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From: Nick Desaulniers <ndesaulniers@google.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	clang-built-linux@googlegroups.com,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	"# 3.4.x" <stable@vger.kernel.org>,
	Nathan Chancellor <natechancellor@gmail.com>,
	Adhemerval Zanella <adhemerval.zanella@linaro.org>,
	Arnd Bergmann <arnd@arndb.de>,
	James Y Knight <jyknight@google.com>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Ingo Molnar <mingo@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Dan Williams <dan.j.williams@intel.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] lib/string.c: implement a basic bcmp
Date: Wed, 13 Mar 2019 11:51:09 -0700	[thread overview]
Message-ID: <CAKwvOdnheUi6Ho5u4akTLGa-tBeUq94hQJH0+a4ROe_aEUgo7g@mail.gmail.com> (raw)
In-Reply-To: <20190313144013.37cab5c7@gandalf.local.home>

On Wed, Mar 13, 2019 at 11:40 AM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Wed, 13 Mar 2019 11:17:15 -0700
> Nick Desaulniers <ndesaulniers@google.com> wrote:
>
> > +#ifndef __HAVE_ARCH_BCMP
> > +/**
> > + * bcmp - Like memcmp but a non-zero return code simply indicates a non-match.
> > + * @cs: One area of memory.
> > + * @ct: Another area of memory.
> > + * @count: The size of the areas.
> > + */
> > +#undef bcmp
> > +int bcmp(const void *cs, const void *ct, size_t count)
> > +{
> > +     return memcmp(cs, ct, count);
>
> This is confusing where the comment says "like memcmp but .." and then
> just returns memcmp() unmodified. If anything, I would expect to see
>
>         return !!memcmp(cs, ct, conut);

That's more work than strictly needed. memcmp already provides the
semantics of bcmp.  memcmp just provides more meaning to the
signedness of the return code, whereas bcmp does not.

>
> or have a better comment explaining why its the same.

I could add something about "the signedness of the return code not
providing any meaning."  What would you like to see in such a comment?
-- 
Thanks,
~Nick Desaulniers

  reply	other threads:[~2019-03-13 18:51 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-12 21:52 [PATCH] Makefile: Add '-fno-builtin-bcmp' to CLANG_FLAGS Nathan Chancellor
2019-03-12 22:55 ` Nick Desaulniers
2019-03-13  8:13 ` Rasmus Villemoes
2019-03-13 10:58   ` Masahiro Yamada
2019-03-13 13:44   ` Nathan Chancellor
2019-03-13 13:48     ` Arnd Bergmann
2019-03-13 15:32       ` Nathan Chancellor
2019-03-13 17:21         ` Nick Desaulniers
2019-03-13 17:27           ` Nick Desaulniers
2019-03-13 18:02             ` [PATCH] lib/string.c: implement a basic bcmp Nick Desaulniers
2019-03-13 18:11               ` Nick Desaulniers
2019-03-13 18:17                 ` [PATCH v2] " Nick Desaulniers
2019-03-13 18:40                   ` Steven Rostedt
2019-03-13 18:51                     ` Nick Desaulniers [this message]
2019-03-13 19:01                       ` Steven Rostedt
2019-03-13 19:34                         ` Rasmus Villemoes
2019-03-13 20:12                           ` Steven Rostedt
2019-03-13 20:37                             ` [PATCH v3] " Nick Desaulniers
2019-03-13 21:03                               ` Steven Rostedt
2019-03-13 21:13                                 ` [PATCH v4] " Nick Desaulniers
2019-03-14  3:15                                   ` Nathan Chancellor
2019-03-14  5:00                                   ` Masahiro Yamada
2019-03-14  8:33                                   ` Andy Shevchenko
2019-03-14  9:57                                   ` David Laight
2019-03-14  9:57                                     ` David Laight
2019-03-14 11:07                                     ` Rasmus Villemoes
2019-03-14 11:07                                       ` Rasmus Villemoes
2019-03-21  2:11                                   ` Andrew Morton
2019-03-21 17:02                                     ` Nick Desaulniers
2019-03-21 17:20                                       ` Nick Desaulniers
2019-03-21 21:05                                       ` Andrew Morton
2019-03-22  7:17                                       ` Rasmus Villemoes
2019-03-22  7:43                                         ` Sedat Dilek
2019-03-13 19:38             ` [PATCH] Makefile: Add '-fno-builtin-bcmp' to CLANG_FLAGS Arnd Bergmann
     [not found] ` <20190325003834.2F24E2133F@mail.kernel.org>
2019-03-25 14:02   ` Nathan Chancellor

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