Re: [PATCH v8 09/14] lockdep: Apply crossrelease to completions

From	Arnd Bergmann <arnd@arndb.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH v8 09/14] lockdep: Apply crossrelease to completions
Date	2017-08-19 15:40 +0200
Message-ID	<ugc8O-1SQ-5@gated-at.bofh.it> (permalink)
References	<ubKut-59V-3@gated-at.bofh.it> <ubKuv-59V-37@gated-at.bofh.it> <uejo5-1Xt-11@gated-at.bofh.it> <ufZbz-25E-1@gated-at.bofh.it> <ugbw6-1pj-9@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Sat, Aug 19, 2017 at 2:51 PM, Arnd Bergmann <arnd@arndb.de> wrote:

>> --- a/include/linux/completion.h
>> +++ b/include/linux/completion.h
>> @@ -74,7 +74,7 @@ static inline void complete_release_commit(struct completion *x) {}
>>  #endif
>>
>>  #define COMPLETION_INITIALIZER_ONSTACK(work) \
>> -       ({ init_completion(&work); work; })
>> +       (*({ init_completion(&work); &work; }))
>>
>>  /**
>>   * DECLARE_COMPLETION - declare and initialize a completion structure
>
> Nice hack. Any idea why that's different to the compiler?
>
> I've applied that one to my test tree now, and reverted my own patch,
> will let you know if anything else shows up. I think we probably want
> to merge both patches to mainline.

There is apparently one user of COMPLETION_INITIALIZER_ONSTACK
that causes a regression with the patch above:

drivers/acpi/nfit/core.c: In function 'acpi_nfit_flush_probe':
include/linux/completion.h:77:3: error: value computed is not used
[-Werror=unused-value]
  (*({ init_completion(&work); &work; }))

It would be trivial to convert to init_completion(), which seems to be
what was intended there.

        Arnd

Thread

Re: [PATCH v8 09/14] lockdep: Apply crossrelease to completions Arnd Bergmann <arnd@arndb.de> - 2017-08-14 11:00 +0200
  Re: [PATCH v8 09/14] lockdep: Apply crossrelease to completions Boqun Feng <boqun.feng@gmail.com> - 2017-08-19 01:50 +0200
    Re: [PATCH v8 09/14] lockdep: Apply crossrelease to completions Arnd Bergmann <arnd@arndb.de> - 2017-08-19 15:00 +0200
      Re: [PATCH v8 09/14] lockdep: Apply crossrelease to completions Arnd Bergmann <arnd@arndb.de> - 2017-08-19 15:40 +0200
        Re: [PATCH v8 09/14] lockdep: Apply crossrelease to completions Boqun Feng <boqun.feng@gmail.com> - 2017-08-23 16:50 +0200
      Re: [PATCH v8 09/14] lockdep: Apply crossrelease to completions Boqun Feng <boqun.feng@gmail.com> - 2017-08-20 05:20 +0200

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