linux-kernel - Re: [lm-sensors] [PATCH 3/3] hwmon: (jc42) do not allow writing to locked registers

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Date:	Wed, 16 Feb 2011 08:15:19 -0800
From:	Guenter Roeck <guenter.roeck@...csson.com>
To:	Clemens Ladisch <clemens@...isch.de>
CC:	Jean Delvare <khali@...ux-fr.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"lm-sensors@...sensors.org" <lm-sensors@...sensors.org>
Subject: Re: [lm-sensors] [PATCH 3/3] hwmon: (jc42) do not allow writing to
 locked registers

On Wed, Feb 16, 2011 at 10:38:38AM -0500, Clemens Ladisch wrote:
> Guenter Roeck wrote:
> > On Wed, Feb 16, 2011 at 10:11:35AM -0500, Clemens Ladisch wrote:
> > > Guenter Roeck wrote:
> > > > On Wed, Feb 16, 2011 at 08:02:38AM -0500, Clemens Ladisch wrote:
> > > > > +		readonly = config & JC42_CFG_TCRIT_LOCK;
> > > > 
> > > > You are assigning a non-bool to a bool. I can see that recent C compilers
> > > > do the right thing, but I am not sure if that is always the case.
> > > > So I would prefer
> > > > 		readonly = !!(config & JC42_CFG_TCRIT_LOCK);
> > > > 
> > > > Same for the assignments below. I can make that change if you are ok with it.
> > > 
> > > I cannot imagine how a compiler could get this wrong even if it tried
> > > to, but if you think so, go ahead.  :)
> > 
> > I don't know. Maybe I am just paranoid. Using !! is how I usually see it done.
> 
> Usually, !! is used to convert non-zero to the _integer_ 1.  With
> a compiler that implements bool, this conversion is already implied.
> On older compilers, someone might be tempted to do "#define bool int",
> but this is not an issue with the compilers required by Linux.
> 
I looked up other drivers, and they do the same, so I'll declare it safe 
and apply your patch without modification.

Thanks,
Guenter
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