Re: [PATCH -v2 14/33] locking,m68k: Implement atomic_fetch_{add,sub,and,or,xor}()

From: Andreas Schwab
Date: Mon Jun 20 2016 - 13:47:32 EST

Peter Zijlstra <peterz@xxxxxxxxxxxxx> writes:

> Could either of you comment on the below patch?
>
> All atomic functions that return a value should imply full memory
> barrier semantics -- this very much includes a compiler barrier / memory
> clobber.

I wonder if it is possible to find a case where this makes a real
difference, ie. where the compiler erroneously reused a value due to
the missing barrier.

Andreas.

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