diff mbox

[0737/1094] drm/i915: Fix deadlock during driver init on ILK

Message ID 1413889294-31328-738-git-send-email-dheerajx.s.jamwal@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Dheeraj Jamwal Oct. 21, 2014, 10:55 a.m. UTC 
From: Ville Syrjälä <ville.syrjala@linux.intel.com>

We have a struct_mutex deadlock during driver init on ILK

[   54.320273] =============================================
[   54.320371] [ INFO: possible recursive locking detected ]
[   54.320471] 3.15.0-rc2-flip_race+ #2 Not tainted
[   54.320567] ---------------------------------------------
[   54.320665] modprobe/2178 is trying to acquire lock:
[   54.320762]  (&dev->struct_mutex){+.+.+.}, at: [<ffffffffa0568b05>] intel_enable_gt_powersave+0xa5/0x9d0 [i915]
[   54.321111]
[   54.321111] but task is already holding lock:
[   54.321250]  (&dev->struct_mutex){+.+.+.}, at: [<ffffffffa05b4c2e>] intel_modeset_init_hw+0x3e/0x60 [i915]
[   54.321583]
[   54.321583] other info that might help us debug this:
[   54.321724]  Possible unsafe locking scenario:
[   54.321724]
[   54.321863]        CPU0
[   54.321954]        ----
[   54.322046]   lock(&dev->struct_mutex);
[   54.322221]   lock(&dev->struct_mutex);
[   54.322397]
[   54.322397]  *** DEADLOCK ***
[   54.322397]
[   54.322638]  May be due to missing lock nesting notation
[   54.322638]
[   54.322781] 4 locks held by modprobe/2178:
[   54.322875]  #0:  (&dev->mutex){......}, at: [<ffffffff813592eb>] __driver_attach+0x5b/0xb0
[   54.323230]  #1:  (&dev->mutex){......}, at: [<ffffffff813592f9>] __driver_attach+0x69/0xb0
[   54.323582]  #2:  (drm_global_mutex){+.+.+.}, at: [<ffffffffa04e1e0d>] drm_dev_register+0x2d/0x120 [drm]
[   54.323945]  #3:  (&dev->struct_mutex){+.+.+.}, at: [<ffffffffa05b4c2e>] intel_modeset_init_hw+0x3e/0x60 [i915]

This regression got introduced in:
 commit 586d5270b60dc1f35cc3ca982d403765bad77965
 Author: Imre Deak <imre.deak@intel.com>
 Date:   Mon Apr 14 20:24:28 2014 +0300

    drm/i915: move getting struct_mutex lower in the callstack during GPU reset

Fix the problem by not taking struct_mutex around intel_enable_gt_powersave()
in intel_modeset_init_hw() since intel_enable_gt_powersave() now grabs the
mutex itself.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit 8a6543ba4719ff940b22ce9f9830a9c3fd9e1b60)

Signed-off-by: Dheeraj Jamwal <dheerajx.s.jamwal@intel.com>
---
 drivers/gpu/drm/i915/intel_display.c |    2 --
 1 file changed, 2 deletions(-)
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index df7de85..8652ea1 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -11245,9 +11245,7 @@  void intel_modeset_init_hw(struct drm_device *dev)
 
 	intel_reset_dpio(dev);
 
-	mutex_lock(&dev->struct_mutex);
 	intel_enable_gt_powersave(dev);
-	mutex_unlock(&dev->struct_mutex);
 }
 
 void intel_modeset_suspend_hw(struct drm_device *dev)