dma-buf: specify usage while adding fences to dma_resv obj v7

Instead of distingting between shared and exclusive fences specify
the fence usage while adding fences.

Rework all drivers to use this interface instead and deprecate the old one.

v2: some kerneldoc comments suggested by Daniel
v3: fix a missing case in radeon
v4: rebase on nouveau changes, fix lockdep and temporary disable warning
v5: more documentation updates
v6: separate internal dma_resv changes from this patch, avoids to
disable warning temporary, rebase on upstream changes
v7: fix missed case in lima driver, minimize changes to i915_gem_busy_ioctl

Signed-off-by: Christian König <[e-mail]>
Reviewed-by: Daniel Vetter <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/dma-buf/dma-resv.c

···
 
 #ifdef CONFIG_DEBUG_MUTEXES
 /**
- * dma_resv_reset_shared_max - reset shared fences for debugging
+ * dma_resv_reset_max_fences - reset shared fences for debugging
  * @obj: the dma_resv object to reset
  *
  * Reset the number of pre-reserved shared slots to test that drivers do
  * correct slot allocation using dma_resv_reserve_fences(). See also
  * &dma_resv_list.shared_max.
  */
-void dma_resv_reset_shared_max(struct dma_resv *obj)
+void dma_resv_reset_max_fences(struct dma_resv *obj)
 {
 	struct dma_resv_list *fences = dma_resv_shared_list(obj);
 
···
 	if (fences)
 		fences->shared_max = fences->shared_count;
 }
-EXPORT_SYMBOL(dma_resv_reset_shared_max);
+EXPORT_SYMBOL(dma_resv_reset_max_fences);
 #endif
 
 /**
···
  *
  * See also &dma_resv.fence for a discussion of the semantics.
  */
-void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence)
+static void dma_resv_add_shared_fence(struct dma_resv *obj,
+				      struct dma_fence *fence)
 {
 	struct dma_resv_list *fobj;
 	struct dma_fence *old;
···
 	write_seqcount_end(&obj->seq);
 	dma_fence_put(old);
 }
-EXPORT_SYMBOL(dma_resv_add_shared_fence);
 
 /**
  * dma_resv_replace_fences - replace fences in the dma_resv obj
  * @obj: the reservation object
  * @context: the context of the fences to replace
  * @replacement: the new fence to use instead
+ * @usage: how the new fence is used, see enum dma_resv_usage
  *
  * Replace fences with a specified context with a new fence. Only valid if the
  * operation represented by the original fence has no longer access to the
···
  * update fence which makes the resource inaccessible.
  */
 void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
-			     struct dma_fence *replacement)
+			     struct dma_fence *replacement,
+			     enum dma_resv_usage usage)
 {
 	struct dma_resv_list *list;
 	struct dma_fence *old;
 	unsigned int i;
+
+	/* Only readers supported for now */
+	WARN_ON(usage != DMA_RESV_USAGE_READ);
 
 	dma_resv_assert_held(obj);
 
···
  * Add a fence to the exclusive slot. @obj must be locked with dma_resv_lock().
  * See also &dma_resv.fence_excl for a discussion of the semantics.
  */
-void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
+static void dma_resv_add_excl_fence(struct dma_resv *obj,
+				    struct dma_fence *fence)
 {
 	struct dma_fence *old_fence = dma_resv_excl_fence(obj);
 
···
 
 	dma_fence_put(old_fence);
 }
-EXPORT_SYMBOL(dma_resv_add_excl_fence);
+
+/**
+ * dma_resv_add_fence - Add a fence to the dma_resv obj
+ * @obj: the reservation object
+ * @fence: the fence to add
+ * @usage: how the fence is used, see enum dma_resv_usage
+ *
+ * Add a fence to a slot, @obj must be locked with dma_resv_lock(), and
+ * dma_resv_reserve_fences() has been called.
+ *
+ * See also &dma_resv.fence for a discussion of the semantics.
+ */
+void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence,
+			enum dma_resv_usage usage)
+{
+	if (usage == DMA_RESV_USAGE_WRITE)
+		dma_resv_add_excl_fence(obj, fence);
+	else
+		dma_resv_add_shared_fence(obj, fence);
+}
+EXPORT_SYMBOL(dma_resv_add_fence);
 
