linux-kernel - Re: [GPIO]implement sleeping GPIO chip removal

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Date:	Wed, 10 Nov 2010 14:15:40 -0700
From:	Grant Likely <grant.likely@...retlab.ca>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Maciej Szmigiero <mhej@...pl>, linux-kernel@...r.kernel.org,
	linux-arch@...r.kernel.org,
	Anton Vorontsov <avorontsov@...mvista.com>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Uwe Kleine-K?nig <u.kleine-koenig@...gutronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arnd Bergmann <arnd@...db.de>,
	Jonathan Cameron <jic23@....ac.uk>,
	Ben Nizette <bn@...sdigital.com>
Subject: Re: [GPIO]implement sleeping GPIO chip removal

On Wed, Nov 10, 2010 at 10:07:05PM +0100, Thomas Gleixner wrote:
> Can you please use a mail client which does proper line breaks at 78 ?
> 
> On Wed, 10 Nov 2010, Maciej Szmigiero wrote:
> > You misunderstood me.
> 
> No, I didnt.
> 
> > By "looping in hope that somebody will finally release the chip" I
> > meant the only real way to handle a GPIO chip unplugging in the
> > current kernel.  Which is way worse that preventing new requests,
> > then waiting for existing one to be released.  And this is exactly
> > what my patch does.
> 
> That still does not make it a good solution.
> 
> > I understand that it could be simplified by removing redundant code
> > (as Grant Likely had suggested before), and moving it to completion
> > interface instead of manipulating a task structure directly, but
> > this doesn't mean that the whole GPIO code has to be rewritten just
> > to add one functionality.
> 
> It's not about rewriting, it's about fixing the problem in the right
> way and not just hacking around it.
> 
> If we see a shortcoming like this, we fix it and do not magically work
> around it.

+1

Thomas is right.  kobject reference counting is the correct solution.
Nack on this approach.

g.

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