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Message-ID: <9de4fb8fa1223fc61d6d8d8c41066eea3963c12e.camel@perches.com>
Subject: Re: [PATCH] checkpatch: Warn about data_race() without comment
From:   Joe Perches <joe@perches.com>
To:     Marco Elver <elver@google.com>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     paulmck@kernel.org, dvyukov@google.com, glider@google.com,
        andreyknvl@google.com, kasan-dev@googlegroups.com,
        linux-kernel@vger.kernel.org, apw@canonical.com,
        Will Deacon <will@kernel.org>
Date:   Wed, 01 Apr 2020 08:17:52 -0700
In-Reply-To: <20200401101714.44781-1-elver@google.com>
References: <20200401101714.44781-1-elver@google.com>
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On Wed, 2020-04-01 at 12:17 +0200, Marco Elver wrote:
> Warn about applications of data_race() without a comment, to encourage
> documenting the reasoning behind why it was deemed safe.
[]
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -5833,6 +5833,14 @@ sub process {
>  			}
>  		}
>  
> +# check for data_race without a comment.
> +		if ($line =~ /\bdata_race\s*\(/) {
> +			if (!ctx_has_comment($first_line, $linenr)) {
> +				WARN("DATA_RACE",
> +				     "data_race without comment\n" . $herecurr);
> +			}
> +		}
> +
>  # check for smp_read_barrier_depends and read_barrier_depends
>  		if (!$file && $line =~ /\b(smp_|)read_barrier_depends\s*\(/) {
>  			WARN("READ_BARRIER_DEPENDS",

Sensible enough but it looks like ctx_has_comment should
be updated to allow c99 comments too, but that should be
a separate change from this patch.

Otherwise, this style emits a message:

WARNING: data_race without comment
#135: FILE: kernel/rcu/tasks.h:135:
+	int i = data_race(rtp->gp_state); // Let KCSAN detect update races