[Intel-gfx] [PATCH 2/3] drm/i915: close PM interrupt masking races in the rps work func

[Daniel Vetter]

On Sun, Sep 04, 2011 at 09:38:56PM +0000, Ben Widawsky wrote:
> Oops, you're totally right, I think I meant:
> -       I915_WRITE(GEN6_PMIMR, pm_imr & ~pm_iir);
> +       I915_WRITE(GEN6_PMIMR, dev_priv->pm_iir);

Imo still racy without the irqsafe rps_lock around it. gcc is free to
compile that into a separate load and store which the irq handler can get
in between and change dev_priv->pm_iir and PMIMR. The race is now only one
instruction wide, though ;-)
-Daniel
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
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