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SubjectRe: [PATCH 10/13] xen/pvticket: allow interrupts to be enabled while blocking
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On Thu, 2011-09-01 at 17:55 -0700, Jeremy Fitzhardinge wrote:
> + /* Make sure an interrupt handler can't upset things in a
> + partially setup state. */
> local_irq_save(flags);
>
> + /*
> + * We don't really care if we're overwriting some other
> + * (lock,want) pair, as that would mean that we're currently
> + * in an interrupt context, and the outer context had
> + * interrupts enabled. That has already kicked the VCPU out
> + * of xen_poll_irq(), so it will just return spuriously and
> + * retry with newly setup (lock,want).
> + *
> + * The ordering protocol on this is that the "lock" pointer
> + * may only be set non-NULL if the "want" ticket is correct.
> + * If we're updating "want", we must first clear "lock".
> + */
> + w->lock = NULL;

I mean, I don't much care about Xen code, but that's two different
comment styles.


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