From 9da7d69357389ea63893434fe3b17b9fbc2c2d2d Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Thu, 9 Apr 2015 16:44:15 +0200 Subject: [PATCH] drm/i915: Fix locking in DRRS flush/invalidate hooks MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 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 Cc: Ville Syrjälä Cc: Ramalingam C Cc: Rodrigo Vivi Cc: Vandana Kannan Cc: stable@vger.kernel.org (4.0+ only) Reviewed-by: Chris Wilson Tested-by: Chris Wilson Signed-off-by: Daniel Vetter Signed-off-by: Jani Nikula --- drivers/gpu/drm/i915/intel_dp.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index b70e635ccaf4..5e60473d08fe 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -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; -- 2.20.1