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From: Dan Williams <dan.j.williams@intel.com>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Linux MM <linux-mm@kvack.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Michel Lespinasse <walken@google.com>,
	Byungchul Park <byungchul.park@lge.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Matthew Wilcox <willy@infradead.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	kernel-team@lge.com, "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Len Brown <lenb@kernel.org>,
	"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
	Linux ACPI <linux-acpi@vger.kernel.org>
Subject: Re: [PATCH v2 1/2] nfit: Fix the abuse of COMPLETION_INITIALIZER_ONSTACK()
Date: Thu, 24 Aug 2017 17:36:22 -0700	[thread overview]
Message-ID: <CAPcyv4gHgdpyqbv8gs5MiEtEHSdC-JLhutdfn81fhQ1woQSh_Q@mail.gmail.com> (raw)
In-Reply-To: <20170824142239.15178-1-boqun.feng@gmail.com>

On Thu, Aug 24, 2017 at 7:22 AM, Boqun Feng <boqun.feng@gmail.com> wrote:
> COMPLETION_INITIALIZER_ONSTACK() is supposed to used as an initializer,
> in other words, it should only be used in assignment expressions or
> compound literals. So the usage in drivers/acpi/nfit/core.c:
>
>         COMPLETION_INITIALIZER_ONSTACK(flush.cmp);
>
> , is inappropriate.
>
> Besides, this usage could also break compilations for another fix to
> reduce stack sizes caused by COMPLETION_INITIALIZER_ONSTACK(), because
> that fix changes COMPLETION_INITIALIZER_ONSTACK() from rvalue to lvalue,
> and usage as above will report error:
>
>         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; }))
>
> This patch fixes this by replacing COMPLETION_INITIALIZER_ONSTACK() with
> init_completion() in acpi_nfit_flush_probe(), which does the same
> initialization without any other problem.
>
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>

Acked-by: Dan Williams <dan.j.williams@intel.com>

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  parent reply	other threads:[~2017-08-25  0:36 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-23 15:25 [PATCH 0/2] completion: Reduce stack usage caused by COMPLETION_INITIALIZER_ONSTACK() Boqun Feng
2017-08-23 15:25 ` [PATCH 1/2] nfit: Use init_completion() in acpi_nfit_flush_probe() Boqun Feng
2017-08-23 22:08   ` Dan Williams
2017-08-24 13:07   ` Thomas Gleixner
2017-08-24 13:28     ` Boqun Feng
2017-08-24 13:46       ` Arnd Bergmann
2017-08-24 14:22   ` [PATCH v2 1/2] nfit: Fix the abuse of COMPLETION_INITIALIZER_ONSTACK() Boqun Feng
2017-08-25  0:18     ` Boqun Feng
2017-08-25  0:36     ` Dan Williams [this message]
2017-08-23 15:25 ` [PATCH 2/2] completion: Avoid unnecessary stack allocation for COMPLETION_INITIALIZER_ONSTACK() Boqun Feng
2017-08-23 15:33 ` [PATCH 0/2] completion: Reduce stack usage caused by COMPLETION_INITIALIZER_ONSTACK() Arnd Bergmann

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