From 33654ef470a97f9fcb19abc7e7ef660ea37e3aed Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Christian=20K=C3=B6nig?= Date: Tue, 21 Dec 2021 21:00:48 +0100 Subject: [PATCH] drm/i915: remove questionable fence optimization during copy MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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: Christian König Reviewed-by: Thomas Hellström Link: https://patchwork.freedesktop.org/patch/msgid/20211221200050.436316-3-thomas.hellstrom@linux.intel.com Signed-off-by: Thomas Hellström --- drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c | 43 +++++++------------- 1 file changed, 14 insertions(+), 29 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c index 62a6fd2d127d..5dbaccf3f201 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c @@ -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; + int ret; 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_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; @@ -798,12 +788,7 @@ 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_resv_add_shared_fence(src_bo->base.resv, copy_fence); dma_fence_put(copy_fence);