Messages in this thread | | | Date | Fri, 10 Aug 2007 21:29:43 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH 6/24] make atomic_read() behave consistently on frv |
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On Sat, Aug 11, 2007 at 08:54:46AM +0800, Herbert Xu wrote: > Chris Snook <csnook@redhat.com> wrote: > > > > cpu_relax() contains a barrier, so it should do the right thing. For > > non-smp architectures, I'm concerned about interacting with interrupt > > handlers. Some drivers do use atomic_* operations. > > What problems with interrupt handlers? Access to int/long must > be atomic or we're in big trouble anyway.
Reordering due to compiler optimizations. CPU reordering does not affect interactions with interrupt handlers on a given CPU, but reordering due to compiler code-movement optimization does. Since volatile can in some cases suppress code-movement optimizations, it can affect interactions with interrupt handlers.
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