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Date: Wed, 20 May 2026 15:42:19 -0700
From: Nathan Chancellor <nathan@kernel.org>
To: Thomas =?iso-8859-1?Q?Wei=DFschuh?= <linux@weissschuh.net>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Vincent Donnefort <vdonnefort@google.com>,
	Marc Zyngier <maz@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH] tracing: Create output file from cmd_check_undefined
Message-ID: <20260520224219.GC1607511@ax162>
References: <20260520-tracing-ringbuffer-check-v1-1-d979cfab1338@weissschuh.net>
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In-Reply-To: <20260520-tracing-ringbuffer-check-v1-1-d979cfab1338@weissschuh.net>

On Wed, May 20, 2026 at 08:01:55PM +0200, Thomas Weißschuh wrote:
> As the output file is currently never created, the check will run every
> time, even if the inputs have not changed.
> 
> Create an empty output file which allows make to skip the execution when
> it is not necessary.
> 
> Fixes: 1211907ac0b5 ("tracing: Generate undef symbols allowlist for simple_ring_buffer")
> Fixes: 58b4bd18390e ("tracing: Adjust cmd_check_undefined to show unexpected undefined symbols")
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  kernel/trace/Makefile | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
> index 1decdce8cbef..b5797457f9f4 100644
> --- a/kernel/trace/Makefile
> +++ b/kernel/trace/Makefile
> @@ -154,7 +154,8 @@ quiet_cmd_check_undefined = NM      $<
>                echo "Unexpected symbols in $<:" >&2; \
>                echo "$$undefsyms" >&2; \
>                false; \
> -          fi
> +          fi; \
> +          touch $@
>  
>  $(obj)/%.o.checked: $(obj)/%.o $(obj)/undefsyms_base.o FORCE
>  	$(call if_changed,check_undefined)
> 
> ---
> base-commit: 254f49634ee16a731174d2ae34bc50bd5f45e731
> change-id: 20260520-tracing-ringbuffer-check-3a6e748d37b7
> 
> Best regards,
> --  
> Thomas Weißschuh <linux@weissschuh.net>
> 

-- 
Cheers,
Nathan