linux-kernel - Re: [lm-sensors] [PATCH] hwmon: coretemp: use list instead of fixed size array for temp data

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Message-ID: <20120503100409.GA6971@otc-wbsnb-06>
Date:	Thu, 3 May 2012 13:04:09 +0300
From:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:	"R, Durgadoss" <durgadoss.r@...el.com>
Cc:	"Yu, Fenghua" <fenghua.yu@...el.com>,
	Guenter Roeck <guenter.roeck@...csson.com>,
	Andi Kleen <ak@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"lm-sensors@...sensors.org" <lm-sensors@...sensors.org>
Subject: Re: [lm-sensors] [PATCH] hwmon: coretemp: use list instead of fixed
 size array for temp data

On Thu, May 03, 2012 at 05:29:43AM +0000, R, Durgadoss wrote:
> > @@ -707,14 +787,12 @@ static void __cpuinit put_core_offline(unsigned int cpu)
> > 
> >  	pdata = platform_get_drvdata(pdev);
> > 
> > -	indx = TO_ATTR_NO(cpu);
> > -
> > -	/* The core id is too big, just return */
> > -	if (indx > MAX_CORE_DATA - 1)
> > -		return;
> > +	attr_no = TO_ATTR_NO(cpu);
> > 
> > -	if (pdata->core_data[indx] && pdata->core_data[indx]->cpu == cpu)
> > -		coretemp_remove_core(pdata, &pdev->dev, indx);
> > +	tdata = get_temp_data(pdata, attr_no);
> > +	if (tdata->cpu == cpu)
> 
> The get_temp_data can return a NULL. So, you might want to do,
> if (tdata && tdata->cpu == cpu) to avoid a potential NULL ptr crash.

Good catch, thanks.

> In general, why are we using spin_locks instead of mutex_locks,
> for list manipulations .. ?

I don't think it matters here. Contention is low and nobody sleeps, but
okay, I'll change it to mutex.

-- 
 Kirill A. Shutemov

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