 /* Restart the iterator by initializing all the necessary fields, but not the
  * relation to the dma_resv object. */
···
 		}
 
 		dma_fence_get(f);
-		if (dma_resv_iter_is_exclusive(&cursor))
+		if (dma_resv_iter_usage(&cursor) == DMA_RESV_USAGE_WRITE)
 			excl = f;
 		else
 			RCU_INIT_POINTER(list->shared[list->shared_count++], f);
···
  */
 void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq)
 {
+	static const char *usage[] = { "write", "read" };
 	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
 
 	dma_resv_for_each_fence(&cursor, obj, DMA_RESV_USAGE_READ, fence) {
 		seq_printf(seq, "\t%s fence:",
-			   dma_resv_iter_is_exclusive(&cursor) ?
-				"Exclusive" : "Shared");
+			   usage[dma_resv_iter_usage(&cursor)]);
 		dma_fence_describe(fence, seq);
 	}
 }

drivers/dma-buf/st-dma-resv.c

···
 	return r;
 }
 
-static int test_signaling(void *arg, enum dma_resv_usage usage)
+static int test_signaling(void *arg)
 {
+	enum dma_resv_usage usage = (unsigned long)arg;
 	struct dma_resv resv;
 	struct dma_fence *f;
 	int r;
···
 		goto err_unlock;
 	}
 
-	if (usage >= DMA_RESV_USAGE_READ)
-		dma_resv_add_shared_fence(&resv, f);
-	else
-		dma_resv_add_excl_fence(&resv, f);
-
+	dma_resv_add_fence(&resv, f, usage);
 	if (dma_resv_test_signaled(&resv, usage)) {
 		pr_err("Resv unexpectedly signaled\n");
 		r = -EINVAL;
···
 	return r;
 }
 
-static int test_excl_signaling(void *arg)
+static int test_for_each(void *arg)
 {
-	return test_signaling(arg, DMA_RESV_USAGE_WRITE);
-}
-
-static int test_shared_signaling(void *arg)
-{
-	return test_signaling(arg, DMA_RESV_USAGE_READ);
-}
-
-static int test_for_each(void *arg, enum dma_resv_usage usage)
-{
+	enum dma_resv_usage usage = (unsigned long)arg;
 	struct dma_resv_iter cursor;
 	struct dma_fence *f, *fence;
 	struct dma_resv resv;
···
 		goto err_unlock;
 	}
 
-	if (usage >= DMA_RESV_USAGE_READ)
-		dma_resv_add_shared_fence(&resv, f);
-	else
-		dma_resv_add_excl_fence(&resv, f);
+	dma_resv_add_fence(&resv, f, usage);
 
 	r = -ENOENT;
 	dma_resv_for_each_fence(&cursor, &resv, usage, fence) {
···
 			r = -EINVAL;
 			goto err_unlock;
 		}
-		if (dma_resv_iter_is_exclusive(&cursor) !=
-		    (usage >= DMA_RESV_USAGE_READ)) {
+		if (dma_resv_iter_usage(&cursor) != usage) {
 			pr_err("Unexpected fence usage\n");
 			r = -EINVAL;
 			goto err_unlock;
···
 	return r;
 }
 
-static int test_excl_for_each(void *arg)
+static int test_for_each_unlocked(void *arg)
 {
-	return test_for_each(arg, DMA_RESV_USAGE_WRITE);
-}
-
-static int test_shared_for_each(void *arg)
-{
-	return test_for_each(arg, DMA_RESV_USAGE_READ);
-}
-
-static int test_for_each_unlocked(void *arg, enum dma_resv_usage usage)
-{
+	enum dma_resv_usage usage = (unsigned long)arg;
 	struct dma_resv_iter cursor;
 	struct dma_fence *f, *fence;
 	struct dma_resv resv;
···
 		goto err_free;
 	}
 
-	if (usage >= DMA_RESV_USAGE_READ)
-		dma_resv_add_shared_fence(&resv, f);
-	else
-		dma_resv_add_excl_fence(&resv, f);
+	dma_resv_add_fence(&resv, f, usage);
 	dma_resv_unlock(&resv);
 
 	r = -ENOENT;
···
 			r = -EINVAL;
 			goto err_iter_end;
 		}
-		if (dma_resv_iter_is_exclusive(&cursor) !=
-		    (usage >= DMA_RESV_USAGE_READ)) {
+		if (dma_resv_iter_usage(&cursor) != usage) {
 			pr_err("Unexpected fence usage\n");
 			r = -EINVAL;
 			goto err_iter_end;
···
 	return r;
 }
 
