Use kref helper for vmap_use_count to make refcounting consistent with pages_use_count and pages_pin_count that use kref. This will allow to optimize unlocked vmappings by skipping reservation locking if refcnt > 1.
Suggested-by: Boris Brezillon <[email protected]> Signed-off-by: Dmitry Osipenko <[email protected]> --- drivers/gpu/drm/drm_gem_shmem_helper.c | 37 ++++++++++++++------------ include/drm/drm_gem_shmem_helper.h | 2 +- 2 files changed, 21 insertions(+), 18 deletions(-) diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index 17a0177acb5d..d96fee3d6166 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -144,7 +144,7 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem) } else if (!shmem->imported_sgt) { dma_resv_lock(shmem->base.resv, NULL); - drm_WARN_ON(obj->dev, shmem->vmap_use_count); + drm_WARN_ON(obj->dev, kref_read(&shmem->vmap_use_count)); if (shmem->sgt) { dma_unmap_sgtable(obj->dev->dev, shmem->sgt, @@ -359,23 +359,25 @@ int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, dma_resv_assert_held(shmem->base.resv); - if (shmem->vmap_use_count++ > 0) { + if (kref_get_unless_zero(&shmem->vmap_use_count)) { iosys_map_set_vaddr(map, shmem->vaddr); return 0; } ret = drm_gem_shmem_pin_locked(shmem); if (ret) - goto err_zero_use; + return ret; if (shmem->map_wc) prot = pgprot_writecombine(prot); shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT, VM_MAP, prot); - if (!shmem->vaddr) + if (!shmem->vaddr) { ret = -ENOMEM; - else + } else { iosys_map_set_vaddr(map, shmem->vaddr); + kref_init(&shmem->vmap_use_count); + } } if (ret) { @@ -388,13 +390,22 @@ int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, err_put_pages: if (!obj->import_attach) drm_gem_shmem_unpin_locked(shmem); -err_zero_use: - shmem->vmap_use_count = 0; return ret; } EXPORT_SYMBOL_GPL(drm_gem_shmem_vmap_locked); +static void drm_gem_shmem_kref_vunmap(struct kref *kref) +{ + struct drm_gem_shmem_object *shmem; + + shmem = container_of(kref, struct drm_gem_shmem_object, + vmap_use_count); + + vunmap(shmem->vaddr); + drm_gem_shmem_unpin_locked(shmem); +} + /* * drm_gem_shmem_vunmap_locked - Unmap a virtual mapping for a shmem GEM object * @shmem: shmem GEM object @@ -416,15 +427,7 @@ void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem, dma_buf_vunmap(obj->import_attach->dmabuf, map); } else { dma_resv_assert_held(shmem->base.resv); - - if (drm_WARN_ON_ONCE(obj->dev, !shmem->vmap_use_count)) - return; - - if (--shmem->vmap_use_count > 0) - return; - - vunmap(shmem->vaddr); - drm_gem_shmem_unpin_locked(shmem); + kref_put(&shmem->vmap_use_count, drm_gem_shmem_kref_vunmap); } shmem->vaddr = NULL; @@ -663,7 +666,7 @@ void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem, return; 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, "vmap_use_count=%u\n", kref_read(&shmem->vmap_use_count)); drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr); } EXPORT_SYMBOL_GPL(drm_gem_shmem_print_info); diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h index 400ecd63f45f..0e0ccd380f66 100644 --- a/include/drm/drm_gem_shmem_helper.h +++ b/include/drm/drm_gem_shmem_helper.h @@ -81,7 +81,7 @@ struct drm_gem_shmem_object { * Reference count on the virtual address. * The address are un-mapped when the count reaches zero. */ - unsigned int vmap_use_count; + struct kref vmap_use_count; /** * @got_sgt: -- 2.41.0
