linux-kernel - Re: [PATCH v1] drm/msm: Move fence put to where failure occurs

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Message-ID: <154108957570.30246.16686926988338640470@skylake-alporthouse-com>
Date:   Thu, 01 Nov 2018 16:26:15 +0000
From:   Chris Wilson <chris@...is-wilson.co.uk>
To:     Robert Foss <robert.foss@...labora.com>, airlied@...ux.ie,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        robdclark@...il.com
Cc:     Robert Foss <robert.foss@...labora.com>
Subject: Re: [PATCH v1] drm/msm: Move fence put to where failure occurs

Quoting Robert Foss (2018-11-01 16:12:28)
> If dma_fence_wait fails to wait for a supplied in-fence in
> msm_ioctl_gem_submit, make sure we release that in-fence.
> 
> Also remove this dma_fence_put() from the 'out' label.
> 
> Signed-off-by: Robert Foss <robert.foss@...labora.com>
> ---
>  drivers/gpu/drm/msm/msm_gem_submit.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
> index a90aedd6883a..3e7704af5b24 100644
> --- a/drivers/gpu/drm/msm/msm_gem_submit.c
> +++ b/drivers/gpu/drm/msm/msm_gem_submit.c
> @@ -411,7 +411,6 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
>         struct msm_file_private *ctx = file->driver_priv;
>         struct msm_gem_submit *submit;
>         struct msm_gpu *gpu = priv->gpu;
> -       struct dma_fence *in_fence = NULL;
>         struct sync_file *sync_file = NULL;
>         struct msm_gpu_submitqueue *queue;
>         struct msm_ringbuffer *ring;
> @@ -444,7 +443,8 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
>         ring = gpu->rb[queue->prio];
>  
>         if (args->flags & MSM_SUBMIT_FENCE_FD_IN) {
> -               in_fence = sync_file_get_fence(args->fence_fd);
> +               struct dma_fence *in_fence = sync_file_get_fence(
> +                       args->fence_fd);
>  
>                 if (!in_fence)
>                         return -EINVAL;
> @@ -455,8 +455,10 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
>                  */
>                 if (!dma_fence_match_context(in_fence, ring->fctx->context)) {
>                         ret = dma_fence_wait(in_fence, true);
> -                       if (ret)
> +                       if (ret) {
> +                               dma_fence_put(in_fence);
>                                 return ret;
> +                       }
>                 }

Careful, we need to keep the put for the normal path. Maybe,

if (args->flags & MSM_SUBMIT_FENCE_FD_IN) {
	struct dma_fence *in_fence;

	in_fence = sync_file_get_fence(args->fence_fd); // keep line breaks natural
	if (!in_fence)
		return -EINVAL;
	
	ret = 0;
	if (!dma_fence_match_match_context(in_fence, ring->fctx->context)
		ret = dma_fence_wait(in_fence, true);
	dma_fence_put(in_fence);
	if (ret)
		return ret;
}