Messages in this thread | | | Date | Mon, 20 Aug 2007 09:31:29 -0400 | From | Chris Snook <> | Subject | Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures |
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Christoph Lameter wrote: > On Fri, 17 Aug 2007, Paul E. McKenney wrote: > >> On Sat, Aug 18, 2007 at 08:09:13AM +0800, Herbert Xu wrote: >>> On Fri, Aug 17, 2007 at 04:59:12PM -0700, Paul E. McKenney wrote: >>>> gcc bugzilla bug #33102, for whatever that ends up being worth. ;-) >>> I had totally forgotten that I'd already filed that bug more >>> than six years ago until they just closed yours as a duplicate >>> of mine :) >>> >>> Good luck in getting it fixed! >> Well, just got done re-opening it for the third time. And a local >> gcc community member advised me not to give up too easily. But I >> must admit that I am impressed with the speed that it was identified >> as duplicate. >> >> Should be entertaining! ;-) > > Right. ROTFL... volatile actually breaks atomic_t instead of making it > safe. x++ becomes a register load, increment and a register store. Without > volatile we can increment the memory directly. It seems that volatile > requires that the variable is loaded into a register first and then > operated upon. Understandable when you think about volatile being used to > access memory mapped I/O registers where a RMW operation could be > problematic.
So, if we want consistent behavior, we're pretty much screwed unless we use inline assembler everywhere?
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