Re: [PATCH v19 03/30] drm/gem: Document locking rule of vmap and evict callbacks

From: Boris Brezillon <boris.brezillon@collabora.com>
To: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Cc: "David Airlie" <airlied@gmail.com>,
	"Gerd Hoffmann" <kraxel@redhat.com>,
	"Gurchetan Singh" <gurchetansingh@chromium.org>,
	"Chia-I Wu" <olvaffe@gmail.com>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Maxime Ripard" <mripard@kernel.org>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"Christian König" <christian.koenig@amd.com>,
	"Qiang Yu" <yuq825@gmail.com>,
	"Steven Price" <steven.price@arm.com>,
	"Emma Anholt" <emma@anholt.net>, "Melissa Wen" <mwen@igalia.com>,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	kernel@collabora.com, virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v19 03/30] drm/gem: Document locking rule of vmap and evict callbacks
Date: Thu, 25 Jan 2024 08:55:02 +0100	[thread overview]
Message-ID: <20240125085502.3207ee29@collabora.com> (raw)
In-Reply-To: <20240105184624.508603-4-dmitry.osipenko@collabora.com>

On Fri,  5 Jan 2024 21:45:57 +0300
Dmitry Osipenko <dmitry.osipenko@collabora.com> wrote:

> The vmap/vunmap/evict GEM callbacks are always invoked with a held GEM's
> reservation lock. Document this locking rule for clarity.
> 
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>

> ---
>  include/drm/drm_gem.h | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
> index f835fdee6a5e..021f64371056 100644
> --- a/include/drm/drm_gem.h
> +++ b/include/drm/drm_gem.h
> @@ -156,7 +156,8 @@ struct drm_gem_object_funcs {
>  	 * @vmap:
>  	 *
>  	 * Returns a virtual address for the buffer. Used by the
> -	 * drm_gem_dmabuf_vmap() helper.
> +	 * drm_gem_dmabuf_vmap() helper. Called with a held GEM reservation
> +	 * lock.
>  	 *
>  	 * This callback is optional.
>  	 */
> @@ -166,7 +167,8 @@ struct drm_gem_object_funcs {
>  	 * @vunmap:
>  	 *
>  	 * Releases the address previously returned by @vmap. Used by the
> -	 * drm_gem_dmabuf_vunmap() helper.
> +	 * drm_gem_dmabuf_vunmap() helper. Called with a held GEM reservation
> +	 * lock.
>  	 *
>  	 * This callback is optional.
>  	 */
> @@ -189,7 +191,8 @@ struct drm_gem_object_funcs {
>  	 * @evict:
>  	 *
>  	 * Evicts gem object out from memory. Used by the drm_gem_object_evict()
> -	 * helper. Returns 0 on success, -errno otherwise.
> +	 * helper. Returns 0 on success, -errno otherwise. Called with a held
> +	 * GEM reservation lock.
>  	 *
>  	 * This callback is optional.
>  	 */