From 3954e733ab0c9449443897f2669e17fff4471a0e Mon Sep 17 00:00:00 2001 From: Ramalingam C Date: Tue, 3 Mar 2015 12:11:46 +0530 Subject: [PATCH] drm/i915: Fixing mutex deadlock window at eDP DRRS In invalidate and flush functions of eDP DRRS, if deferred downclock work starts execution at a time window between acquiring the drrs mutex and cancellation of the deferred work (intel_edp_drrs_downclock_work), then deferred work will find drrs mutex locked and wait for the same. Meanwhile the function that acquired mutex drrs invalidate/flush will wait for the completion of the deferred work before releasing the mutex. Thats a deadlock. To avoid such deadlock scenario, this change cancels the deferred work before acquiring the mutex at invalidate and flush functions. Signed-off-by: Ramalingam C Reviewed-by: Rodrigo Vivi Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/intel_dp.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index d1141d37e205..0a57763e73fa 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -4966,12 +4966,13 @@ void intel_edp_drrs_invalidate(struct drm_device *dev, if (!dev_priv->drrs.dp) return; + cancel_delayed_work_sync(&dev_priv->drrs.work); + mutex_lock(&dev_priv->drrs.mutex); crtc = dp_to_dig_port(dev_priv->drrs.dp)->base.base.crtc; pipe = to_intel_crtc(crtc)->pipe; if (dev_priv->drrs.refresh_rate_type == DRRS_LOW_RR) { - cancel_delayed_work_sync(&dev_priv->drrs.work); intel_dp_set_drrs_state(dev_priv->dev, dev_priv->drrs.dp->attached_connector->panel. fixed_mode->vrefresh); @@ -5004,13 +5005,13 @@ void intel_edp_drrs_flush(struct drm_device *dev, if (!dev_priv->drrs.dp) return; + cancel_delayed_work_sync(&dev_priv->drrs.work); + mutex_lock(&dev_priv->drrs.mutex); 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; - cancel_delayed_work_sync(&dev_priv->drrs.work); - if (dev_priv->drrs.refresh_rate_type != DRRS_LOW_RR && !dev_priv->drrs.busy_frontbuffer_bits) schedule_delayed_work(&dev_priv->drrs.work, -- 2.20.1