linux-kernel - Re: [PATCH 1/1] thermal: fix cpu_cooling max

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Date:	Thu, 02 Jan 2014 12:02:30 +0800
From:	Zhang Rui <rui.zhang@...el.com>
To:	Eduardo Valentin <eduardo.valentin@...com>
Cc:	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] thermal: fix cpu_cooling max_level behavior

On Fri, 2013-12-06 at 09:52 -0400, Eduardo Valentin wrote:
> On 13-11-2013 14:11, Eduardo Valentin wrote:
> > As per Documentation/thermal/sysfs-api.txt, max_level
> > is an index, not a counter. Thus, in case a CPU has
> > 3 valid frequencies, max_level is expected to be 2, for instance.
> > 
> > The current code makes max_level == number of valid frequencies,
> > which is bogus. This patch fix the cpu_cooling device by
> > ranging max_level properly.
> > 
good catch.
> > Reported-by: Carlos Hernandez <ceh@...com>
> > Signed-off-by: Eduardo Valentin <eduardo.valentin@...com>
> 
> Rui,
> 
> Can you please consider pushing this fix?
> 
applied.

> > ---
> >  drivers/thermal/cpu_cooling.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
> > index d179028..d0f8f8b5 100644
> > --- a/drivers/thermal/cpu_cooling.c
> > +++ b/drivers/thermal/cpu_cooling.c
> > @@ -173,6 +173,8 @@ static int get_property(unsigned int cpu, unsigned long input,
> >  		freq = table[i].frequency;
> >  		max_level++;
> >  	}
> > +	/* max_level is an index, not a counter */
> > +	max_level--;
> >
I think we should check the max_level first, like the patch I attached
below.

thanks,
rui

>From a116776f7b6052599df0c67db29c30ea9d69d7ee Mon Sep 17 00:00:00 2001
From: Zhang Rui <rui.zhang@...el.com>
Date: Thu, 2 Jan 2014 11:57:48 +0800
Subject: [PATCH] Thermal cpu cooling: return error if no valid cpu frequency
 entry

Signed-off-by: Zhang Rui <rui.zhang@...el.com>
---
 drivers/thermal/cpu_cooling.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index cc556a8..bb486b4 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -173,6 +173,11 @@ static int get_property(unsigned int cpu, unsigned long input,
 		freq = table[i].frequency;
 		max_level++;
 	}
+
+	/* No valid cpu frequency entry */
+	if (max_level == 0)
+		return -EINVAL;
+
 	/* max_level is an index, not a counter */
 	max_level--;
 
-- 
1.7.9.5



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