Re: [GIT PULL] percpu fix for v4.10-rc6

From	Tejun Heo <tj@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [GIT PULL] percpu fix for v4.10-rc6
Date	2017-01-31 23:30 +0100
Message-ID	<t5P62-6fV-27@gated-at.bofh.it> (permalink)
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On Tue, Jan 31, 2017 at 02:17:10PM -0800, Linus Torvalds wrote:
> Because there definitely have been users of the bitop routines that
> assign the result to an "int", and I have some dim memory of us also
> having had things like drivers that made their own "bool" variables
> and use "char" for them.
> 
> But I'm not seeing it. The generic bitop pattern seems to be
> 
>     static inline int test_and_change_bit(int nr, volatile unsigned long *addr)
>     ...
>         return (old & mask) != 0;
> 
> which is fine.
> 
> Just exactly what code did you look at?

My bad.  I misread the generic test_bit() code and was reading the
inner helper of ppc, DEFINE_TESTOP macro, which returns the masked
value.  We used to have this problem, right?  I seem to have a memory
of hitting this issue.

Is there a reason we don't make these functions explicitly return
bool?  To avoid unnecessary boolean conversion by the compiler?  If
so, there gotta be a way to avoid that.

Thanks.

-- 
tejun

Thread

[GIT PULL] percpu fix for v4.10-rc6 Tejun Heo <tj@kernel.org> - 2017-01-31 18:00 +0100
  Re: [GIT PULL] percpu fix for v4.10-rc6 Linus Torvalds <torvalds@linux-foundation.org> - 2017-01-31 22:50 +0100
    Re: [GIT PULL] percpu fix for v4.10-rc6 Linus Torvalds <torvalds@linux-foundation.org> - 2017-01-31 22:50 +0100
      Re: [GIT PULL] percpu fix for v4.10-rc6 Tejun Heo <tj@kernel.org> - 2017-01-31 23:20 +0100
        Re: [GIT PULL] percpu fix for v4.10-rc6 Tejun Heo <tj@kernel.org> - 2017-01-31 23:30 +0100
          Re: [GIT PULL] percpu fix for v4.10-rc6 Linus Torvalds <torvalds@linux-foundation.org> - 2017-02-01 01:40 +0100
        Re: [GIT PULL] percpu fix for v4.10-rc6 Linus Torvalds <torvalds@linux-foundation.org> - 2017-01-31 23:30 +0100
    Re: [GIT PULL] percpu fix for v4.10-rc6 David Howells <dhowells@redhat.com> - 2017-02-01 09:00 +0100
      Re: [GIT PULL] percpu fix for v4.10-rc6 David Howells <dhowells@redhat.com> - 2017-02-01 11:10 +0100

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