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From: David Brownell <david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
To: Trent Piepho <xyzzy-zY4eFNvK5D+xbKUeIHjxjQ@public.gmane.org>
Cc: i2c-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org
Subject: Re: [patch 2.6.26-rc1] i2c_use_client() defends against NULL
Date: Sat, 17 May 2008 11:53:04 -0700	[thread overview]
Message-ID: <200805171153.04995.david-b@pacbell.net> (raw)
In-Reply-To: <Pine.LNX.4.58.0805171048070.4196-13q4cmjDBaTP3RPoUHIrnuTW4wlIGRCZ@public.gmane.org>

On Saturday 17 May 2008, Trent Piepho wrote:
> > > Passing NULL to the current functions would just crash, it wouldn't
> > > morph anything.
> >
> > That's only if you assume an MMU set up to cause oopsing on reference
> > to the first and last pages of memory.  Not the best of assumptions...
> 
> Maybe BUG_ON(!client) would be better?  It seems more likely to catch
> a programming error.

BUG_ON() is almost always the wrong answer though ... it's only
appropriate when there's no way for the system to continue.

And in fact, here it's *not* a bug...

Passing NULL around is more often OK than not.  Example, it's
expected that passing it to a "free this object" routine will
work, saving callers a NULL check.  Similarly, refcount calls.


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      parent reply	other threads:[~2008-05-17 18:53 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-05-04 20:06 [patch 2.6.26-rc1] i2c_use_client() defends against NULL David Brownell
     [not found] ` <200805041306.21074.david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
2008-05-17 12:40   ` Jean Delvare
     [not found]     ` <20080517144007.7611ab32-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2008-05-17 13:57       ` David Brownell
     [not found]         ` <200805170657.56833.david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
2008-05-17 17:53           ` Trent Piepho
     [not found]             ` <Pine.LNX.4.58.0805171048070.4196-13q4cmjDBaTP3RPoUHIrnuTW4wlIGRCZ@public.gmane.org>
2008-05-17 18:53               ` David Brownell [this message]

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