linux-kernel - Re: [PATCH v2 3/5] sched,idle: Clear polling before descheduling the idle thread

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Message-ID: <20140604173655.GK13930@laptop.programming.kicks-ass.net>
Date:	Wed, 4 Jun 2014 19:36:55 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	umgwanakikbuti@...il.com, mingo@...nel.org, tglx@...utronix.de,
	nicolas.pitre@...aro.org, daniel.lezcano@...aro.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/5] sched,idle: Clear polling before descheduling the
 idle thread

On Wed, Jun 04, 2014 at 10:31:16AM -0700, Andy Lutomirski wrote:
> @@ -218,6 +234,15 @@ static void cpu_idle_loop(void)
>  		 */
>  		preempt_set_need_resched();
>  		tick_nohz_idle_exit();
> +		__current_clr_polling();
> +
> +		/*
> +		 * We promise to reschedule if need_resched is set while
> +		 * polling is set.  That means that clearing polling
> +		 * needs to be visible before rescheduling.
> +		 */
> +		smp_mb__after_clear_bit();
> +
>  		schedule_preempt_disabled();
>  	}
>  }

I recently renamed those barriers, its now called:

  smp_mb__after_atomic();

It'll still compile with the old names, and even work, but you'll get
__deprecated warns and horrid code generation.

I'll fix up when applying these patches, no need to resend.

Thanks!
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