linux-kernel - Re: [PATCH] drm/panfrost:modify 'break' to 'continue' to traverse the circulation

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Date:   Fri, 18 Jun 2021 13:43:25 +0100
From:   Steven Price <steven.price@....com>
To:     ChunyouTang <tangchunyou@....com>, robh@...nel.org,
        tomeu.vizoso@...labora.com, alyssa.rosenzweig@...labora.com,
        airlied@...ux.ie, daniel@...ll.ch
Cc:     ChunyouTang <tangchunyou@...becorp.cn>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] drm/panfrost:modify 'break' to 'continue' to traverse the
 circulation

On 17/06/2021 09:04, ChunyouTang wrote:
> From: ChunyouTang <tangchunyou@...becorp.cn>
> 
> The 'break' can cause 'Memory manager not clean during takedown'
> 
> It cannot use break to finish the circulation,it should use
> 
> continue to traverse the circulation.it should put every mapping
> 
> which is not NULL.

You don't appear to have answered my question about whether you've
actually seen this happen (and ideally what circumstances). In my
previous email[1] I explained why I don't think this is needed. You need
to convince me that I've overlooked something.

Thanks,

Steve

[1] https://lore.kernel.org/r/31644881-134a-2d6e-dddf-e658a3a8176b%40arm.com

> Signed-off-by: ChunyouTang <tangchunyou@...becorp.cn>
> ---
>  drivers/gpu/drm/panfrost/panfrost_job.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
> index 6003cfeb1322..52bccc1d2d42 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_job.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
> @@ -281,7 +281,7 @@ static void panfrost_job_cleanup(struct kref *ref)
>  	if (job->mappings) {
>  		for (i = 0; i < job->bo_count; i++) {
>  			if (!job->mappings[i])
> -				break;
> +				continue;
>  
>  			atomic_dec(&job->mappings[i]->obj->gpu_usecount);
>  			panfrost_gem_mapping_put(job->mappings[i]);
>