linux-kernel - Re: [PATCH v2] checkpatch: warn about direct use of send_sig_info and force_sig

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Message-ID: <2bea96ba2525c31b18185f51fffea2d2052aa8a0.camel@perches.com>
Date:   Thu, 06 May 2021 14:41:31 -0700
From:   Joe Perches <joe@...ches.com>
To:     Marco Elver <elver@...gle.com>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        Dwaipayan Ray <dwaipayanray1@...il.com>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        Andy Whitcroft <apw@...onical.com>,
        Lukas Bulwahn <lukas.bulwahn@...il.com>
Subject: Re: [PATCH v2] checkpatch: warn about direct use of send_sig_info
 and force_sig_info

On Thu, 2021-05-06 at 17:22 +0200, Marco Elver wrote:
> Setting up siginfo and using send_sig_info() or force_sig_info()
> directly is discouraged. Instead, new code wanting to generate signals
> should use the appropriate helper specific to the signal.
> 
> Eric mentioned that he'd like to make these static at some point, but
> until that can happen, let's try to avoid introducing new users of them.
[]
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -7153,6 +7153,12 @@ sub process {
>  			     "Where possible, use lockdep_assert_held instead of assertions based on spin_is_locked\n" . $herecurr);
>  		}
>  
> 
> +# check for direct use of send_sig_info(), force_sig_info()
> +		if ($line =~ /\b((?:force|send)_sig_info)\(/) {

You want to be able to find uses like 'force_sig_info (<foo>...'
so you should add a \s* after the capture group.
And it's probably simpler and more readable to use
		if ($sline =~ /\b(force_sig_info|send_sig_info)\s*\(/) {
instead of the more complex regex

(sline is stripped of comments, $line is not)

> +			WARN("USE_SIGINFO_HELPER",
> +			     "Where possible, avoid using '$1' directly and use a signal-specific helper setting required siginfo fields (see include/linux/sched/signal.h).\n" . $herecurr);

A rather long and complex sentence.
How about
	"Prefer signal-specific helpers over use of '$1' (see: include/linux/sched/signal.h)\n"

And in that signal.h file, there's no obvious reference to
these signal-specific helpers.  Is there a better reference
in the Documentation/ tree?