Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 9da7d693 authored by Daniel Vetter's avatar Daniel Vetter Committed by Jani Nikula
Browse files

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



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 a93fad0f
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: default avatarChris Wilson <chris@chris-wilson.co.uk>
Tested-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
parent 6e0aa801

drivers/gpu/drm/i915/intel_dp.c

+15 −7
Original line number Diff line number Diff line
@@ -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;