Re: [PATCH v4 ] remoteproc: Use unbounded workqueue for recovery work

[Mukesh Ojha <quic_mojha@quicinc.com>]

Hi Bjorn/Mathieu,

Could you please review this ?

-Mukesh

On 4/19/2022 4:55 PM, Mukesh Ojha wrote:
> There could be a scenario when 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 recovery, they queue their recovery
> work to one core so even though subsystem are independent their
> 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 is trying to address this.
> 
> Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
> ---
> Changes in v4:
>    - Removed fallback option on @sarvana comment
>    - Fail the init on workqueue creation failure.
>    - modified commit text.
> 
> 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..c8a1e3e 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 +2756,7 @@ 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);
> +	queue_work(rproc_recovery_wq, &rproc->crash_handler);
>   }
>   EXPORT_SYMBOL(rproc_report_crash);
>   
> @@ -2805,6 +2805,13 @@ 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");
> +		return -ENOMEM;
> +	}
> +
>   	rproc_init_sysfs();
>   	rproc_init_debugfs();
>   	rproc_init_cdev();
> @@ -2818,9 +2825,13 @@ static void __exit remoteproc_exit(void)
>   {
>   	ida_destroy(&rproc_dev_index);
>   
> +	if (!rproc_recovery_wq)
> +		return;
> +
>   	rproc_exit_panic();
>   	rproc_exit_debugfs();
>   	rproc_exit_sysfs();
> +	destroy_workqueue(rproc_recovery_wq);
>   }
>   module_exit(remoteproc_exit);
>