[PATCH v2 03/10] drm/client: Depend on GEM object kmap ref-counting

[Thomas Zimmermann]

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 at suse.de>
---
 drivers/gpu/drm/drm_client.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
index fe573acf1067..ce45e380f4a2 100644
--- a/drivers/gpu/drm/drm_client.c
+++ b/drivers/gpu/drm/drm_client.c
@@ -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;
 	int ret;
 
-	if (dma_buf_map_is_set(map))
-		goto out;
-
 	/*
 	 * FIXME: The dependency on GEM here isn't required, we could
 	 * 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)
 		return ret;
 
-out:
 	*map_copy = *map;
 
 	return 0;
-- 
2.29.2