On 二, 2016-06-07 at 14:52 +0530, Keerthy wrote: > > On Tuesday 07 June 2016 02:38 PM, Keerthy wrote: > > > > Hi Eduardo, > > > > On Tuesday 31 May 2016 12:01 PM, Eduardo Valentin wrote: > > > > > > Serialized calls to tz.ops in user facing > > > sysfs handler mode_show() and mode_store(). > > This seems to be causing a deadlock at boot time during the ending > > stages of boot: > > > > http://pastebin.ubuntu.com/17085291/ > > > > It took a while to git bisect on linux-next. > > > > Seems like you introduced new locking at the sysfs layer which > > causes > > this deadlock as the underlying code again tries to acquire the > > same > > tz->lock. > I confirm reverting this patch helps me boot on linux-next. This > patch > can be dropped as the lower layer functions are already acquiring tz- > >lock. > > Thanks Vignesh for reporting the deadlock. > the root cause of the deadlock is that some platform driver invokes thermal_zone_device_update() in .set_mode(), after mode changed.
If we wants to lock tz->ops->set_mode(), we should cleanup all the platform thermal drivers, and deliver a thermal_zone_device_update() in mode_store(), at the same time. thanks, rui > Regards, > Keerthy > > > > > > > Regards, > > Keerthy > > > > > > > > > > > Cc: Zhang Rui <[email protected]> > > > Cc: [email protected] > > > Cc: [email protected] > > > Signed-off-by: Eduardo Valentin <[email protected]> > > > --- > > > drivers/thermal/thermal_sysfs.c | 13 ++++++++++--- > > > 1 file changed, 10 insertions(+), 3 deletions(-) > > > > > > diff --git a/drivers/thermal/thermal_sysfs.c > > > b/drivers/thermal/thermal_sysfs.c > > > index ee983ca..1db2406 100644 > > > --- a/drivers/thermal/thermal_sysfs.c > > > +++ b/drivers/thermal/thermal_sysfs.c > > > @@ -62,7 +62,9 @@ mode_show(struct device *dev, struct > > > device_attribute *attr, char *buf) > > > if (!tz->ops->get_mode) > > > return -EPERM; > > > > > > + mutex_lock(&tz->lock); > > > result = tz->ops->get_mode(tz, &mode); > > > + mutex_unlock(&tz->lock); > > > if (result) > > > return result; > > > > > > @@ -75,17 +77,22 @@ mode_store(struct device *dev, struct > > > device_attribute *attr, > > > const char *buf, size_t count) > > > { > > > struct thermal_zone_device *tz = to_thermal_zone(dev); > > > + enum thermal_device_mode mode = THERMAL_DEVICE_DISABLED; > > > int result; > > > > > > if (!tz->ops->set_mode) > > > return -EPERM; > > > > > > if (!strncmp(buf, "enabled", sizeof("enabled") - 1)) > > > - result = tz->ops->set_mode(tz, THERMAL_DEVICE_ENABLED); > > > + mode = THERMAL_DEVICE_ENABLED; > > > else if (!strncmp(buf, "disabled", sizeof("disabled") - 1)) > > > - result = tz->ops->set_mode(tz, THERMAL_DEVICE_DISABLED); > > > + mode = THERMAL_DEVICE_DISABLED; > > > else > > > - result = -EINVAL; > > > + return -EINVAL; > > > + > > > + mutex_lock(&tz->lock); > > > + result = tz->ops->set_mode(tz, mode); > > > + mutex_unlock(&tz->lock); > > > > > > if (result) > > > return result; > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-pm" > > in > > the body of a message to [email protected] > > More majordomo info at http://vger.kernel.org/majordomo-info.html
