linux-kernel - Re: [PATCH] cpuidle: fix broadcast control when broadcast can not be entered

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Message-ID: <alpine.DEB.2.20.1709010944490.1857@nanos>
Date:   Fri, 1 Sep 2017 09:44:56 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Nicholas Piggin <npiggin@...il.com>
cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpuidle: fix broadcast control when broadcast can not
 be entered

On Fri, 1 Sep 2017, Nicholas Piggin wrote:

> When failing to enter broadcast timer mode for an idle state that
> requires it, a new state is selected that does not require broadcast,
> but the broadcast variable remains set. This causes
> tick_broadcast_exit to be called despite not having entered broadcast
> mode.
> 
> This causes the WARN_ON_ONCE(!irqs_disabled()) to trigger in some
> cases. It does not appear to cause problems for code today, but seems
> to violate the interface so should be fixed.
> 
> Signed-off-by: Nicholas Piggin <npiggin@...il.com>

Reviewed-by: Thomas Gleixner <tglx@...utronix.de>

> ---
>  drivers/cpuidle/cpuidle.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
> index 60bb64f4329d..4453e27f855e 100644
> --- a/drivers/cpuidle/cpuidle.c
> +++ b/drivers/cpuidle/cpuidle.c
> @@ -208,6 +208,7 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
>  			return -EBUSY;
>  		}
>  		target_state = &drv->states[index];
> +		broadcast = false;
>  	}
>  
>  	/* Take note of the planned idle state. */
> -- 
> 2.13.3
> 
>