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From: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
To: David Brownell <david-b@pacbell.net>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] prevent gpio chip drivers from unloading while used
Date: Sat, 9 Feb 2008 12:41:45 +0100 (CET)	[thread overview]
Message-ID: <Pine.LNX.4.64.0802091240160.4147@axis700.grange> (raw)
In-Reply-To: <200802081714.18795.david-b@pacbell.net>

On Fri, 8 Feb 2008, David Brownell wrote:

> > Yes, that's what I'm saying. I had a GPIO in use and rmmod-ed pca953x. It 
> > did produce an error message
> > 
> > pca953x 0-0041: gpiochip_remove() failed, -16
> > 
> > , but rmmod completed.
> 
> Doesn't that seem buglike to you?
> 
> Oh, right -- the module exit code will ignore that status, it doesn't
> even have a way to report failures any more.  Crap.
> 
> So it looks like we have no choice but to do this.  Can you make sure
> all the rmmod-capable gpio_chip drivers support this?  Ignore the SOC
> support, that never supports rmmod -- just the stuff in drivers/gpio.

As long as you find these two patches acceptable, I'll cook up an 
incremental patch to fix those.

> > AFAIU, the only 2 ways currently to prevent rmmod  
> > from completing, are: increment module use-count, then the respective 
> > module_exit() function is not called at all and rmmod fails with -EBUSY. 
> > Or block in rmmod until the resource becomes free. None of these has 
> > happened. BTW, I think, there's the same problem with i2c adapter drivers.
> 
> Right.  In fact, every time you'd expect driver removal errors to
> cause module removal to fail.   Maybe this is part of that whole
> "should we even *support* rmmod" discussion, which I tuned out.

We don't want to start another one here, do we?:-)

Thanks
Guennadi
---
Guennadi Liakhovetski

      reply	other threads:[~2008-02-09 11:41 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-08 11:10 Guennadi Liakhovetski
2008-02-09  0:01 ` David Brownell
2008-02-09  0:45   ` Guennadi Liakhovetski
2008-02-09  1:14     ` David Brownell
2008-02-09 11:41       ` Guennadi Liakhovetski [this message]

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