[PATCH] drm: Remove "protection" around drm_vma_offset_manager_destroy()

[Chris Wilson]

Using a spinlock to serialize the destroy function, within the destroy
function itself does not prevent the buggy driver from shooting
themselves in the foot - either way they still have a use-after-free
issue.

Reported-by: Jia-Ju Bai <baijiaju1990 at gmail.com>
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Davidlohr Bueso <dave at stgolabs.net>
Cc: Liviu Dudau <Liviu.Dudau at arm.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/drm_vma_manager.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_vma_manager.c b/drivers/gpu/drm/drm_vma_manager.c
index a6b2fe36b025..c5d0d2358301 100644
--- a/drivers/gpu/drm/drm_vma_manager.c
+++ b/drivers/gpu/drm/drm_vma_manager.c
@@ -103,10 +103,7 @@ EXPORT_SYMBOL(drm_vma_offset_manager_init);
  */
 void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr)
 {
-	/* take the lock to protect against buggy drivers */
-	write_lock(&mgr->vm_lock);
 	drm_mm_takedown(&mgr->vm_addr_space_mm);
-	write_unlock(&mgr->vm_lock);
 }
 EXPORT_SYMBOL(drm_vma_offset_manager_destroy);
 
-- 
2.19.0.rc1