[02/15] thermal: sysfs: lock tz while on access to mode properties
diff mbox

Message ID 1464676296-5610-3-git-send-email-edubezval@gmail.com
State Changes Requested
Delegated to: Zhang Rui
Headers show

Commit Message

Eduardo Valentin May 31, 2016, 6:31 a.m. UTC
Serialized calls to tz.ops in user facing
sysfs handler mode_show()  and mode_store().

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(-)

Comments

Keerthy June 7, 2016, 9:08 a.m. UTC | #1
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

>
> 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;
>
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Keerthy June 7, 2016, 9:22 a.m. UTC | #2
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 <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;
>>
> --
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Zhang Rui June 22, 2016, 2:45 a.m. UTC | #3
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 <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;
> > > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-pm" 
> > in
> > the body of a message to majordomo@vger.kernel.org
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Patch
diff mbox

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;