-static int test_excl_for_each_unlocked(void *arg)
+static int test_get_fences(void *arg)
 {
-	return test_for_each_unlocked(arg, DMA_RESV_USAGE_WRITE);
-}
-
-static int test_shared_for_each_unlocked(void *arg)
-{
-	return test_for_each_unlocked(arg, DMA_RESV_USAGE_READ);
-}
-
-static int test_get_fences(void *arg, enum dma_resv_usage usage)
-{
+	enum dma_resv_usage usage = (unsigned long)arg;
 	struct dma_fence *f, **fences = NULL;
 	struct dma_resv resv;
 	int r, i;
···
 		goto err_resv;
 	}
 
-	if (usage >= DMA_RESV_USAGE_READ)
-		dma_resv_add_shared_fence(&resv, f);
-	else
-		dma_resv_add_excl_fence(&resv, f);
+	dma_resv_add_fence(&resv, f, usage);
 	dma_resv_unlock(&resv);
 
 	r = dma_resv_get_fences(&resv, usage, &i, &fences);
···
 	return r;
 }
 
-static int test_excl_get_fences(void *arg)
-{
-	return test_get_fences(arg, DMA_RESV_USAGE_WRITE);
-}
-
-static int test_shared_get_fences(void *arg)
-{
-	return test_get_fences(arg, DMA_RESV_USAGE_READ);
-}
-
 int dma_resv(void)
 {
 	static const struct subtest tests[] = {
 		SUBTEST(sanitycheck),
-		SUBTEST(test_excl_signaling),
-		SUBTEST(test_shared_signaling),
-		SUBTEST(test_excl_for_each),
-		SUBTEST(test_shared_for_each),
-		SUBTEST(test_excl_for_each_unlocked),
-		SUBTEST(test_shared_for_each_unlocked),
-		SUBTEST(test_excl_get_fences),
-		SUBTEST(test_shared_get_fences),
+		SUBTEST(test_signaling),
+		SUBTEST(test_for_each),
+		SUBTEST(test_for_each_unlocked),
+		SUBTEST(test_get_fences),
 	};
+	enum dma_resv_usage usage;
+	int r;
 
 	spin_lock_init(&fence_lock);
-	return subtests(tests, NULL);
+	for (usage = DMA_RESV_USAGE_WRITE; usage <= DMA_RESV_USAGE_READ;
+	     ++usage) {
+		r = subtests(tests, (void *)(unsigned long)usage);
+		if (r)
+			return r;
+	}
+	return 0;
 }

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c

···
 	 */
 	replacement = dma_fence_get_stub();
 	dma_resv_replace_fences(bo->tbo.base.resv, ef->base.context,
-				replacement);
+				replacement, DMA_RESV_USAGE_READ);
 	dma_fence_put(replacement);
 	return 0;
 }

drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c

···
 	bo = amdgpu_bo_ref(gem_to_amdgpu_bo(gobj));
 	p->uf_entry.priority = 0;
 	p->uf_entry.tv.bo = &bo->tbo;
-	/* One for TTM and one for the CS job */
-	p->uf_entry.tv.num_shared = 2;
+	/* One for TTM and two for the CS job */
+	p->uf_entry.tv.num_shared = 3;
 
 	drm_gem_object_put(gobj);
 

drivers/gpu/drm/amd/amdgpu/amdgpu_object.c

···
 		return;
 	}
 
-	if (shared)
-		dma_resv_add_shared_fence(resv, fence);
-	else
-		dma_resv_add_excl_fence(resv, fence);
+	dma_resv_add_fence(resv, fence, shared ? DMA_RESV_USAGE_READ :
+			   DMA_RESV_USAGE_WRITE);
 }
 
 /**

drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c

···
 
 	for (i = 0; i < submit->nr_bos; i++) {
 		struct drm_gem_object *obj = &submit->bos[i].obj->base;
+		bool write = submit->bos[i].flags & ETNA_SUBMIT_BO_WRITE;
 
