Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:
> 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@xxxxxxxxx>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_uncore.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index 05f0cda18501..3ad302c66254 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -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;
Patchbot didn't see how the future will unfold. I did.
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intelcom>
> }
>
> static enum forcewake_domains
> --
> 2.19.0.rc1
>
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