[3.11.y.z extended stable] Patch "drm/i915: Don't grab crtc mutexes in intel_modeset_gem_init()" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    drm/i915: Don't grab crtc mutexes in intel_modeset_gem_init()

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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>From 23a9c8a14e2e62ffab0202da8aba224ea0dea375 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala at linux.intel.com>
Date: Tue, 7 Jan 2014 16:15:36 +0200
Subject: drm/i915: Don't grab crtc mutexes in intel_modeset_gem_init()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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commit 7ad228b11ec26a820291c9f5a1168d6176580dc1 upstream.

When the pipe A force quirk is applied the code will attempt to grab
a crtc mutex during intel_modeset_setup_hw_state(). If we're already
holding all crtc mutexes this will obviously deadlock every time.

So instead of using drm_modeset_lock_all() just grab the
mode_config.mutex. This is enough to avoid the unlocked mutex warnings
from certain lower level functions.

The regression was introduced in:

 commit 027476642811f8559cbe00ef6cc54db230e48a20
 Author: Ville Syrjälä <ville.syrjala at linux.intel.com>
 Date:   Mon Dec 2 11:08:06 2013 +0200

    drm/i915: Take modeset locks around intel_modeset_setup_hw_state()

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
[danvet: Add cc: stable since the offending commit has that, too.]
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/gpu/drm/i915/intel_display.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index cfe124a..0e3f213 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9993,10 +9993,10 @@ void intel_modeset_gem_init(struct drm_device *dev)

 	intel_setup_overlay(dev);

-	drm_modeset_lock_all(dev);
+	mutex_lock(&dev->mode_config.mutex);
 	drm_mode_config_reset(dev);
 	intel_modeset_setup_hw_state(dev, false);
-	drm_modeset_unlock_all(dev);
+	mutex_unlock(&dev->mode_config.mutex);
 }

 void intel_modeset_cleanup(struct drm_device *dev)
--
1.8.3.2