-		if (submit->bos[i].flags & ETNA_SUBMIT_BO_WRITE)
-			dma_resv_add_excl_fence(obj->resv,
-							  submit->out_fence);
-		else
-			dma_resv_add_shared_fence(obj->resv,
-							    submit->out_fence);
-
+		dma_resv_add_fence(obj->resv, submit->out_fence, write ?
+				   DMA_RESV_USAGE_WRITE : DMA_RESV_USAGE_READ);
 		submit_unlock_object(submit, i);
 	}
 }

drivers/gpu/drm/i915/gem/i915_gem_busy.c

···
 		if (dma_resv_iter_is_restarted(&cursor))
 			args->busy = 0;
 
-		if (dma_resv_iter_is_exclusive(&cursor))
-			/* Translate the exclusive fence to the READ *and* WRITE engine */
+		if (dma_resv_iter_usage(&cursor) <= DMA_RESV_USAGE_WRITE)
+			/* Translate the write fences to the READ *and* WRITE engine */
 			args->busy |= busy_check_writer(fence);
 		else
-			/* Translate shared fences to READ set of engines */
+			/* Translate read fences to READ set of engines */
 			args->busy |= busy_check_reader(fence);
 	}
 	dma_resv_iter_end(&cursor);

drivers/gpu/drm/i915/gem/i915_gem_clflush.c

···
 						obj->base.resv, NULL, true,
 						i915_fence_timeout(i915),
 						I915_FENCE_GFP);
-		dma_resv_add_excl_fence(obj->base.resv, &clflush->base.dma);
+		dma_resv_add_fence(obj->base.resv, &clflush->base.dma,
+				   DMA_RESV_USAGE_WRITE);
 		dma_fence_work_commit(&clflush->base);
 		/*
 		 * We must have successfully populated the pages(since we are

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

···
 	if (IS_ERR_OR_NULL(copy_fence))
 		return PTR_ERR_OR_ZERO(copy_fence);
 
-	dma_resv_add_excl_fence(dst_bo->base.resv, copy_fence);
-	dma_resv_add_shared_fence(src_bo->base.resv, copy_fence);
-
+	dma_resv_add_fence(dst_bo->base.resv, copy_fence, DMA_RESV_USAGE_WRITE);
+	dma_resv_add_fence(src_bo->base.resv, copy_fence, DMA_RESV_USAGE_READ);
 	dma_fence_put(copy_fence);
 
 	return 0;

drivers/gpu/drm/i915/gem/selftests/i915_gem_migrate.c

···
 		if (rq) {
 			err = dma_resv_reserve_fences(obj->base.resv, 1);
 			if (!err)
-				dma_resv_add_excl_fence(obj->base.resv,
-							&rq->fence);
+				dma_resv_add_fence(obj->base.resv, &rq->fence,
+						   DMA_RESV_USAGE_WRITE);
 			i915_gem_object_set_moving_fence(obj, &rq->fence);
 			i915_request_put(rq);
 		}

drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c

···
 					  expand32(POISON_INUSE), &rq);
 	i915_gem_object_unpin_pages(obj);
 	if (rq) {
-		dma_resv_add_excl_fence(obj->base.resv, &rq->fence);
+		dma_resv_add_fence(obj->base.resv, &rq->fence,
+				   DMA_RESV_USAGE_WRITE);
 		i915_gem_object_set_moving_fence(obj, &rq->fence);
 		i915_request_put(rq);
 	}

drivers/gpu/drm/i915/i915_vma.c

···
 		}
 
 		if (fence) {
-			dma_resv_add_excl_fence(vma->obj->base.resv, fence);
+			dma_resv_add_fence(vma->obj->base.resv, fence,
+					   DMA_RESV_USAGE_WRITE);
 			obj->write_domain = I915_GEM_DOMAIN_RENDER;
 			obj->read_domains = 0;
 		}
···
 		}
 
 		if (fence) {
-			dma_resv_add_shared_fence(vma->obj->base.resv, fence);
+			dma_resv_add_fence(vma->obj->base.resv, fence,
+					   DMA_RESV_USAGE_READ);
 			obj->write_domain = 0;
 		}
 	}
···
 		goto out_rpm;
 	}
 
