Commit a167b1e1 authored Sep 04, 2018 by Chris Wilson

drm/i915: Pull intel_uncore_arm_unclaimed_mmio_detection() under the spinlock

Elsewhere we manipulate uncore.unclaimed_mmio_check and
i915_param.mmio_debug under the irq lock (e.g. preserving the current
value across a user forcewake grab), but do not protect the manipulation
inside intel_uncore_arm_unclaimed_mmio_detection() from concurrent
access, even from itself. This is an issue as we do call
arm_unclaimed_mmio_detection from multiple threads without coordination.

Suggested-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intelcom>
Link: https://patchwork.freedesktop.org/patch/msgid/20180904131207.17563-1-chris@chris-wilson.co.uk

parent b212f0a4

drivers/gpu/drm/i915/intel_uncore.c

+10 −3

Original line number	Diff line number	Diff line
		@@ -2283,8 +2283,12 @@ bool intel_uncore_unclaimed_mmio(struct drm_i915_private *dev_priv)
		bool
		intel_uncore_arm_unclaimed_mmio_detection(struct drm_i915_private *dev_priv)
		{
		bool ret = false;

		spin_lock_irq(&dev_priv->uncore.lock);

		if (unlikely(dev_priv->uncore.unclaimed_mmio_check <= 0))
		return false;
		goto out;

		if (unlikely(intel_uncore_unclaimed_mmio(dev_priv))) {
		if (!i915_modparams.mmio_debug) {
		@@ -2294,10 +2298,13 @@ intel_uncore_arm_unclaimed_mmio_detection(struct drm_i915_private *dev_priv)
		i915_modparams.mmio_debug++;
		}
		dev_priv->uncore.unclaimed_mmio_check--;
		return true;
		ret = true;
		}

		return false;
		out:
		spin_unlock_irq(&dev_priv->uncore.lock);

		return ret;
		}

		static enum forcewake_domains