Re: wrong driver remove order

[Guennadi Liakhovetski <g.liakhovetski-Mmb7MZpHnFY@public.gmane.org>]

On Tue, 25 Nov 2008, Jean Delvare wrote:

> On Mon, 17 Nov 2008 22:04:17 +0100, Jean Delvare wrote:
> > Hi Guennadi,
> > 
> > On Thu, 30 Oct 2008 15:13:14 +0100 (CET), Guennadi Liakhovetski wrote:
> > > Hi,
> > > 
> > > I have two i2c modules, one of which uses the other one: a camera and a 
> > > GPIO-extender, and the camera uses a GPIO from that extender. I first load 
> > > the GPIO-extender driver (pca953x.c), then the camera (mt9m001.c), then as 
> > > I tried to remove the bus driver (i2c-mxc, not yet in the mainline), first 
> > > the GPIO-extender's .remove() method has been called, which, of course, 
> > > failed, because mt9m001 was still holding its GPIO... AFAIU, the remove 
> > > order should be reverse from probe, right?
> > 
> > It would indeed make sense for the removal order to be the reverse of
> > the bind order. Can you please try the following patch and report if it
> > solves your problem?
> 
> Any news from this? I'd like to push this change to Linus this week if
> it actually solves your problem.

Sorry, I didn't forget, I just was postponing this test, until I get more 
time... I've tested it now - it does solve the problem, thanks!

Tested-by: Guennadi Liakhovetski <g.liakhovetski-Mmb7MZpHnFY@public.gmane.org>

Thanks
Guennadi

> 
> > From: Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
> > Subject: i2c: Remove i2c clients in reverse order
> > 
> > i2c clients should be removed in reverse order compared to the probe
> > (actually: bind) order. This matters when several clients depend on
> > each other.
> > 
> > Signed-off-by: Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
> > Cc: Guennadi Liakhovetski <g.liakhovetski-Mmb7MZpHnFY@public.gmane.org>
> > ---
> >  drivers/i2c/i2c-core.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > --- linux-2.6.28-rc5.orig/drivers/i2c/i2c-core.c	2008-11-17 21:29:59.000000000 +0100
> > +++ linux-2.6.28-rc5/drivers/i2c/i2c-core.c	2008-11-17 21:44:06.000000000 +0100
> > @@ -631,7 +631,7 @@ int i2c_del_adapter(struct i2c_adapter *
> >  
> >  	/* detach any active clients. This must be done first, because
> >  	 * it can fail; in which case we give up. */
> > -	list_for_each_entry_safe(client, _n, &adap->clients, list) {
> > +	list_for_each_entry_safe_reverse(client, _n, &adap->clients, list) {
> >  		struct i2c_driver	*driver;
> >  
> >  		driver = client->driver;
> 
> -- 
> Jean Delvare
> 

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer