Re: [PATCH] x86/apic: Fix suspicious RCU usage in smp_trace_call_function_interrupt

[Thomas Gleixner]

On Thu, 15 Sep 2016, Wanpeng Li wrote:
> ---
>  arch/x86/include/asm/apic.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
> index 1243577..71c1fe2 100644
> --- a/arch/x86/include/asm/apic.h
> +++ b/arch/x86/include/asm/apic.h
> @@ -650,8 +650,8 @@ static inline void entering_ack_irq(void)
>  
>  static inline void ipi_entering_ack_irq(void)
>  {
> -     ack_APIC_irq();
>       irq_enter();
> +     ack_APIC_irq();
>  }

which makes ipi_entering_ack_irq() the same as entering_ack_irq() and
therefor pointless.

Looking further we have the same issue in exiting_ack_irq() where we call
ack_APIC_irq() after irq_exit().

Thanks,

        tglx