-	dma_resv_add_shared_fence(obj->base.resv, fence);
+	dma_resv_add_fence(obj->base.resv, fence, DMA_RESV_USAGE_READ);
 	dma_fence_put(fence);
 
 out_rpm:

drivers/gpu/drm/i915/selftests/intel_memory_region.c

···
 					  obj->mm.pages->sgl, I915_CACHE_NONE,
 					  true, 0xdeadbeaf, &rq);
 	if (rq) {
-		dma_resv_add_excl_fence(obj->base.resv, &rq->fence);
+		dma_resv_add_fence(obj->base.resv, &rq->fence,
+				   DMA_RESV_USAGE_WRITE);
 		i915_request_put(rq);
 	}
 

drivers/gpu/drm/lima/lima_gem.c

···
 	fence = lima_sched_context_queue_task(submit->task);
 
 	for (i = 0; i < submit->nr_bos; i++) {
-		if (submit->bos[i].flags & LIMA_SUBMIT_BO_WRITE)
-			dma_resv_add_excl_fence(lima_bo_resv(bos[i]), fence);
-		else
-			dma_resv_add_shared_fence(lima_bo_resv(bos[i]), fence);
+		dma_resv_add_fence(lima_bo_resv(bos[i]), fence,
+				   submit->bos[i].flags & LIMA_SUBMIT_BO_WRITE ?
+				   DMA_RESV_USAGE_WRITE : DMA_RESV_USAGE_READ);
 	}
 
 	drm_gem_unlock_reservations((struct drm_gem_object **)bos,

drivers/gpu/drm/msm/msm_gem_submit.c

···
 		struct drm_gem_object *obj = &submit->bos[i].obj->base;
 
 		if (submit->bos[i].flags & MSM_SUBMIT_BO_WRITE)
-			dma_resv_add_excl_fence(obj->resv, submit->user_fence);
+			dma_resv_add_fence(obj->resv, submit->user_fence,
+					   DMA_RESV_USAGE_WRITE);
 		else if (submit->bos[i].flags & MSM_SUBMIT_BO_READ)
-			dma_resv_add_shared_fence(obj->resv, submit->user_fence);
+			dma_resv_add_fence(obj->resv, submit->user_fence,
+					   DMA_RESV_USAGE_READ);
 	}
 }
 

drivers/gpu/drm/nouveau/nouveau_bo.c

···
 {
 	struct dma_resv *resv = nvbo->bo.base.resv;
 
-	if (exclusive)
-		dma_resv_add_excl_fence(resv, &fence->base);
-	else if (fence)
-		dma_resv_add_shared_fence(resv, &fence->base);
+	if (!fence)
+		return;
+
+	dma_resv_add_fence(resv, &fence->base, exclusive ?
+			   DMA_RESV_USAGE_WRITE : DMA_RESV_USAGE_READ);
 }
 
 static void

drivers/gpu/drm/nouveau/nouveau_fence.c

···
 		dma_resv_for_each_fence(&cursor, resv,
 					dma_resv_usage_rw(exclusive),
 					fence) {
+			enum dma_resv_usage usage;
 			struct nouveau_fence *f;
 
-			if (i == 0 && dma_resv_iter_is_exclusive(&cursor))
+			usage = dma_resv_iter_usage(&cursor);
+			if (i == 0 && usage == DMA_RESV_USAGE_WRITE)
 				continue;
 
 			f = nouveau_local_fence(fence, chan->drm);

drivers/gpu/drm/panfrost/panfrost_job.c

···
 	int i;
 
 	for (i = 0; i < bo_count; i++)
-		dma_resv_add_excl_fence(bos[i]->resv, fence);
+		dma_resv_add_fence(bos[i]->resv, fence, DMA_RESV_USAGE_WRITE);
 }
 
 int panfrost_job_push(struct panfrost_job *job)

drivers/gpu/drm/qxl/qxl_release.c

···
 	list_for_each_entry(entry, &release->bos, head) {
 		bo = entry->bo;
 
