Subject: Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures

From: Chris Snook <[email-masked]>
Date: Thu, 16 Aug 2007 22:04:24 -0400

Herbert Xu wrote:
> On Thu, Aug 16, 2007 at 03:48:54PM -0400, Chris Snook wrote:
>>> Can you find an actual atomic_read code snippet there that is
>>> broken without the volatile modifier?
>> A whole bunch of atomic_read uses will be broken without the volatile 
>> modifier once we start removing barriers that aren't needed if volatile 
>> behavior is guaranteed.
> 
> Could you please cite the file/function names so we can
> see whether removing the barrier makes sense?
> 
> Thanks,

At a glance, several architectures' implementations of smp_call_function() have 
one or more legitimate atomic_read() busy-waits that shouldn't be using 
CPU-relax.  Some of them do work in the loop.

I'm sure there are plenty more examples that various maintainers could find in 
their own code.

	-- Chris