[PATCH 04/11] drm/syncobj: use only a single stub fence

[zhoucm1]

Could you move this one to dma-fence as you said? Which will be used in 
other place as well.

-David


On 2018年11月28日 22:50, Christian König wrote:
> Extract of useful code from the timeline work. Let's use just a single
> stub fence instance instead of allocating a new one all the time.
>
> Signed-off-by: Chunming Zhou <david1.zhou at amd.com>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>   drivers/gpu/drm/drm_syncobj.c | 67 ++++++++++++++++++++++---------------------
>   1 file changed, 35 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
> index b92e3c726229..f78321338c1f 100644
> --- a/drivers/gpu/drm/drm_syncobj.c
> +++ b/drivers/gpu/drm/drm_syncobj.c
> @@ -56,10 +56,8 @@
>   #include "drm_internal.h"
>   #include <drm/drm_syncobj.h>
>   
> -struct drm_syncobj_stub_fence {
> -	struct dma_fence base;
> -	spinlock_t lock;
> -};
> +static DEFINE_SPINLOCK(stub_fence_lock);
> +static struct dma_fence stub_fence;
>   
>   static const char *drm_syncobj_stub_fence_get_name(struct dma_fence *fence)
>   {
> @@ -71,6 +69,25 @@ static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
>   	.get_timeline_name = drm_syncobj_stub_fence_get_name,
>   };
>   
> +/**
> + * drm_syncobj_get_stub_fence - return a signaled fence
> + *
> + * Return a stub fence which is already signaled.
> + */
> +static struct dma_fence *drm_syncobj_get_stub_fence(void)
> +{
> +	spin_lock(&stub_fence_lock);
> +	if (!stub_fence.ops) {
> +		dma_fence_init(&stub_fence,
> +			       &drm_syncobj_stub_fence_ops,
> +			       &stub_fence_lock,
> +			       0, 0);
> +		dma_fence_signal_locked(&stub_fence);
> +	}
> +	spin_unlock(&stub_fence_lock);
> +
> +	return dma_fence_get(&stub_fence);
> +}
>   
>   /**
>    * drm_syncobj_find - lookup and reference a sync object.
> @@ -188,23 +205,18 @@ void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
>   }
>   EXPORT_SYMBOL(drm_syncobj_replace_fence);
>   
> -static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
> +/**
> + * drm_syncobj_assign_null_handle - assign a stub fence to the sync object
> + * @syncobj: sync object to assign the fence on
> + *
> + * Assign a already signaled stub fence to the sync object.
> + */
> +static void drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
>   {
> -	struct drm_syncobj_stub_fence *fence;
> -	fence = kzalloc(sizeof(*fence), GFP_KERNEL);
> -	if (fence == NULL)
> -		return -ENOMEM;
> +	struct dma_fence *fence = drm_syncobj_get_stub_fence();
>   
> -	spin_lock_init(&fence->lock);
> -	dma_fence_init(&fence->base, &drm_syncobj_stub_fence_ops,
> -		       &fence->lock, 0, 0);
> -	dma_fence_signal(&fence->base);
> -
> -	drm_syncobj_replace_fence(syncobj, &fence->base);
> -
> -	dma_fence_put(&fence->base);
> -
> -	return 0;
> +	drm_syncobj_replace_fence(syncobj, fence);
> +	dma_fence_put(fence);
>   }
>   
>   /**
> @@ -272,7 +284,6 @@ EXPORT_SYMBOL(drm_syncobj_free);
>   int drm_syncobj_create(struct drm_syncobj **out_syncobj, uint32_t flags,
>   		       struct dma_fence *fence)
>   {
> -	int ret;
>   	struct drm_syncobj *syncobj;
>   
>   	syncobj = kzalloc(sizeof(struct drm_syncobj), GFP_KERNEL);
> @@ -283,13 +294,8 @@ int drm_syncobj_create(struct drm_syncobj **out_syncobj, uint32_t flags,
>   	INIT_LIST_HEAD(&syncobj->cb_list);
>   	spin_lock_init(&syncobj->lock);
>   
> -	if (flags & DRM_SYNCOBJ_CREATE_SIGNALED) {
> -		ret = drm_syncobj_assign_null_handle(syncobj);
> -		if (ret < 0) {
> -			drm_syncobj_put(syncobj);
> -			return ret;
> -		}
> -	}
> +	if (flags & DRM_SYNCOBJ_CREATE_SIGNALED)
> +		drm_syncobj_assign_null_handle(syncobj);
>   
>   	if (fence)
>   		drm_syncobj_replace_fence(syncobj, fence);
> @@ -980,11 +986,8 @@ drm_syncobj_signal_ioctl(struct drm_device *dev, void *data,
>   	if (ret < 0)
>   		return ret;
>   
> -	for (i = 0; i < args->count_handles; i++) {
> -		ret = drm_syncobj_assign_null_handle(syncobjs[i]);
> -		if (ret < 0)
> -			break;
> -	}
> +	for (i = 0; i < args->count_handles; i++)
> +		drm_syncobj_assign_null_handle(syncobjs[i]);
>   
>   	drm_syncobj_array_free(syncobjs, args->count_handles);
>