Herbert Xu wrote:

On Thu, Aug 16, 2007 at 03:48:54PM -0400, Chris Snook wrote:

quoted

quoted

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