linux-kernel - Re: [WARNING] local_bh_enable with irqs disabled:

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Message-Id: <200806112328.14814.david-b@pacbell.net>
Date:	Wed, 11 Jun 2008 23:28:14 -0700
From:	David Brownell <david-b@...bell.net>
To:	Guennadi Liakhovetski <g.liakhovetski@....de>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [WARNING] local_bh_enable with irqs disabled:

On Tuesday 10 June 2008, David Brownell wrote:
> On Thursday 05 June 2008, Guennadi Liakhovetski wrote:
> > Sorry, this was a 2.6.26-rc3 based kernel with the gpio-sysfs patch from 
> > David, e.g., http://marc.info/?l=linux-kernel&m=121107105300923&w=2,
> > which introduces a call to device_unregister via gpiochip_unexport(chip); 
> > in gpiochip_remove. 
> 
> Right.  Obviously that wasn't tested with "rmmod" of a modular
> GPIO expander ... I only have one board which supports such an
> expander right now, and it's not been in use recently.
> 
> A fix is obvious; any problems with what's below?

I verified it works for me on that one board ... after I removed
the board hooks that actually *use* those GPIOs (which prevent an
rmmod) and just use it from sysfs.  The missing test case has now
been covered.

I'll send an updated patch.

- Dave


> 
> - Dave
> 
> 
> --- g26.orig/drivers/gpio/gpiolib.c	2008-06-10 16:56:01.000000000 -0700
> +++ g26/drivers/gpio/gpiolib.c	2008-06-10 16:55:39.000000000 -0700
> @@ -726,12 +726,15 @@ int gpiochip_remove(struct gpio_chip *ch
>  		}
>  	}
>  	if (status == 0) {
> -		gpiochip_unexport(chip);
>  		for (id = chip->base; id < chip->base + chip->ngpio; id++)
>  			gpio_desc[id].chip = NULL;
>  	}
>  
>  	spin_unlock_irqrestore(&gpio_lock, flags);
> +
> +	if (status == 0)
> +		gpiochip_unexport(chip);
> +
>  	return status;
>  }
>  EXPORT_SYMBOL_GPL(gpiochip_remove);
> 
> 


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