linux-kernel - Re: [PATCH v14 2/3] trace,x86: Introduce entering/exiting

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Date:	Thu, 06 Jun 2013 14:26:13 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Seiji Aguchi <seiji.aguchi@....com>
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, tglx@...utronix.de,
	mingo@...e.hu, bp@...en8.de, linux-edac@...r.kernel.org,
	tony.luck@...el.com, dle-develop@...ts.sourceforge.net,
	tomoki.sekiyama@....com
Subject: Re: [PATCH v14 2/3] trace,x86: Introduce entering/exiting_irq()

On Thu, 2013-06-06 at 11:23 -0400, Seiji Aguchi wrote:
> ---
>  arch/x86/include/asm/apic.h |   27 +++++++++++++++++++++++++++
>  1 files changed, 27 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
> index 3388034..f8119b5 100644
> --- a/arch/x86/include/asm/apic.h
> +++ b/arch/x86/include/asm/apic.h
> @@ -12,6 +12,7 @@
>  #include <asm/fixmap.h>
>  #include <asm/mpspec.h>
>  #include <asm/msr.h>
> +#include <asm/idle.h>
>  
>  #define ARCH_APICTIMER_STOPS_ON_C3	1
>  
> @@ -687,5 +688,31 @@ extern int default_check_phys_apicid_present(int phys_apicid);
>  #endif
>  
>  #endif /* CONFIG_X86_LOCAL_APIC */
> +extern void irq_enter(void);
> +extern void irq_exit(void);
> +
> +static inline void entering_irq(void)
> +{
> +	irq_enter();
> +	exit_idle();
> +}
> +
> +static inline void entering_ack_irq(void)
> +{
> +	ack_APIC_irq();
> +	entering_irq();
> +}
> +
> +static inline void exiting_irq(void)
> +{
> +	irq_exit();
> +}
> +
> +static inline void exiting_ack_irq(void)
> +{
> +	irq_exit();
> +	/* Ack only at the end to avoid potential reentry */
> +	ack_APIC_irq();
> +}
>  
>  #endif /* _ASM_X86_APIC_H */

I think it also makes sense to use these in this patch as well. That is,
go ahead and make the changes likes this:

@@ -919,17 +919,14 @@ void __irq_entry smp_apic_timer_interrupt(struct pt_regs *regs)
 	/*
 	 * NOTE! We'd better ACK the irq immediately,
 	 * because timer handling can be slow.
-	 */
-	ack_APIC_irq();
-	/*
+	 *
 	 * update_process_times() expects us to have done irq_enter().
 	 * Besides, if we don't timer interrupts ignore the global
 	 * interrupt lock, which is the WrongThing (tm) to do.
 	 */
-	irq_enter();
-	exit_idle();
+	entering_ack_irq();
 	local_apic_timer_interrupt();
-	irq_exit();
+	exiting_irq();
 
 	set_irq_regs(old_regs);
 }

And do that with all the interrupts.

I think this is getting close for adding to 3.11 queue.

-- Steve


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