Message-ID: <25bd9a77-a703-6eb6-e142-5da9e54754a0@amd.com>
Date:   Mon, 20 Mar 2023 17:52:16 +0100
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Subject: Re: [PATCH v2 01/23] drm/msm: Pre-allocate hw_fence
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To:     Rob Clark <robdclark@gmail.com>, dri-devel@lists.freedesktop.org
Cc:     Daniel Vetter <daniel@ffwll.ch>, freedreno@lists.freedesktop.org,
        linux-arm-msm@vger.kernel.org, Rob Clark <robdclark@chromium.org>,
        Abhinav Kumar <quic_abhinavk@quicinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
        Sean Paul <sean@poorly.run>, David Airlie <airlied@gmail.com>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:DMA BUFFER SHARING FRAMEWORK" 
        <linux-media@vger.kernel.org>,
        "moderated list:DMA BUFFER SHARING FRAMEWORK" 
        <linaro-mm-sig@lists.linaro.org>
References: <20230320144356.803762-1-robdclark@gmail.com>
 <20230320144356.803762-2-robdclark@gmail.com>
From:   =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>
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Am 20.03.23 um 15:43 schrieb Rob Clark:
> From: Rob Clark <robdclark@chromium.org>
>
> Avoid allocating memory in job_run() by pre-allocating the hw_fence.
>
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
>   drivers/gpu/drm/msm/msm_fence.c      | 12 +++++++++---
>   drivers/gpu/drm/msm/msm_fence.h      |  3 ++-
>   drivers/gpu/drm/msm/msm_gem_submit.c |  7 +++++++
>   drivers/gpu/drm/msm/msm_ringbuffer.c |  2 +-
>   4 files changed, 19 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/msm_fence.c b/drivers/gpu/drm/msm/msm_fence.c
> index 56641408ea74..bab3d84f1686 100644
> --- a/drivers/gpu/drm/msm/msm_fence.c
> +++ b/drivers/gpu/drm/msm/msm_fence.c
> @@ -99,7 +99,7 @@ static const struct dma_fence_ops msm_fence_ops = {
>   };
>   
>   struct dma_fence *
> -msm_fence_alloc(struct msm_fence_context *fctx)
> +msm_fence_alloc(void)
>   {
>   	struct msm_fence *f;
>   
> @@ -107,10 +107,16 @@ msm_fence_alloc(struct msm_fence_context *fctx)
>   	if (!f)
>   		return ERR_PTR(-ENOMEM);
>   
> +	return &f->base;
> +}
> +
> +void
> +msm_fence_init(struct dma_fence *fence, struct msm_fence_context *fctx)
> +{
> +	struct msm_fence *f = to_msm_fence(fence);
> +
>   	f->fctx = fctx;
>   
>   	dma_fence_init(&f->base, &msm_fence_ops, &fctx->spinlock,
>   		       fctx->context, ++fctx->last_fence);
> -
> -	return &f->base;
>   }
> diff --git a/drivers/gpu/drm/msm/msm_fence.h b/drivers/gpu/drm/msm/msm_fence.h
> index 7f1798c54cd1..f913fa22d8fe 100644
> --- a/drivers/gpu/drm/msm/msm_fence.h
> +++ b/drivers/gpu/drm/msm/msm_fence.h
> @@ -61,7 +61,8 @@ void msm_fence_context_free(struct msm_fence_context *fctx);
>   bool msm_fence_completed(struct msm_fence_context *fctx, uint32_t fence);
>   void msm_update_fence(struct msm_fence_context *fctx, uint32_t fence);
>   
> -struct dma_fence * msm_fence_alloc(struct msm_fence_context *fctx);
> +struct dma_fence * msm_fence_alloc(void);
> +void msm_fence_init(struct dma_fence *fence, struct msm_fence_context *fctx);
>   
>   static inline bool
>   fence_before(uint32_t a, uint32_t b)
> diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
> index be4bf77103cd..2570c018b0cb 100644
> --- a/drivers/gpu/drm/msm/msm_gem_submit.c
> +++ b/drivers/gpu/drm/msm/msm_gem_submit.c
> @@ -41,6 +41,13 @@ static struct msm_gem_submit *submit_create(struct drm_device *dev,
>   	if (!submit)
>   		return ERR_PTR(-ENOMEM);
>   
> +	submit->hw_fence = msm_fence_alloc();
> +	if (IS_ERR(submit->hw_fence)) {
> +		ret = PTR_ERR(submit->hw_fence);
> +		kfree(submit);
> +		return ERR_PTR(ret);
> +	}
> +
>   	ret = drm_sched_job_init(&submit->base, queue->entity, queue);
>   	if (ret) {
>   		kfree(submit);

You probably need some error handling here or otherwise leak 
submit->hw_fence.

Apart from that looks good to me.

Christian.

> diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.c b/drivers/gpu/drm/msm/msm_ringbuffer.c
> index 57a8e9564540..a62b45e5a8c3 100644
> --- a/drivers/gpu/drm/msm/msm_ringbuffer.c
> +++ b/drivers/gpu/drm/msm/msm_ringbuffer.c
> @@ -18,7 +18,7 @@ static struct dma_fence *msm_job_run(struct drm_sched_job *job)
>   	struct msm_gpu *gpu = submit->gpu;
>   	int i;
>   
> -	submit->hw_fence = msm_fence_alloc(fctx);
> +	msm_fence_init(submit->hw_fence, fctx);
>   
>   	for (i = 0; i < submit->nr_bos; i++) {
>   		struct drm_gem_object *obj = &submit->bos[i].obj->base;