linux-kernel - Re: [PATCH] perf/x86/intel: Use guard() instead of mutex

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Message-ID: <eab90856-7066-4de9-9080-f2479225ad00@web.de>
Date: Tue, 2 Sep 2025 18:54:52 +0200
From: Markus Elfring <Markus.Elfring@....de>
To: Liao Yuanhong <liaoyuanhong@...o.com>, linux-perf-users@...r.kernel.org,
 x86@...nel.org
Cc: LKML <linux-kernel@...r.kernel.org>,
 Adrian Hunter <adrian.hunter@...el.com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Arnaldo Carvalho de Melo <acme@...nel.org>, Borislav Petkov <bp@...en8.de>,
 Dave Hansen <dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>,
 Ian Rogers <irogers@...gle.com>, Ingo Molnar <mingo@...hat.com>,
 Jiri Olsa <jolsa@...nel.org>, Kan Liang <kan.liang@...ux.intel.com>,
 Mark Rutland <mark.rutland@....com>, Namhyung Kim <namhyung@...nel.org>,
 Peter Zijlstra <peterz@...radead.org>, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] perf/x86/intel: Use guard() instead of mutex_lock() to
 simplify code

> Using guard(mutex) instead of mutex_lock/mutex_unlock pair. Simplifies the
…
  Use?                          Parentheses behind identifiers?

…
> +++ b/arch/x86/events/intel/core.c
> @@ -6107,18 +6107,16 @@ static ssize_t freeze_on_smi_store(struct device *cdev,
…
>  	cpus_read_lock();
>  	on_each_cpu(flip_smm_bit, &val, 1);
>  	cpus_read_unlock();
> -done:
> -	mutex_unlock(&freeze_on_smi_mutex);
…

How do you think about to apply another lock guard by a subsequent update step?
https://elixir.bootlin.com/linux/v6.17-rc4/source/include/linux/cpuhplock.h#L47

Regards,
Markus