From: Saravana Kannan <skannan@codeaurora.org>
To: Chanwoo Choi <cw00.choi@samsung.com>
Cc: "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: Mon, 07 Nov 2016 10:57:02 -0800 [thread overview]
Message-ID: <5820CE7E.40802@codeaurora.org> (raw)
In-Reply-To: <de0f8010-31b2-8cec-f793-393c2199f44d@samsung.com>
On 10/26/2016 05:06 PM, Chanwoo Choi wrote:
> 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?
Not true. Even higher up in this function, we check if df->governor !=
NULL. Simple example would be that the default governor passed in while
adding the device isn't compiled in.
Thanks,
Saravana
--
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2016-11-07 19:04 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
2016-11-07 18:57 ` Saravana Kannan [this message]
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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