Re: [PATCH 02/15] thermal: sysfs: lock tz while on access to mode properties
From: Keerthy <hidden>
Date: 2016-06-07 09:08:32
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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. Regards, Keerthy
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Cc: Zhang Rui <rui.zhang@intel.com> Cc: linux-pm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Eduardo Valentin <edubezval@gmail.com> --- 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;