linux-kernel - Re: [PATCH] base: power: domain: Replace mdelay with msleep

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Message-ID: <20180126102604.GB13775@amd>
Date:   Fri, 26 Jan 2018 11:26:04 +0100
From:   Pavel Machek <pavel@....cz>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     rjw@...ysocki.net, khilman@...nel.org, ulf.hansson@...aro.org,
        len.brown@...el.com, gregkh@...uxfoundation.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] base: power: domain: Replace mdelay with msleep

On Fri 2018-01-26 16:38:19, Jia-Ju Bai wrote:
> After checking all possible call chains to genpd_dev_pm_detach() and
> genpd_dev_pm_attach() here,
> my tool finds that these functions are never called in atomic context,
> namely never in an interrupt handler or holding a spinlock.
> Thus mdelay can be replaced with msleep to avoid busy wait.
> 
> This is found by a static analysis tool named DCNS written by
myself.

Well, cond_resched() just after msleep certainly looks like that.

Did the patch receive any testing?

> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
> ---
>  drivers/base/power/domain.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 0c80bea..f84ac72 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off)
>  		if (ret != -EAGAIN)
>  			break;
>  
> -		mdelay(i);
> +		msleep(i);
>  		cond_resched();
>  	}
>  
> @@ -2231,7 +2231,7 @@ int genpd_dev_pm_attach(struct device *dev)
>  		if (ret != -EAGAIN)
>  			break;
>  
> -		mdelay(i);
> +		msleep(i);
>  		cond_resched();
>  	}
>  	mutex_unlock(&gpd_list_lock);

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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