From: Steven Rostedt <rostedt@goodmis.org>
To: Nathan Chancellor <natechancellor@gmail.com>
Cc: 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>,
linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
linux-arch@vger.kernel.org, linux-mm@kvack.org,
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 09:34:45 -0500 [thread overview]
Message-ID: <20200219093445.386f1c09@gandalf.local.home> (raw)
In-Reply-To: <20200219045423.54190-4-natechancellor@gmail.com>
On Tue, 18 Feb 2020 21:54:20 -0700
Nathan Chancellor <natechancellor@gmail.com> wrote:
> Clang warns:
>
> ../kernel/trace/trace.c:9335:33: warning: array comparison always
> evaluates to true [-Wtautological-compare]
> if (__stop___trace_bprintk_fmt != __start___trace_bprintk_fmt)
> ^
> 1 warning generated.
>
> These are not true arrays, they are linker defined symbols, which are
> just addresses so there is not a real issue here. Use the
> COMPARE_SECTIONS macro to silence this warning by casting the linker
> defined symbols to unsigned long, which keeps the logic the same.
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/765
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
> kernel/trace/trace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index c797a15a1fc7..e1f3b16e457b 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -9332,7 +9332,7 @@ __init static int tracer_alloc_buffers(void)
> goto out_free_buffer_mask;
>
> /* Only allocate trace_printk buffers if a trace_printk exists */
> - if (__stop___trace_bprintk_fmt != __start___trace_bprintk_fmt)
> + if (COMPARE_SECTIONS(__stop___trace_bprintk_fmt, !=, __start___trace_bprintk_fmt))
Sorry, but this is really ugly and unreadable. Please find some other
solution to fix this.
NAK-by: Steven Rostedt
-- Steve
> /* Must be called before global_trace.buffer is allocated */
> trace_printk_init_buffers();
>
next prev parent reply other threads:[~2020-02-19 14:34 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 [this message]
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
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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