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From: Jason Gunthorpe <jgg@ziepe.ca>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nathan Chancellor <natechancellor@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Michal Marek <michal.lkml@markovi.net>,
	Arnd Bergmann <arnd@arndb.de>, Ingo Molnar <mingo@redhat.com>,
	Jason Baron <jbaron@akamai.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	Linux Memory Management List <linux-mm@kvack.org>,
	clang-built-linux <clang-built-linux@googlegroups.com>
Subject: Re: [PATCH 3/6] tracing: Wrap section comparison in tracer_alloc_buffers with COMPARE_SECTIONS
Date: Wed, 19 Feb 2020 15:54:24 -0400	[thread overview]
Message-ID: <20200219195424.GW31668@ziepe.ca> (raw)
In-Reply-To: <CAKwvOd=8vb5eOjiLg96zr25Xsq_Xge_Ym7RsNqKK8g+ZR9KWzA@mail.gmail.com>

On Wed, Feb 19, 2020 at 11:11:19AM -0800, Nick Desaulniers wrote:
> > Godbolt says clang is happy if it is written as:
> >
> >   if (&__stop___trace_bprintk_fmt[0] != &__start___trace_bprintk_fmt[0])
> >
> > Which is probably the best compromise. The type here is const char
> > *[], so it would be a shame to see it go.
> 
> If the "address" is never dereferenced, but only used for arithmetic
> (in a way that the the pointed to type is irrelevant), does the
> pointed to type matter? 

The type is used here:

        if (*pos < start_index)
                return __start___trace_bprintk_fmt + *pos;

The return expression should be a const char **

Presumably the caller of find_next derferences it.

Jason


  parent reply	other threads:[~2020-02-19 19:54 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-19  4:54 [PATCH 0/6] Silence some instances of -Wtautological-compare and enable globally Nathan Chancellor
2020-02-19  4:54 ` [PATCH 1/6] asm/sections: Add COMPARE_SECTIONS macro Nathan Chancellor
2020-02-19  4:54 ` [PATCH 2/6] kernel/extable: Wrap section comparison in sort_main_extable with COMPARE_SECTIONS Nathan Chancellor
2020-02-19  4:54 ` [PATCH 3/6] tracing: Wrap section comparison in tracer_alloc_buffers " Nathan Chancellor
2020-02-19 14:34   ` Steven Rostedt
2020-02-19 17:44     ` Nick Desaulniers
2020-02-19 18:16       ` Jason Gunthorpe
2020-02-19 19:09         ` Steven Rostedt
2020-02-19 19:11         ` Nick Desaulniers
2020-02-19 19:22           ` Nathan Chancellor
2020-02-19 19:43             ` Steven Rostedt
2020-02-19 19:54           ` Jason Gunthorpe [this message]
2020-02-19 21:32             ` Nick Desaulniers
2020-02-19  4:54 ` [PATCH 4/6] dynamic_debug: Wrap section comparison in dynamic_debug_init " Nathan Chancellor
2020-02-19  4:54 ` [PATCH 5/6] mm: kmemleak: Wrap section comparison in kmemleak_init " Nathan Chancellor
2020-02-19  4:54 ` [PATCH 6/6] kbuild: Enable -Wtautological-compare Nathan Chancellor
2020-04-21  4:03 ` [PATCH 0/6] Silence some instances of -Wtautological-compare and enable globally Andrew Morton
2020-04-21  4:32   ` Nathan Chancellor

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