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Date: Fri, 4 Jan 2013 08:51:13 -0800
From: jacob pan <jacob.jun.pan@linux.intel.com>
To: Joe Perches <joe@perches.com>
Cc: Linux PM <linux-pm@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        Rafael Wysocki <rafael.j.wysocki@intel.com>,
        Len Brown <len.brown@intel.com>, Thomas Gleixner <tglx@linutronix.de>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@elte.hu>,
        Zhang Rui <rui.zhang@intel.com>, Rob Landley <rob@landley.net>,
        Arjan van de Ven <arjan@linux.intel.com>,
        Paul McKenney <paulmck@linux.vnet.ibm.com>
Subject: Re: [PATCH v5 3/3] PM: Introduce Intel PowerClamp Driver
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On Thu, 03 Jan 2013 19:51:04 -0800
Joe Perches <joe@perches.com> wrote:

> On Thu, 2013-01-03 at 07:10 -0800, Jacob Pan wrote:
> > Intel PowerClamp driver performs synchronized idle injection across
> > all online CPUs. The goal is to maintain a given package level
> > C-state ratio.
> 
> []
> 
> > +static int window_size_set(const char *arg, const struct
> > kernel_param *kp) +{
> > +	int ret = 0;
> > +	unsigned long new_window_size;
> > +
> > +	ret = kstrtoul(arg, 10, &new_window_size);
> > +	if (ret)
> > +		goto exit_win;
> > +	if (new_window_size > 10 || new_window_size < 2) {
> > +		pr_err("Invalid window size %lu, between 2-10\n",
> > +			new_window_size);
> > +		ret = -EINVAL;
> > +	}
> > +
> > +	window_size = new_window_size;
> 
> Possible assignment of known invalid windows size?
> Maybe you should add
> 	goto exit;
> after
> 	ret = -EINVAL;
> 
> or add
> 	new_window_size = clamp(new_window_size, 2ul, 10ul);
Good catch. The window size range 2-10 is somewhat arbitrary, greater
than 10 should also work just not recommended. I will reword that. But
it is good to clamp it as you suggested, i will do that for the
duration parameter also.

Thanks,

Jacob