linux-kernel - Re: [Patch-next] Trival fixes in thermal_throttle_add

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Message-ID: <20100831090725.5d83eedb@hyperion.delvare>
Date:	Tue, 31 Aug 2010 09:07:25 +0200
From:	Jean Delvare <khali@...ux-fr.org>
To:	Fenghua Yu <fenghua.yu@...el.com>
Cc:	Jin Dongming <jin.dongming@...css.fujitsu.com>,
	"Brown, Len" <len.brown@...el.com>,
	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
	"H. Peter Anvin" <hpa@...ux.jf.intel.com>,
	LKLM <linux-kernel@...r.kernel.org>,
	"lm-sensors@...sensors.org" <lm-sensors@...sensors.org>,
	mingo Redhat <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [Patch-next] Trival fixes in thermal_throttle_add_dev().

Hi Fenghua,

On Mon, 30 Aug 2010 18:02:52 -0700, Fenghua Yu wrote:
> On Mon, Aug 30, 2010 at 05:55:48PM -0700, Jin Dongming wrote:
> > This patch fixed the following two problems.
> >   1. When the feature PTS is not supported by CPU, the sysfile
> >      package_power_limit_count for package should not be generated.
> >   2. No matter whether a sysfile is failed to be created or not,
> >      the next one will be created.
> > 
> > As the resolving methods:
> >   1. Add missing { and } after checking PTS feature.
> >   2. Fix the error handling.
> > 
> > Signed-off-by: Jin Dongming <jin.dongming@...css.fujitsu.com>
> > Reviewed-by: Fenghua Yu <fenghua.yu@...tel.com>
> > ---
> >  arch/x86/kernel/cpu/mcheck/therm_throt.c |   15 ++++++++++++++-
> >  1 files changed, 14 insertions(+), 1 deletions(-)
> > 
> > diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c
> > index d9368ee..79d563a 100644
> > --- a/arch/x86/kernel/cpu/mcheck/therm_throt.c
> > +++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c
> > @@ -216,14 +216,27 @@ static __cpuinit int thermal_throttle_add_dev(struct sys_device *sys_dev,
> >  		err = sysfs_add_file_to_group(&sys_dev->kobj,
> >  					      &attr_core_power_limit_count.attr,
> >  					      thermal_attr_group.name);
> > -	if (cpu_has(c, X86_FEATURE_PTS))
> > +	if (err)
> > +		goto error;
> > +
> > +	if (cpu_has(c, X86_FEATURE_PTS)) {
> >  		err = sysfs_add_file_to_group(&sys_dev->kobj,
> >  					      &attr_package_throttle_count.attr,
> >  					      thermal_attr_group.name);
> > +		if (err)
> > +			goto error;
> > +
> >  		if (cpu_has(c, X86_FEATURE_PLN))
> >  			err = sysfs_add_file_to_group(&sys_dev->kobj,
> >  					&attr_package_power_limit_count.attr,
> >  					thermal_attr_group.name);
> > +		if (err)
> > +			goto error;
> > +	}
> > +
> > +	return 0;
> > +error:
> > +	sysfs_remove_group(&sys_dev->kobj, &thermal_attr_group);
> >  
> >  	return err;
> >  }
> 
> This fix is incorrect. In this patch, a previous error prevents from adding any
> further devices. There shouldn't be such dependency among the devices.

I don't quite follow you. Did you mean to write that a previous error
prevents from creating further _attributes_ for the same device? This
would be true.

Now I don't think this is a problem because 1* such errors should never
happen anyway and 2* if they do happen then further attempts to create
the other attributes are unlikely to succeed either.

-- 
Jean Delvare
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