-		dma_resv_add_shared_fence(bo->base.resv, &release->base);
+		dma_resv_add_fence(bo->base.resv, &release->base,
+				   DMA_RESV_USAGE_READ);
 		ttm_bo_move_to_lru_tail_unlocked(bo);
 		dma_resv_unlock(bo->base.resv);
 	}

drivers/gpu/drm/radeon/radeon_object.c

···
 		return;
 	}
 
-	if (shared)
-		dma_resv_add_shared_fence(resv, &fence->base);
-	else
-		dma_resv_add_excl_fence(resv, &fence->base);
+	dma_resv_add_fence(resv, &fence->base, shared ?
+			   DMA_RESV_USAGE_READ : DMA_RESV_USAGE_WRITE);
 }

drivers/gpu/drm/ttm/ttm_bo.c

···
 		return ret;
 	}
 
-	dma_resv_add_shared_fence(bo->base.resv, fence);
+	dma_resv_add_fence(bo->base.resv, fence, DMA_RESV_USAGE_WRITE);
 
 	ret = dma_resv_reserve_fences(bo->base.resv, 1);
 	if (unlikely(ret)) {

drivers/gpu/drm/ttm/ttm_bo_util.c

···
 	if (ret)
 		return ret;
 
-	dma_resv_add_excl_fence(&ghost_obj->base._resv, fence);
+	dma_resv_add_fence(&ghost_obj->base._resv, fence,
+			   DMA_RESV_USAGE_WRITE);
 
 	/**
 	 * If we're not moving to fixed memory, the TTM object
···
 	struct ttm_resource_manager *man = ttm_manager_type(bdev, new_mem->mem_type);
 	int ret = 0;
 
-	dma_resv_add_excl_fence(bo->base.resv, fence);
+	dma_resv_add_fence(bo->base.resv, fence, DMA_RESV_USAGE_WRITE);
 	if (!evict)
 		ret = ttm_bo_move_to_ghost(bo, fence, man->use_tt);
 	else if (!from->use_tt && pipeline)

drivers/gpu/drm/ttm/ttm_execbuf_util.c

···
 	list_for_each_entry(entry, list, head) {
 		struct ttm_buffer_object *bo = entry->bo;
 
-		if (entry->num_shared)
-			dma_resv_add_shared_fence(bo->base.resv, fence);
-		else
-			dma_resv_add_excl_fence(bo->base.resv, fence);
+		dma_resv_add_fence(bo->base.resv, fence, entry->num_shared ?
+				   DMA_RESV_USAGE_READ : DMA_RESV_USAGE_WRITE);
 		ttm_bo_move_to_lru_tail_unlocked(bo);
 		dma_resv_unlock(bo->base.resv);
 	}

drivers/gpu/drm/v3d/v3d_gem.c

···
 
 	for (i = 0; i < job->bo_count; i++) {
 		/* XXX: Use shared fences for read-only objects. */
-		dma_resv_add_excl_fence(job->bo[i]->resv,
-					job->done_fence);
+		dma_resv_add_fence(job->bo[i]->resv, job->done_fence,
+				   DMA_RESV_USAGE_WRITE);
 	}
 
 	drm_gem_unlock_reservations(job->bo, job->bo_count, acquire_ctx);

drivers/gpu/drm/vc4/vc4_gem.c

···
 		bo = to_vc4_bo(&exec->bo[i]->base);
 		bo->seqno = seqno;
 
-		dma_resv_add_shared_fence(bo->base.base.resv, exec->fence);
+		dma_resv_add_fence(bo->base.base.resv, exec->fence);
 	}
 
 	list_for_each_entry(bo, &exec->unref_list, unref_head) {

drivers/gpu/drm/vgem/vgem_fence.c

···
 	/* Expose the fence via the dma-buf */
 	dma_resv_lock(resv, NULL);
 	ret = dma_resv_reserve_fences(resv, 1);
-	if (!ret) {
-		if (arg->flags & VGEM_FENCE_WRITE)
-			dma_resv_add_excl_fence(resv, fence);
-		else
-			dma_resv_add_shared_fence(resv, fence);
-	}
+	if (!ret)
+		dma_resv_add_fence(resv, fence, arg->flags & VGEM_FENCE_WRITE ?
+				   DMA_RESV_USAGE_WRITE : DMA_RESV_USAGE_READ);
 	dma_resv_unlock(resv);
 
