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From: Chanwoo Choi <cw00.choi@samsung.com>
To: Saravana Kannan <skannan@codeaurora.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	MyungJoo Ham <myungjoo.ham@samsung.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] PM / devfreq: Restart previous governor if new governor fails to start
Date: Thu, 27 Oct 2016 09:06:00 +0900	[thread overview]
Message-ID: <de0f8010-31b2-8cec-f793-393c2199f44d@samsung.com> (raw)
In-Reply-To: <1477509425-16936-1-git-send-email-skannan@codeaurora.org>

Hi,

On 2016년 10월 27일 04:17, Saravana Kannan wrote:
> If the new governor fails to start, switch back to old governor so that the
> devfreq state is not left in some weird limbo.
> 
> Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
> ---
> * Fix NULL deref for real this time.
> * Addressed some style preferences.
> 
>  drivers/devfreq/devfreq.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index bf3ea76..77c41a5 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -919,7 +919,7 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
>  	struct devfreq *df = to_devfreq(dev);
>  	int ret;
>  	char str_governor[DEVFREQ_NAME_LEN + 1];
> -	struct devfreq_governor *governor;
> +	const struct devfreq_governor *governor, *prev_governor;
>  
>  	ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
>  	if (ret != 1)
> @@ -944,12 +944,21 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
>  			goto out;
>  		}
>  	}
> +	prev_governor = df->governor;
>  	df->governor = governor;
>  	strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
>  	ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
> -	if (ret)
> +	if (ret) {
>  		dev_warn(dev, "%s: Governor %s not started(%d)\n",
>  			 __func__, df->governor->name, ret);
> +		if (prev_governor) {

I think that prev_governor is always set. You don't need to check it.
Why do check it?

> +			df->governor = prev_governor;
> +			strncpy(df->governor_name, prev_governor->name,
> +				DEVFREQ_NAME_LEN);
> +			df->governor->event_handler(df, DEVFREQ_GOV_START,
> +						    NULL);
> +		}
> +	}
>  out:
>  	mutex_unlock(&devfreq_list_lock);
>  
> 

-- 
Best Regards,
Chanwoo Choi

  reply	other threads:[~2016-10-27  0:06 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20161026191715epcas1p311c2c626563a736e14c83fb0504c099e@epcas1p3.samsung.com>
2016-10-26 19:17 ` Saravana Kannan
2016-10-27  0:06   ` Chanwoo Choi [this message]
2016-11-07 18:57     ` Saravana Kannan
2016-11-08  9:02       ` Chanwoo Choi
2016-11-08 20:52         ` Saravana Kannan
2016-11-09  1:33           ` Chanwoo Choi
2016-11-09  2:36             ` Chanwoo Choi
2016-11-09  2:38               ` Chanwoo Choi
2016-11-09 20:34                 ` Saravana Kannan
2016-11-10  0:10                   ` Chanwoo Choi
2016-11-11 23:25                     ` Saravana Kannan
2016-11-12  2:17                       ` Chanwoo Choi
2016-11-12  2:18                         ` Chanwoo Choi
2018-12-07 20:29                     ` Saravana Kannan
2018-12-11  5:35                       ` Chanwoo Choi
     [not found]                       ` <CGME20161026191715epcas1p311c2c626563a736e14c83fb0504c099e@epcms1p3>
2018-12-11  7:18                         ` MyungJoo Ham

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