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Date: Mon, 1 Aug 2011 14:29:46 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Christian Lamparter <chunkeey@googlemail.com>
Cc: =?ISO-8859-1?Q?=C9ric?= Piel <eric.piel@tremplin-utc.net>,
        Matthew Garrett <mjg@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
        platform-driver-x86@vger.kernel.org
Subject: Re: [PATCH 01/10] lis3lv02d: avoid divide by zero due to unchecked
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On Mon, 1 Aug 2011 23:11:17 +0200
Christian Lamparter <chunkeey@googlemail.com> wrote:

> On Monday, August 01, 2011 10:29:06 PM Andrew Morton wrote:
> > On Mon, 25 Jul 2011 17:16:23 +0200
> > __ric Piel <eric.piel@tremplin-utc.net> wrote:
> > 
> > > +static int lis3lv02d_get_pwron_wait(struct lis3lv02d *lis3)
> > > +{
> > > +	int div = lis3lv02d_get_odr();
> > > +
> > > +	if (WARN_ONCE(div == 0, "device returned spurious data"))
> > > +		return -ENXIO;
> > > +
> > > +	/* LIS3 power on delay is quite long */
> > > +	msleep(lis3->pwron_delay / div);
> > > +	return 0;
> > > +}
> > 
> > The WARN_ONCE may not be very useful.  The user gets worried, might
> > report it (often to a distro, not to you!).  But we won't actually *do*
> > anything with the information?
> The sensor is used to park the hdd in case of an "accident". However,
> if the sensors is not working, the user should at least get a WARN
> that something is very wrong, right?

Well if we're doing this for the user's benefit (most WARNs are for developers)
then the message should be user-useful.  That one isn't, really.

Can we come up with some text which is more useful to the user/operator and
won't require him/her/it to send emails and raise bug reports?

Also, the stack trace which WARN emits is not useful in this application?