From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keerthy Subject: Re: [PATCH 02/15] thermal: sysfs: lock tz while on access to mode properties Date: Tue, 7 Jun 2016 14:52:07 +0530 Message-ID: <5756923F.6010007@ti.com> References: <1464676296-5610-1-git-send-email-edubezval@gmail.com> <1464676296-5610-3-git-send-email-edubezval@gmail.com> <57568F08.2070307@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <57568F08.2070307@ti.com> Sender: linux-kernel-owner@vger.kernel.org To: Eduardo Valentin , Rui Zhang Cc: Linux PM , LKML , "R, Vignesh" List-Id: linux-pm@vger.kernel.org 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. Regards, Keerthy > > Regards, > Keerthy > >> >> Cc: Zhang Rui >> Cc: linux-pm@vger.kernel.org >> Cc: linux-kernel@vger.kernel.org >> Signed-off-by: Eduardo Valentin >> --- >> 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 majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html