| Message ID | 20190311100630.12952-1-sibis@codeaurora.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | [v5] PM / devfreq: Restart previous governor if new governor fails to start | expand |
>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(-) >
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(-) >>
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);