linux-kernel - [PATCH v20 03/10] drm/gem: Document locking rule of vmap and evict callbacks

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Message-ID: <20250322212608.40511-4-dmitry.osipenko@collabora.com>
Date: Sun, 23 Mar 2025 00:26:01 +0300
From: Dmitry Osipenko <dmitry.osipenko@...labora.com>
To: David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	Christian König <christian.koenig@....com>,
	Gerd Hoffmann <kraxel@...hat.com>,
	Qiang Yu <yuq825@...il.com>,
	Steven Price <steven.price@....com>,
	Boris Brezillon <boris.brezillon@...labora.com>,
	Frank Binns <frank.binns@...tec.com>,
	Matt Coster <matt.coster@...tec.com>
Cc: dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	kernel@...labora.com
Subject: [PATCH v20 03/10] drm/gem: Document locking rule of vmap and evict callbacks

The vmap/vunmap/evict GEM callbacks are always invoked with a held GEM's
reservation lock. Document this locking rule for clarity.

Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.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 43cf3c2c7ca0..9b71f7a9f3f8 100644
--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -159,7 +159,8 @@ 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.
 	 */
@@ -169,7 +170,8 @@ 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.
 	 */
@@ -192,7 +194,8 @@ 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.
 	 */
-- 
2.49.0