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

From Andreas Schwab <schwab@linux-m68k.org>
Newsgroups linux.kernel
Subject Re: [PATCH -v2 14/33] locking,m68k: Implement atomic_fetch_{add,sub,and,or,xor}()
Date 2016-06-20 19:50 +0200
Message-ID <rMbuF-2Oc-3@gated-at.bofh.it> (permalink)
References (1 earlier) <rEPfz-1vx-1@gated-at.bofh.it> <rKCpj-72x-9@gated-at.bofh.it> <rKCyZ-75H-13@gated-at.bofh.it> <rKEUa-8qv-29@gated-at.bofh.it> <rL4bV-8nW-49@gated-at.bofh.it>
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Peter Zijlstra <peterz@infradead.org> 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.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
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Re: [PATCH -v2 14/33] locking,m68k: Implement atomic_fetch_{add,sub,and,or,xor}() Geert Uytterhoeven <geert@linux-m68k.org> - 2016-06-16 12:10 +0200
  Re: [PATCH -v2 14/33] locking,m68k: Implement  atomic_fetch_{add,sub,and,or,xor}() Peter Zijlstra <peterz@infradead.org> - 2016-06-16 12:20 +0200
    Re: [PATCH -v2 14/33] locking,m68k: Implement atomic_fetch_{add,sub,and,or,xor}() Andreas Schwab <schwab@linux-m68k.org> - 2016-06-16 14:50 +0200
      Re: [PATCH -v2 14/33] locking,m68k: Implement  atomic_fetch_{add,sub,and,or,xor}() Peter Zijlstra <peterz@infradead.org> - 2016-06-16 15:00 +0200
        Re: [PATCH -v2 14/33] locking,m68k: Implement atomic_fetch_{add,sub,and,or,xor}() Andreas Schwab <schwab@linux-m68k.org> - 2016-06-16 15:00 +0200
          Re: [PATCH -v2 14/33] locking,m68k: Implement atomic_fetch_{add,sub,and,or,xor}() Andreas Schwab <schwab@linux-m68k.org> - 2016-06-16 16:40 +0200
            Re: [PATCH -v2 14/33] locking,m68k: Implement  atomic_fetch_{add,sub,and,or,xor}() Peter Zijlstra <peterz@infradead.org> - 2016-06-16 17:00 +0200
              Re: [PATCH -v2 14/33] locking,m68k: Implement atomic_fetch_{add,sub,and,or,xor}() Andreas Schwab <schwab@linux-m68k.org> - 2016-06-16 17:10 +0200
                Re: [PATCH -v2 14/33] locking,m68k: Implement  atomic_fetch_{add,sub,and,or,xor}() Peter Zijlstra <peterz@infradead.org> - 2016-06-16 19:50 +0200
                Re: [PATCH -v2 14/33] locking,m68k: Implement atomic_fetch_{add,sub,and,or,xor}() Andreas Schwab <schwab@linux-m68k.org> - 2016-06-16 21:20 +0200
                Re: [PATCH -v2 14/33] locking,m68k: Implement atomic_fetch_{add,sub,and,or,xor}() Geert Uytterhoeven <geert@linux-m68k.org> - 2016-06-16 22:00 +0200
          Re: [PATCH -v2 14/33] locking,m68k: Implement  atomic_fetch_{add,sub,and,or,xor}() Peter Zijlstra <peterz@infradead.org> - 2016-06-16 16:40 +0200
      Re: [PATCH -v2 14/33] locking,m68k: Implement  atomic_fetch_{add,sub,and,or,xor}() Peter Zijlstra <peterz@infradead.org> - 2016-06-17 17:50 +0200
        Re: [PATCH -v2 14/33] locking,m68k: Implement atomic_fetch_{add,sub,and,or,xor}() Andreas Schwab <schwab@linux-m68k.org> - 2016-06-20 19:50 +0200
          Re: [PATCH -v2 14/33] locking,m68k: Implement  atomic_fetch_{add,sub,and,or,xor}() Finn Thain <fthain@telegraphics.com.au> - 2016-06-21 06:40 +0200

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