +	if (!rproc_recovery_wq)
> +		pr_err("remoteproc: creation of rproc_recovery_wq failed\n");
> +
>   	rproc_init_sysfs();
>   	rproc_init_debugfs();
>   	rproc_init_cdev();
> @@ -2821,6 +2830,8 @@ static void __exit remoteproc_exit(void)
>   	rproc_exit_panic();
>   	rproc_exit_debugfs();
>   	rproc_exit_sysfs();
> +	if (rproc_recovery_wq)
> +		destroy_workqueue(rproc_recovery_wq);
>   }
>   module_exit(remoteproc_exit);
>