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

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* Ingo Molnar <mingo@kernel.org> wrote:

> But IMHO this really highlights a fundamental weakness of all this macro magic, 
> it's all way too fragile.
> 
> Why don't we introduce a boring family of APIs:
> 
> 	cmpxchg_8()
> 	cmpxchg_16()
> 	cmpxchg_32()
> 	cmpxchg_64()
> 
> 	xchg_or_32()
> 	xchg_or_64()
> 	...
> 
> ... with none of this pesky auto-typing property and none of the 
> macro-inside-a-macro crap? We could do clean types and would write them all in 
> proper C, not fragile CPP.
> 
> It's not like we migrate between the types all that frequently - and even if we 
> do, it's trivial.
> 
> hm?

So if we are still on the same page at this point, we'd have to add a pointer 
variant too I suspect:

	cmpxchg_ptr()
	xchg_ptr()

... whose bitness may differ between architectures(subarches), but it would still 
be a single variant per architecture, i.e. still with pretty clear type 
propagation and with a very clear notion of which architecture supports what.

It looks like a lot of work, but it's all low complexity work AFAICS that could be 
partly automated.

Thanks,

	Ingo

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Thread

[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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