Commit 33654ef4 authored by Christian König's avatar Christian König Committed by Thomas Hellström
Browse files

drm/i915: remove questionable fence optimization during copy 



First of all as discussed multiple times now kernel copies *must* always
wait for all fences in a BO before actually doing the copy. This is
mandatory.

Additional to that drop the handling when there can't be a shared slot
allocated on the source BO and just properly return an error code.
Otherwise this code path would only be tested under out of memory
conditions.

Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
Reviewed-by: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211221200050.436316-3-thomas.hellstrom@linux.intel.com


Signed-off-by: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
parent 11930817

drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c

+14 −29
Original line number Diff line number Diff line
@@ -195,19 +195,14 @@ static int i915_deps_add_dependency(struct i915_deps *deps, 
}



static int i915_deps_add_resv(struct i915_deps *deps, struct dma_resv *resv,

			      bool all, const bool no_excl,

			      const struct ttm_operation_ctx *ctx)

{

	struct dma_resv_iter iter;

	struct dma_fence *fence;



	dma_resv_assert_held(resv);

	dma_resv_for_each_fence(&iter, resv, all, fence) {

	int ret;



		if (no_excl && dma_resv_iter_is_exclusive(&iter))

			continue;



	dma_resv_assert_held(resv);

	dma_resv_for_each_fence(&iter, resv, true, fence) {

		ret = i915_deps_add_dependency(deps, fence, ctx);

		if (ret)

			return ret;
@@ -634,11 +629,7 @@ prev_deps(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx, 


	ret = i915_deps_add_dependency(deps, bo->moving, ctx);

	if (!ret)

		/*

		 * TODO: Only await excl fence here, and shared fences before

		 * signaling the migration fence.

		 */

		ret = i915_deps_add_resv(deps, bo->base.resv, true, false, ctx);

		ret = i915_deps_add_resv(deps, bo->base.resv, ctx);



	return ret;

}
@@ -768,22 +759,21 @@ int i915_gem_obj_copy_ttm(struct drm_i915_gem_object *dst, 
	struct i915_refct_sgt *dst_rsgt;

	struct dma_fence *copy_fence;

	struct i915_deps deps;

	int ret, shared_err;

	int ret;



	assert_object_held(dst);

	assert_object_held(src);

	i915_deps_init(&deps, GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);



	/*

	 * We plan to add a shared fence only for the source. If that

	 * fails, we await all source fences before commencing

	 * the copy instead of only the exclusive.

	 */

	shared_err = dma_resv_reserve_shared(src_bo->base.resv, 1);

	ret = i915_deps_add_resv(&deps, dst_bo->base.resv, true, false, &ctx);

	if (!ret)

		ret = i915_deps_add_resv(&deps, src_bo->base.resv,

					 !!shared_err, false, &ctx);

	ret = dma_resv_reserve_shared(src_bo->base.resv, 1);

	if (ret)

		return ret;



	ret = i915_deps_add_resv(&deps, dst_bo->base.resv, &ctx);

	if (ret)

		return ret;



	ret = i915_deps_add_resv(&deps, src_bo->base.resv, &ctx);

	if (ret)

		return ret;
@@ -798,11 +788,6 @@ int i915_gem_obj_copy_ttm(struct drm_i915_gem_object *dst, 
		return PTR_ERR_OR_ZERO(copy_fence);



	dma_resv_add_excl_fence(dst_bo->base.resv, copy_fence);



	/* If we failed to reserve a shared slot, add an exclusive fence */

	if (shared_err)

		dma_resv_add_excl_fence(src_bo->base.resv, copy_fence);

	else

	dma_resv_add_shared_fence(src_bo->base.resv, copy_fence);



	dma_fence_put(copy_fence);