From 56cc279b29c7b204fe7d0943509ae209b8b128db Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Wed, 6 Aug 2014 14:49:51 +0300 Subject: [PATCH] drm: Fix deadlock between event_lock and vbl_lock/vblank_time_lock MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Currently both drm_irq.c and several drivers call drm_vblank_put() while holding event_lock. Now that drm_vblank_put() can disable the vblank interrupt directly it may need to grab vbl_lock and vblank_time_lock. That causes deadlocks since we take the locks in the opposite order in two places in drm_irq.c. So let's make sure the locking order is always event_lock->vbl_lock->vblank_time_lock. In drm_vblank_off() pull up event_lock from underneath vbl_lock. Hold the event_lock across the whole operation to make sure we only send out the events that were on the queue when we disabled the interrupt, and not ones that got added just after (assuming drm_vblank_on() already managed to get called somewhere between). To sort the other deadlock pull the event_lock out from drm_handle_vblank_events() into drm_handle_vblank() to be taken outside vblank_time_lock. Add the appropriate assert_spin_locked() to drm_handle_vblank_events(). Reviewed-by: Matt Roper Signed-off-by: Ville Syrjälä Signed-off-by: Daniel Vetter --- Reading git-format-patch failed