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drm/client: Depend on GEM object kmap ref-counting 

DRM client's vmap/vunmap functions don't allow for multiple vmap
operations. Calling drm_client_buffer_vmap() twice returns the same
mapping, then calling drm_client_buffer_vunmap() twice already unmaps
on the first call. This leads to unbalanced vmap refcounts. Fix this
by calling drm_gem_vmap() unconditionally in drm_client_buffer_vmap().

All drivers that support DRM clients have to implement correct ref-
counting for their vmap operations, or not vunmap at all. This is the
case for drivers that use CMA, SHMEM and VRAM helpers, and QXL. Other
drivers are not affected.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20201120102545.4047-4-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2020-11-20 11:25:38 +01:00
parent 763aea17bf
commit c1acbf08eb
1 changed files with 0 additions and 4 deletions
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4
drivers/gpu/drm/drm_client.c
View File

@ -314,9 +314,6 @@ drm_client_buffer_vmap(struct drm_client_buffer *buffer, struct dma_buf_map *map
struct dma_buf_map *map = &buffer->map; struct dma_buf_map *map = &buffer->map;
int ret; int ret;
if (dma_buf_map_is_set(map))
goto out;
/* /*
* FIXME: The dependency on GEM here isn't required, we could * FIXME: The dependency on GEM here isn't required, we could
* convert the driver handle to a dma-buf instead and use the * convert the driver handle to a dma-buf instead and use the
@ -329,7 +326,6 @@ drm_client_buffer_vmap(struct drm_client_buffer *buffer, struct dma_buf_map *map
if (ret) if (ret)
return ret; return ret;
out:
*map_copy = *map; *map_copy = *map;
return 0; return 0;