Re: Linux 3.19-rc3

Kent Overstreet
2015-01-06T12:42:57Z

On Tue, Jan 06, 2015 at 01:20:06PM +0100, Peter Zijlstra wrote:
> We (probably me) should probably audit all the atomic_xchg()
> implementations and documentation and fix that. I was very much under
> the impression it should imply a full barrier (and it certainly does on
> x86), the documentation should state the rule that any atomic_ function
> that returns a result is fully serializing, therefore, because
> atomic_xchg() has a return value, it should too.

I think that the documentation was changed awhile ago - I'd have to check and I
should sleep, though. It was probably 4-5 years ago that I saw that old weird
"atomic_xchg() doesn't imply barriers" thing.