* [PATCH v5] PM / devfreq: Restart previous governor if new governor fails to start
@ 2019-03-11 10:06 Sibi Sankar
[not found] ` <CGME20190311100759epcas5p41fc634cd67a99b39cd25c4129e489c4c@epcms1p2>
0 siblings, 1 reply; 3+ messages in thread
From: Sibi Sankar @ 2019-03-11 10:06 UTC (permalink / raw)
To: myungjoo.ham, kyungmin.park
Cc: cw00.choi, linux-pm, linux-kernel, linux-arm-msm-owner,
Saravana Kannan, Sibi Sankar
From: Saravana Kannan <skannan@codeaurora.org>
If the new governor fails to start, switch back to old governor so that the
devfreq state is not left in some weird limbo.
[Mjungjoo: assume fatal on revert failure and set df->governor to NULL]
Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
---
V5:
* assume fatal on revert failure and set df->governor to NULL
V4:
* Removed prev_governor check.
V3:
* Fix NULL deref for real this time.
* Addressed some style preferences.
V2:
* Fixed typo in commit text
* Fixed potential NULL deref
drivers/devfreq/devfreq.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 428a1de81008..37490235ec34 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -1124,7 +1124,7 @@ 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)
@@ -1153,12 +1153,24 @@ 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);
+ df->governor = prev_governor;
+ strncpy(df->governor_name, prev_governor->name,
+ DEVFREQ_NAME_LEN);
+ ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
+ if (ret) {
+ dev_warn(dev,
+ "%s: reverting to Governor %s failed (%d)\n",
+ __func__, df->governor_name, ret);
+ df->governor = NULL;
+ }
+ }
out:
mutex_unlock(&devfreq_list_lock);
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
^ permalink raw reply related [flat|nested] 3+ messages in thread
* RE: [PATCH v5] PM / devfreq: Restart previous governor if new governor fails to start
[not found] ` <CGME20190311100759epcas5p41fc634cd67a99b39cd25c4129e489c4c@epcms1p2>
@ 2019-03-12 7:17 ` MyungJoo Ham
2019-03-13 6:01 ` Sibi Sankar
0 siblings, 1 reply; 3+ messages in thread
From: MyungJoo Ham @ 2019-03-12 7:17 UTC (permalink / raw)
To: Chanwoo Choi, Sibi Sankar
Cc: Kyungmin Park, linux-pm, linux-kernel, linux-arm-msm-owner,
Saravana Kannan
>From: Saravana Kannan <skannan@codeaurora.org>
>
>If the new governor fails to start, switch back to old governor so that the
>devfreq state is not left in some weird limbo.
>
>[Mjungjoo: assume fatal on revert failure and set df->governor to NULL]
>Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
>Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
>Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
I'll modify WARN->ERROR for the case when it's fatal:
>+ if (ret) {
>+ dev_warn(dev,
>+ "%s: reverting to Governor %s failed (%d)\n",
>+ __func__, df->governor_name, ret);
>+ df->governor = NULL;
>+ }
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
>---
>V5:
>* assume fatal on revert failure and set df->governor to NULL
>
>V4:
>* Removed prev_governor check.
>
>V3:
>* Fix NULL deref for real this time.
>* Addressed some style preferences.
>
>V2:
>* Fixed typo in commit text
>* Fixed potential NULL deref
>
> drivers/devfreq/devfreq.c | 16 ++++++++++++++--
> 1 file changed, 14 insertions(+), 2 deletions(-)
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v5] PM / devfreq: Restart previous governor if new governor fails to start
2019-03-12 7:17 ` MyungJoo Ham
@ 2019-03-13 6:01 ` Sibi Sankar
0 siblings, 0 replies; 3+ messages in thread
From: Sibi Sankar @ 2019-03-13 6:01 UTC (permalink / raw)
To: myungjoo.ham
Cc: Chanwoo Choi, Kyungmin Park, linux-pm, linux-kernel,
linux-arm-msm-owner, Saravana Kannan
On 2019-03-12 12:47, MyungJoo Ham wrote:
>> From: Saravana Kannan <skannan@codeaurora.org>
>>
>> If the new governor fails to start, switch back to old governor so
>> that the
>> devfreq state is not left in some weird limbo.
>>
>> [Mjungjoo: assume fatal on revert failure and set df->governor to
>> NULL]
>> Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
>> Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
>> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
>
> I'll modify WARN->ERROR for the case when it's fatal:
Sure, thanks.
>
>> + if (ret) {
>> + dev_warn(dev,
>> + "%s: reverting to Governor %s failed (%d)\n",
>> + __func__, df->governor_name, ret);
>> + df->governor = NULL;
>> + }
>
> Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
>
>
>> ---
>> V5:
>> * assume fatal on revert failure and set df->governor to NULL
>>
>> V4:
>> * Removed prev_governor check.
>>
>> V3:
>> * Fix NULL deref for real this time.
>> * Addressed some style preferences.
>>
>> V2:
>> * Fixed typo in commit text
>> * Fixed potential NULL deref
>>
>> drivers/devfreq/devfreq.c | 16 ++++++++++++++--
>> 1 file changed, 14 insertions(+), 2 deletions(-)
>>
--
-- Sibi Sankar --
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-03-11 10:06 [PATCH v5] PM / devfreq: Restart previous governor if new governor fails to start Sibi Sankar
[not found] ` <CGME20190311100759epcas5p41fc634cd67a99b39cd25c4129e489c4c@epcms1p2>
2019-03-12 7:17 ` MyungJoo Ham
2019-03-13 6:01 ` Sibi Sankar
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