Re: [Xen-ia64-devel] [PATCH] fix I&D cache incoherency after vcpu migration

[Alex Williamson <alex.williamson@xxxxxx>]

On Tue, 2007-02-13 at 21:15 +0900, Kouya SHIMURA wrote:
> +static void flush_cache_for_context_switch(struct vcpu *next)
> +{
> +       extern cpumask_t cpu_cache_coherent_map;
> +       int cpu = smp_processor_id();
> +
> +       if (is_idle_vcpu(next) ||
> +           __test_and_clear_bit(cpu, &next->arch.cache_coherent_map))
> { 

Hi Kouya,

   Isn't this racey?  Why use the non-atomic __test_and_clear_bit() here
rather than the atomic version?  Thanks,

        Alex

-- 
Alex Williamson                             HP Open Source & Linux Org.


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