Commit 051b6646 authored by Dmitry Osipenko's avatar Dmitry Osipenko
Browse files

drm/shmem-helper: Use refcount_t for pages_use_count 



Use atomic refcount_t helper for pages_use_count to optimize pin/unpin
functions by skipping reservation locking while GEM's pin refcount > 1.

Acked-by: default avatarMaxime Ripard <mripard@kernel.org>
Reviewed-by: default avatarBoris Brezillon <boris.brezillon@collabora.com>
Suggested-by: default avatarBoris Brezillon <boris.brezillon@collabora.com>
Acked-by: default avatarThomas Zimmermann <tzimmermann@suse.d>
Signed-off-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250322212608.40511-9-dmitry.osipenko@collabora.com
parent d586b535

drivers/gpu/drm/drm_gem_shmem_helper.c

+15 −18
Original line number Diff line number Diff line
@@ -176,7 +176,7 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem) 
		if (shmem->pages)

			drm_gem_shmem_put_pages_locked(shmem);



		drm_WARN_ON(obj->dev, shmem->pages_use_count);

		drm_WARN_ON(obj->dev, refcount_read(&shmem->pages_use_count));

		drm_WARN_ON(obj->dev, refcount_read(&shmem->pages_pin_count));



		dma_resv_unlock(shmem->base.resv);
@@ -194,14 +194,13 @@ static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem) 


	dma_resv_assert_held(shmem->base.resv);



	if (shmem->pages_use_count++ > 0)

	if (refcount_inc_not_zero(&shmem->pages_use_count))

		return 0;



	pages = drm_gem_get_pages(obj);

	if (IS_ERR(pages)) {

		drm_dbg_kms(obj->dev, "Failed to get pages (%ld)\n",

			    PTR_ERR(pages));

		shmem->pages_use_count = 0;

		return PTR_ERR(pages);

	}
@@ -217,6 +216,8 @@ static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem) 


	shmem->pages = pages;



	refcount_set(&shmem->pages_use_count, 1);



	return 0;

}
@@ -232,12 +233,7 @@ void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem) 


	dma_resv_assert_held(shmem->base.resv);



	if (drm_WARN_ON_ONCE(obj->dev, !shmem->pages_use_count))

		return;



	if (--shmem->pages_use_count > 0)

		return;



	if (refcount_dec_and_test(&shmem->pages_use_count)) {

#ifdef CONFIG_X86

		if (shmem->map_wc)

			set_pages_array_wb(shmem->pages, obj->size >> PAGE_SHIFT);
@@ -248,6 +244,7 @@ void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem) 
				  shmem->pages_mark_accessed_on_put);

		shmem->pages = NULL;

	}

}

EXPORT_SYMBOL_GPL(drm_gem_shmem_put_pages_locked);



int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
@@ -582,8 +579,8 @@ static void drm_gem_shmem_vm_open(struct vm_area_struct *vma) 
	 * mmap'd, vm_open() just grabs an additional reference for the new

	 * mm the vma is getting copied into (ie. on fork()).

	 */

	if (!drm_WARN_ON_ONCE(obj->dev, !shmem->pages_use_count))

		shmem->pages_use_count++;

	drm_WARN_ON_ONCE(obj->dev,

			 !refcount_inc_not_zero(&shmem->pages_use_count));



	dma_resv_unlock(shmem->base.resv);
@@ -674,7 +671,7 @@ void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem, 
		return;



	drm_printf_indent(p, indent, "pages_pin_count=%u\n", refcount_read(&shmem->pages_pin_count));

	drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count);

	drm_printf_indent(p, indent, "pages_use_count=%u\n", refcount_read(&shmem->pages_use_count));

	drm_printf_indent(p, indent, "vmap_use_count=%u\n", shmem->vmap_use_count);

	drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);

}

drivers/gpu/drm/lima/lima_gem.c

+1 −1
Original line number Diff line number Diff line
@@ -47,7 +47,7 @@ int lima_heap_alloc(struct lima_bo *bo, struct lima_vm *vm) 
		}



		bo->base.pages = pages;

		bo->base.pages_use_count = 1;

		refcount_set(&bo->base.pages_use_count, 1);



		mapping_set_unevictable(mapping);

	}

drivers/gpu/drm/panfrost/panfrost_mmu.c

+1 −1
Original line number Diff line number Diff line
@@ -489,7 +489,7 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as, 
			goto err_unlock;

		}

		bo->base.pages = pages;

		bo->base.pages_use_count = 1;

		refcount_set(&bo->base.pages_use_count, 1);

	} else {

		pages = bo->base.pages;

		if (pages[page_offset]) {

drivers/gpu/drm/tests/drm_gem_shmem_test.c

+4 −4
Original line number Diff line number Diff line
@@ -134,7 +134,7 @@ static void drm_gem_shmem_test_pin_pages(struct kunit *test) 
	shmem = drm_gem_shmem_create(drm_dev, TEST_SIZE);

	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, shmem);

	KUNIT_EXPECT_NULL(test, shmem->pages);

	KUNIT_EXPECT_EQ(test, shmem->pages_use_count, 0);

	KUNIT_EXPECT_EQ(test, refcount_read(&shmem->pages_use_count), 0);



	ret = kunit_add_action_or_reset(test, drm_gem_shmem_free_wrapper, shmem);

	KUNIT_ASSERT_EQ(test, ret, 0);
@@ -142,14 +142,14 @@ static void drm_gem_shmem_test_pin_pages(struct kunit *test) 
	ret = drm_gem_shmem_pin(shmem);

	KUNIT_ASSERT_EQ(test, ret, 0);

	KUNIT_ASSERT_NOT_NULL(test, shmem->pages);

	KUNIT_EXPECT_EQ(test, shmem->pages_use_count, 1);

	KUNIT_EXPECT_EQ(test, refcount_read(&shmem->pages_use_count), 1);



	for (i = 0; i < (shmem->base.size >> PAGE_SHIFT); i++)

		KUNIT_ASSERT_NOT_NULL(test, shmem->pages[i]);



	drm_gem_shmem_unpin(shmem);

	KUNIT_EXPECT_NULL(test, shmem->pages);

	KUNIT_EXPECT_EQ(test, shmem->pages_use_count, 0);

	KUNIT_EXPECT_EQ(test, refcount_read(&shmem->pages_use_count), 0);

}



/*
@@ -251,7 +251,7 @@ static void drm_gem_shmem_test_get_sg_table(struct kunit *test) 
	sgt = drm_gem_shmem_get_pages_sgt(shmem);

	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, sgt);

	KUNIT_ASSERT_NOT_NULL(test, shmem->pages);

	KUNIT_EXPECT_EQ(test, shmem->pages_use_count, 1);

	KUNIT_EXPECT_EQ(test, refcount_read(&shmem->pages_use_count), 1);

	KUNIT_EXPECT_PTR_EQ(test, sgt, shmem->sgt);



	for_each_sgtable_sg(sgt, sg, si) {

include/drm/drm_gem_shmem_helper.h

+1 −1
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ struct drm_gem_shmem_object { 
	 * Reference count on the pages table.

	 * The pages are put when the count reaches zero.

	 */

	unsigned int pages_use_count;

	refcount_t pages_use_count;



	/**

	 * @pages_pin_count: