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
next prev parent 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 ` [PATCH v3] PM / devfreq: Restart previous governor if new governor fails to start 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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