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Date: Wed, 19 Feb 2020 15:54:24 -0400
From: Jason Gunthorpe <jgg@ziepe.ca>
Subject: Re: [PATCH 3/6] tracing: Wrap section comparison in
 tracer_alloc_buffers with COMPARE_SECTIONS
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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>

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