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FAILED: patch "[PATCH] drm/i915: Fix locking in DRRS flush/invalidate hooks" failed to apply to 4.0-stable tree

PATCH [email protected] 1 participant 1 message May 2, 2015

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Stable branch DRM drivers Intel i915
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The patch below does not apply to the 4.0-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

Quoted 1 line

From 9da7d69357389ea63893434fe3b17b9fbc2c2d2d Mon Sep 17 00:00:00 2001

From: Daniel Vetter <[email protected]>
Date: Thu, 9 Apr 2015 16:44:15 +0200
Subject: [PATCH] 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 a93fad0f7fb8a3ff12e8814b630648f6d187954c

Author: Vandana Kannan <[email protected]>
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 <[email protected]>
Cc Ville Syrjälä <[email protected]>
Cc Ramalingam C <[email protected]>
Cc Rodrigo Vivi <[email protected]>
Cc Vandana Kannan <[email protected]>
Cc [email protected] (4.0+ only)
Reviewed-by Chris Wilson <[email protected]>
Tested-by Chris Wilson <[email protected]>
Signed-off-by Daniel Vetter <[email protected]>
Signed-off-by Jani Nikula <[email protected]>
drivers/gpu/drm/i915/intel_dp.c +15 -7
index b70e635ccaf4..5e60473d08fe 100644
@@ -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;