Re: [PATCH] Fix WARN_ON / WARN_ON_ONCE regression

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On Tue, 2006-10-10 at 09:04 -0400, Steven Rostedt wrote:

> 
> Holy crap!  I wonder where else in the kernel gcc is doing this. (of
> course I'm using gcc4 so I don't know).  Is there another gcc attribute
> to actually tell gcc that a variable is really mostly read only (besides
> placing it in a mostly read only elf section)?
> 
> What was wrong with the original WARN_ON_ONCE with
> 
>   if (unlikely(condition) && __warn_once)
> 
> This didn't have the cache crash problem too, did it?
> I don't have a gcc3 around to test.

In the original WARN_ON_ONCE, gcc3 only writes to __warn_once when
(condition) is true.  So it does not cause cache bouncing by always
writing to __warn_once.

Tim
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