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drm/shmem-helper: Fix unsetting shmem vaddr while vmap refcount > 0

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We switched to use refcount_t for vmaps and missed to change the vunmap
code to properly unset the vmap pointer, which is now cleared while vmap's
refcount > 0. Clear the cached vmap pointer only when refcounting drops to
zero to fix the bug.

Fixes: e1fc39a923 ("drm/shmem-helper: Use refcount_t for vmap_use_count")
Reported-by: Lucas De Marchi <lucas.demarchi@intel.com>
Closes: https://lore.kernel.org/dri-devel/20250403105053.788b0f6e@collabora.com/T/#m3dca6d81bedc8d6146a56b82694624fbc6fa4c96
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Tested-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20250403142633.484660-1-dmitry.osipenko@collabora.com
This commit is contained in:
Dmitry Osipenko 2025-04-03 17:26:33 +03:00
parent 446d38554d
commit dd71776276
1 changed files with 2 additions and 2 deletions
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4
drivers/gpu/drm/drm_gem_shmem_helper.c
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@ -415,11 +415,11 @@ void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
if (refcount_dec_and_test(&shmem->vmap_use_count)) {
vunmap(shmem->vaddr);
shmem->vaddr = NULL;
drm_gem_shmem_unpin_locked(shmem);
}
}
shmem->vaddr = NULL;
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_vunmap_locked);