 	/* Record the fence in our idr for later signaling */

drivers/gpu/drm/virtio/virtgpu_gem.c

···
 	int i;
 
 	for (i = 0; i < objs->nents; i++)
-		dma_resv_add_excl_fence(objs->objs[i]->resv, fence);
+		dma_resv_add_fence(objs->objs[i]->resv, fence,
+				   DMA_RESV_USAGE_WRITE);
 }
 
 void virtio_gpu_array_put_free(struct virtio_gpu_object_array *objs)

drivers/gpu/drm/vmwgfx/vmwgfx_bo.c

···
 
 	ret = dma_resv_reserve_fences(bo->base.resv, 1);
 	if (!ret)
-		dma_resv_add_excl_fence(bo->base.resv, &fence->base);
+		dma_resv_add_fence(bo->base.resv, &fence->base,
+				   DMA_RESV_USAGE_WRITE);
 	else
 		/* Last resort fallback when we are OOM */
 		dma_fence_wait(&fence->base, false);

include/linux/dma-buf.h

···
 	 * e.g. exposed in `Implicit Fence Poll Support`_ must follow the
 	 * below rules.
 	 *
-	 * - Drivers must add a shared fence through dma_resv_add_shared_fence()
-	 *   for anything the userspace API considers a read access. This highly
-	 *   depends upon the API and window system.
+	 * - Drivers must add a read fence through dma_resv_add_fence() with the
+	 *   DMA_RESV_USAGE_READ flag for anything the userspace API considers a
+	 *   read access. This highly depends upon the API and window system.
 	 *
-	 * - Similarly drivers must set the exclusive fence through
-	 *   dma_resv_add_excl_fence() for anything the userspace API considers
-	 *   write access.
+	 * - Similarly drivers must add a write fence through
+	 *   dma_resv_add_fence() with the DMA_RESV_USAGE_WRITE flag for
+	 *   anything the userspace API considers write access.
 	 *
-	 * - Drivers may just always set the exclusive fence, since that only
+	 * - Drivers may just always add a write fence, since that only
 	 *   causes unecessarily synchronization, but no correctness issues.
 	 *
 	 * - Some drivers only expose a synchronous userspace API with no
···
 	 * Dynamic importers, see dma_buf_attachment_is_dynamic(), have
 	 * additional constraints on how they set up fences:
 	 *
-	 * - Dynamic importers must obey the exclusive fence and wait for it to
+	 * - Dynamic importers must obey the write fences and wait for them to
 	 *   signal before allowing access to the buffer's underlying storage
 	 *   through the device.
 	 *

include/linux/dma-resv.h

···
 	/** @fence: the currently handled fence */
 	struct dma_fence *fence;
 
+	/** @fence_usage: the usage of the current fence */
+	enum dma_resv_usage fence_usage;
+
 	/** @seq: sequence number to check for modifications */
 	unsigned int seq;
 
···
 }
 
 /**
- * dma_resv_iter_is_exclusive - test if the current fence is the exclusive one
+ * dma_resv_iter_usage - Return the usage of the current fence
  * @cursor: the cursor of the current position
  *
- * Returns true if the currently returned fence is the exclusive one.
+ * Returns the usage of the currently processed fence.
  */
-static inline bool dma_resv_iter_is_exclusive(struct dma_resv_iter *cursor)
+static inline enum dma_resv_usage
+dma_resv_iter_usage(struct dma_resv_iter *cursor)
 {
-	return cursor->index == 0;
+	return cursor->fence_usage;
 }
 
 /**
···
 #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
 
 #ifdef CONFIG_DEBUG_MUTEXES
-void dma_resv_reset_shared_max(struct dma_resv *obj);
+void dma_resv_reset_max_fences(struct dma_resv *obj);
 #else
-static inline void dma_resv_reset_shared_max(struct dma_resv *obj) {}
+static inline void dma_resv_reset_max_fences(struct dma_resv *obj) {}
 #endif
 
 /**
···
  */
 static inline void dma_resv_unlock(struct dma_resv *obj)
 {
-	dma_resv_reset_shared_max(obj);
+	dma_resv_reset_max_fences(obj);
 	ww_mutex_unlock(&obj->lock);
 }
 
 void dma_resv_init(struct dma_resv *obj);
 void dma_resv_fini(struct dma_resv *obj);
 int dma_resv_reserve_fences(struct dma_resv *obj, unsigned int num_fences);
-void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
+void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence,
+			enum dma_resv_usage usage);
 void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
-			     struct dma_fence *fence);
-void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
+			     struct dma_fence *fence,
+			     enum dma_resv_usage usage);
 int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
 			unsigned int *num_fences, struct dma_fence ***fences);
 int dma_resv_get_singleton(struct dma_resv *obj, enum dma_resv_usage usage,