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Date: Thu, 2 Feb 2012 11:54:56 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Peter Meerwald <pmeerw@pmeerw.net>
Cc: linux-kernel@vger.kernel.org, lars@metafoo.de, rpurdie@rpsys.net
Subject: Re: [PATCH v2] add LED driver for PCA9663 I2C chip
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On Thu, 2 Feb 2012 11:42:09 +0100 (CET)
Peter Meerwald <pmeerw@pmeerw.net> wrote:

> 
> > Andrew Morton <akpm@linux-foundation.org> wrote:
> > > > +exit:
> > > > +	while (i--) {
> > > > +		led_classdev_unregister(&pca9633[i].led_cdev);
> > > > +		cancel_work_sync(&pca9633[i].work);
> > > > +	}
> > > This (untested!) loop has an off-by-one error. 
> 
> > Well, it's partly wrong.  It's wrong for the cancel_work_sync() but not
> > for the led_classdev_unregister().  The cancel_work_sync() can just be
> > removed: we haven't scheduled any works yet.
> 
> there are 4 leds with get led_classdev_register()ed
> 
> wouldn't it be possible that someone is starting to use led1 while led3 has 
> not been registered yet? if registration for led3 fails, the exit code 
> (above) is called and there might be work scheduled
> 
> so (hypothetically):
> register led1 -> ok
> register led2 -> ok
> use led1 (schedule work)
> register led3 -> fail -> exit code
> 
> the code has been copied from other led drivers
> I think there is no harm to keep cancel_work_sync()

Spose so - it won't hurt.  And I was wrong about there being an
off-by-one.