linux-kernel - Re: [RFC, PATCH 1/3] gpiodev

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Message-ID: <20070411074214.GB3752@flint.arm.linux.org.uk>
Date:	Wed, 11 Apr 2007 08:42:14 +0100
From:	Russell King <rmk+lkml@....linux.org.uk>
To:	Juergen Schindele <schindele@...tec.de>
Cc:	Paul Sokolovsky <pmiscml@...il.com>,
	linux-arm-kernel@...ts.arm.linux.org.uk,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC, PATCH 1/3] gpiodev - API definitions

On Wed, Apr 11, 2007 at 08:47:01AM +0200, Juergen Schindele wrote:
> Am Dienstag, 10. April 2007 23:30 schrieb Paul Sokolovsky:
> > +static inline int gpiodev_get_value(struct gpio *gpio)
> > +{
> > +       struct gpiodev_ops *ops = gpio->gpio_dev->dev.platform_data;
> 
> wouldn't it be more sure to verify if xxx function is NOT null
> before using it ?? Perhaps something like that
> 	     BUG_ON(!ops->get);
> 
> > +       return ops->get(&gpio->gpio_dev->dev, gpio->gpio_no);

What does the BUG_ON buy us that oopsing due to a NULL pointer deref
doesn't?  Both cases you end up with a register dump and backtrace.
In fact, on ARM the NULL pointer deref provides a more accurate
register dump and backtrace than BUG_ON() can ever do.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:
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