Use atomic kref helper for pages_use_count to optimize pin/unpin functions by skipping reservation locking while GEM's pin refcount > 1. Suggested-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx> --- drivers/gpu/drm/drm_gem_shmem_helper.c | 48 ++++++++++++++----------- drivers/gpu/drm/lima/lima_gem.c | 2 +- drivers/gpu/drm/panfrost/panfrost_mmu.c | 2 +- include/drm/drm_gem_shmem_helper.h | 2 +- 4 files changed, 30 insertions(+), 24 deletions(-) diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index 1a7e5c332fd8..5a2e37b3e51d 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -155,7 +155,7 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem) if (shmem->got_sgt) drm_gem_shmem_put_pages_locked(shmem); - drm_WARN_ON(obj->dev, shmem->pages_use_count); + drm_WARN_ON(obj->dev, kref_read(&shmem->pages_use_count)); dma_resv_unlock(shmem->base.resv); } @@ -172,14 +172,13 @@ 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 (kref_get_unless_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); } @@ -195,26 +194,20 @@ static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem) shmem->pages = pages; + kref_init(&shmem->pages_use_count); + return 0; } -/* - * drm_gem_shmem_put_pages_locked - Decrease use count on the backing pages for a shmem GEM object - * @shmem: shmem GEM object - * - * This function decreases the use count and puts the backing pages when use drops to zero. - */ -void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem) -{ - struct drm_gem_object *obj = &shmem->base; - - dma_resv_assert_held(shmem->base.resv); - if (drm_WARN_ON_ONCE(obj->dev, !shmem->pages_use_count)) - return; +static void drm_gem_shmem_kref_release_pages(struct kref *kref) +{ + struct drm_gem_shmem_object *shmem; + struct drm_gem_object *obj; - if (--shmem->pages_use_count > 0) - return; + shmem = container_of(kref, struct drm_gem_shmem_object, + pages_use_count); + obj = &shmem->base; #ifdef CONFIG_X86 if (shmem->map_wc) @@ -226,6 +219,19 @@ void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem) shmem->pages_mark_accessed_on_put); shmem->pages = NULL; } + +/* + * drm_gem_shmem_put_pages_locked - Decrease use count on the backing pages for a shmem GEM object + * @shmem: shmem GEM object + * + * This function decreases the use count and puts the backing pages when use drops to zero. + */ +void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem) +{ + dma_resv_assert_held(shmem->base.resv); + + kref_put(&shmem->pages_use_count, drm_gem_shmem_kref_release_pages); +} EXPORT_SYMBOL_GPL(drm_gem_shmem_put_pages_locked); static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem) @@ -556,8 +562,8 @@ 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, + !kref_get_unless_zero(&shmem->pages_use_count)); dma_resv_unlock(shmem->base.resv); @@ -638,7 +644,7 @@ void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem, if (shmem->base.import_attach) return; - drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count); + drm_printf_indent(p, indent, "pages_use_count=%u\n", kref_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); } diff --git a/drivers/gpu/drm/lima/lima_gem.c b/drivers/gpu/drm/lima/lima_gem.c index 7d74c71f5558..a5f015d188cd 100644 --- a/drivers/gpu/drm/lima/lima_gem.c +++ b/drivers/gpu/drm/lima/lima_gem.c @@ -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; + kref_init(&bo->base.pages_use_count); mapping_set_unevictable(mapping); } diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c index 7771769f0ce0..c9ac9d361864 100644 --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c @@ -487,7 +487,7 @@ 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; + kref_init(&bo->base.pages_use_count); } else { pages = bo->base.pages; if (pages[page_offset]) { diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h index afb7cd671e2a..a5a3c193cc8f 100644 --- a/include/drm/drm_gem_shmem_helper.h +++ b/include/drm/drm_gem_shmem_helper.h @@ -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; + struct kref pages_use_count; /** * @pages_pin_count: -- 2.41.0