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

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Date:	Thu, 6 Jun 2013 20:51:07 +0000
From:	Seiji Aguchi <seiji.aguchi@....com>
To:	Steven Rostedt <rostedt@...dmis.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"hpa@...or.com" <hpa@...or.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"mingo@...e.hu" <mingo@...e.hu>, "bp@...en8.de" <bp@...en8.de>,
	"linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
	"tony.luck@...el.com" <tony.luck@...el.com>,
	"dle-develop@...ts.sourceforge.net" 
	<dle-develop@...ts.sourceforge.net>,
	Tomoki Sekiyama <tomoki.sekiyama@....com>
Subject: RE: [PATCH v14 2/3] trace,x86: Introduce entering/exiting_irq()



> -----Original Message-----
> From: Steven Rostedt [mailto:rostedt@...dmis.org]
> Sent: Thursday, June 06, 2013 2:26 PM
> To: Seiji Aguchi
> 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
> 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.

OK. Will do.

Seiji

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