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Re: [PATCH] atomic: Fix bugs in 'fetch_or()' and rename it to 'xchg_or()'

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On Tue, Mar 15, 2016 at 10:32:45AM +0100, Ingo Molnar wrote:
>  2) its naming sucks. "fetch_or()" does not really signal that it's a
>     fundamentally atomic operation, nor what API family it belongs to.

I disagree there, the fetch-$op naming is widely used for atomic
operations that return the previous value. See for example the C/C++11
atomic ops.

I've even thought about reworking our entire atomic*_t bits to match.
That is, introduce all the fetch_$op primitives, then convert all the
$op_return ones over and finally remove all the $op_return ones.

I've not done so because we're all so very used to $op_return that I'm
sure people (and this would very much include me) would curse me for
changing this.

The reason for fetch_$op is that it also works for irreversible
operations like or. With or_return you simply cannot tell what the
previous state was (with add_return you can do a simple subtraction to
revert to the prior state).

And yes, some people use the xchg-$op naming, but its less widely used
(x86 asm being one). Other also use swap-$op.

In any case, I prefer the name as it was.

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[GIT PULL] NOHZ updates for v4.6 Ingo Molnar <mingo@kernel.org> - 2016-03-14 13:40 +0100
  Re: [GIT PULL] NOHZ updates for v4.6 Linus Torvalds <torvalds@linux-foundation.org> - 2016-03-15 03:50 +0100
    Re: [GIT PULL] NOHZ updates for v4.6 Peter Zijlstra <peterz@infradead.org> - 2016-03-15 09:50 +0100
      Re: [GIT PULL] NOHZ updates for v4.6 Ingo Molnar <mingo@kernel.org> - 2016-03-15 10:50 +0100
    [PATCH] atomic: Fix bugs in 'fetch_or()' and rename it to 'xchg_or()' Ingo Molnar <mingo@kernel.org> - 2016-03-15 10:40 +0100
      Re: [PATCH] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Peter Zijlstra <peterz@infradead.org> - 2016-03-15 12:00 +0100
        Re: [PATCH] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Ingo Molnar <mingo@kernel.org> - 2016-03-15 13:10 +0100
          Re: [PATCH] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Peter Zijlstra <peterz@infradead.org> - 2016-03-15 13:50 +0100
      Re: [PATCH] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Peter Zijlstra <peterz@infradead.org> - 2016-03-15 12:10 +0100
      Re: [PATCH] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Ingo Molnar <mingo@kernel.org> - 2016-03-15 13:10 +0100
        Re: [PATCH] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Ingo Molnar <mingo@kernel.org> - 2016-03-15 13:40 +0100
          Re: [PATCH] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Ingo Molnar <mingo@kernel.org> - 2016-03-15 13:40 +0100
          Re: [PATCH] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Peter Zijlstra <peterz@infradead.org> - 2016-03-15 14:20 +0100
      Re: [PATCH] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Peter Zijlstra <peterz@infradead.org> - 2016-03-15 13:30 +0100
      [PATCH v2] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Ingo Molnar <mingo@kernel.org> - 2016-03-15 13:30 +0100
        Re: [PATCH v2] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Peter Zijlstra <peterz@infradead.org> - 2016-03-15 14:30 +0100
          Re: [PATCH v2] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Ingo Molnar <mingo@kernel.org> - 2016-03-16 09:10 +0100
            Re: [PATCH v2] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Peter Zijlstra <peterz@infradead.org> - 2016-03-16 09:40 +0100
        Re: [PATCH v2] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Frederic Weisbecker <fweisbec@gmail.com> - 2016-03-15 18:10 +0100
          Re: [PATCH v2] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Ingo Molnar <mingo@kernel.org> - 2016-03-16 09:20 +0100
            Re: [PATCH v2] atomic: Fix bugs in 'fetch_or()' and rename it to  'xchg_or()' Frederic Weisbecker <fweisbec@gmail.com> - 2016-03-17 02:00 +0100
      Re: [PATCH] atomic: Fix bugs in 'fetch_or()' and rename it to 'xchg_or()' Linus Torvalds <torvalds@linux-foundation.org> - 2016-03-15 17:20 +0100
    [PATCH] nohz: Change tick_dep_mask from 'unsigned long' to 'unsigned  int' Ingo Molnar <mingo@kernel.org> - 2016-03-15 11:00 +0100
      Re: [PATCH] nohz: Change tick_dep_mask from 'unsigned long' to  'unsigned int' Ingo Molnar <mingo@kernel.org> - 2016-03-15 13:20 +0100
        Re: [PATCH] nohz: Change tick_dep_mask from 'unsigned long' to  'unsigned int' Linus Torvalds <torvalds@linux-foundation.org> - 2016-03-15 17:40 +0100
          Re: [PATCH] nohz: Change tick_dep_mask from 'unsigned long' to  'unsigned int' Frederic Weisbecker <fweisbec@gmail.com> - 2016-03-15 18:30 +0100
            Re: [PATCH] nohz: Change tick_dep_mask from 'unsigned long' to  'unsigned int' Linus Torvalds <torvalds@linux-foundation.org> - 2016-03-15 18:40 +0100

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