Commits
Laurent Pinchart committed 17f0efc4f46
drm/shmobile: Fix race condition between page flip request and handler The page flip handler stores the page flip event pointer and then calls drm_vblank_get() to enable the vblank interrupt. Due to the vblank off delay, the vblank interrupt can be enabled in the hardware at that point, even if the vblank reference count is equal to 0. If a vblank interrupt is triggered between storing the event pointer and calling drm_vblank_get(), the page flip completion handler will process the event and call drm_vblank_put() with a reference count equal to 0. This will result in a BUG_ON. Fix the race condition by calling drm_vblank_get() before storing the event pointer. Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Signed-off-by: Dave Airlie <airlied@redhat.com>