From: Saravana Kannan <skan...@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 <si...@codeaurora.org>
Signed-off-by: Saravana Kannan <skan...@codeaurora.org>
Reviewed-by: Chanwoo Choi <cw00.c...@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);
--
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