From a65e34c79c88895766ab1f8a5afa451eed26622b Mon Sep 17 00:00:00 2001 From: Keith Packard Date: Mon, 25 Jul 2011 10:04:56 -0700 Subject: [PATCH] drm/i915: Hold mode_config->mutex during hotplug processing Hotplug detection is a mode setting operation and must hold the struct_mutex or risk colliding with other mode setting operations. In particular, the display port hotplug function attempts to re-train the link if the monitor is supposed to be running when plugged back in. If that happens while mode setting is underway, the link will get scrambled, leaving it in an inconsistent state. This is a special case -- usually the driver mode setting entry points are covered by the upper level DRM code, but in this case the function is invoked as a work function not under the control of DRM. Signed-off-by: Keith Packard Cc: stable@kernel.org Reviewed-by: Jesse Barnes --- drivers/gpu/drm/i915/i915_irq.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index 3b03f85ea627..9da2a2c99953 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -306,6 +306,7 @@ static void i915_hotplug_work_func(struct work_struct *work) struct drm_mode_config *mode_config = &dev->mode_config; struct intel_encoder *encoder; + mutex_lock(&mode_config->mutex); DRM_DEBUG_KMS("running encoder hotplug functions\n"); list_for_each_entry(encoder, &mode_config->encoder_list, base.head) @@ -314,6 +315,8 @@ static void i915_hotplug_work_func(struct work_struct *work) /* Just fire off a uevent and let userspace tell us what to do */ drm_helper_hpd_irq_event(dev); + + mutex_unlock(&mode_config->mutex); } static void i915_handle_rps_change(struct drm_device *dev) -- 2.20.1