Re: [PATCH v2 1/3] x86/entry/64: Refactor IRQ stacks and make them NMI-safe

[Andy Shevchenko]

On Sat, Jul 25, 2015 at 8:57 AM, Andy Lutomirski <luto@xxxxxxxxxx> wrote:
> This will allow IRQ stacks to nest inside NMIs or similar entries
> that can happen during IRQ stack setup or teardown.
>
> The Xen code here has a confusing comment.
>
> The new macros won't work correctly if they're invoked with IRQs on.
> Add a check under CONFIG_DEBUG_ENTRY to detect that.
>

> +/*
> + * Enters the IRQ stack if we're not already using it.  NMI-safe.  Clobbers
> + * flags and puts old RSP into old_rsp, and leaves all other GPRs alone.
> + * Requires kernel GSBASE.
> + *
> + * The invariant is that, if irq_count != 1, then the IRQ stack is in use.
> + */

I might be wrong, but shouldn't be this read as 'if irq_count != -1' ?

-- 
With Best Regards,
Andy Shevchenko
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