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drm/i915: Fix locking in DRRS flush/invalidate hooks

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We must acquire the mutex before we can check drrs.dp, otherwise
someone might sneak in with a modeset, clear the pointer after we've
checked it and then the code will Oops.

This issue has been introduced in

commit a93fad0f7f
Author: Vandana Kannan <vandana.kannan@intel.com>
Date:   Sat Jan 10 02:25:59 2015 +0530

    drm/i915: DRRS calls based on frontbuffer

v2: Don't blow up on uninitialized mutex and work item by checking
whether DRRS is support or not first. Also unconditionally initialize
the mutex/work item to avoid future trouble.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Ramalingam C <ramalingam.c@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Vandana Kannan <vandana.kannan@intel.com>
Cc: stable@vger.kernel.org (4.0+ only)
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
Daniel Vetter 2015-04-09 16:44:15 +02:00 committed by Jani Nikula
parent 6e0aa8018f
commit 9da7d69357
1 changed files with 15 additions and 7 deletions
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22
drivers/gpu/drm/i915/intel_dp.c
View file

@ -5157,7 +5157,6 @@ static void intel_edp_drrs_downclock_work(struct work_struct *work)
downclock_mode->vrefresh);
unlock:
mutex_unlock(&dev_priv->drrs.mutex);
}
@ -5179,12 +5178,17 @@ void intel_edp_drrs_invalidate(struct drm_device *dev,
struct drm_crtc *crtc;
enum pipe pipe;
if (!dev_priv->drrs.dp)
if (dev_priv->drrs.type == DRRS_NOT_SUPPORTED)
return;
cancel_delayed_work_sync(&dev_priv->drrs.work);
mutex_lock(&dev_priv->drrs.mutex);
if (!dev_priv->drrs.dp) {
mutex_unlock(&dev_priv->drrs.mutex);
return;
}
crtc = dp_to_dig_port(dev_priv->drrs.dp)->base.base.crtc;
pipe = to_intel_crtc(crtc)->pipe;
@ -5218,12 +5222,17 @@ void intel_edp_drrs_flush(struct drm_device *dev,
struct drm_crtc *crtc;
enum pipe pipe;
if (!dev_priv->drrs.dp)
if (dev_priv->drrs.type == DRRS_NOT_SUPPORTED)
return;
cancel_delayed_work_sync(&dev_priv->drrs.work);
mutex_lock(&dev_priv->drrs.mutex);
if (!dev_priv->drrs.dp) {
mutex_unlock(&dev_priv->drrs.mutex);
return;
}
crtc = dp_to_dig_port(dev_priv->drrs.dp)->base.base.crtc;
pipe = to_intel_crtc(crtc)->pipe;
dev_priv->drrs.busy_frontbuffer_bits &= ~frontbuffer_bits;
@ -5294,6 +5303,9 @@ intel_dp_drrs_init(struct intel_connector *intel_connector,
struct drm_i915_private *dev_priv = dev->dev_private;
struct drm_display_mode *downclock_mode = NULL;
INIT_DELAYED_WORK(&dev_priv->drrs.work, intel_edp_drrs_downclock_work);
mutex_init(&dev_priv->drrs.mutex);
if (INTEL_INFO(dev)->gen <= 6) {
DRM_DEBUG_KMS("DRRS supported for Gen7 and above\n");
return NULL;
@ -5312,10 +5324,6 @@ intel_dp_drrs_init(struct intel_connector *intel_connector,
return NULL;
}
INIT_DELAYED_WORK(&dev_priv->drrs.work, intel_edp_drrs_downclock_work);
mutex_init(&dev_priv->drrs.mutex);
dev_priv->drrs.type = dev_priv->vbt.drrs_type;
dev_priv->drrs.refresh_rate_type = DRRS_HIGH_RR;