linux-kernel - Re: [RFC PATCH 1/1] checkpatch: Add warning for msleep with durations suitable for ssleep

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Date: Sat, 09 Mar 2024 11:47:13 -0800
From: Joe Perches <joe@...ches.com>
To: Li Chen <me@...ux.beauty>, Andy Whitcroft <apw@...onical.com>, Dwaipayan
	Ray <dwaipayanray1@...il.com>, Lukas Bulwahn <lukas.bulwahn@...il.com>, 
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 1/1] checkpatch: Add warning for msleep with
 durations suitable for ssleep

On Tue, 2024-03-05 at 23:47 +0800, Li Chen wrote:
> From: Li Chen <chenl311@...natelecom.cn>
[]
> Warn when msleep(x000); can be replaced with ssleep(x);

While I don't really see the point as msleep is trivial
to read and ssleep is just msleep * 1000 and there are
already 3:1 more msleep(n*1000) uses than there are ssleep(n)

$ git grep -P '\bmsleep\s*\(\s*\d+000\s*\)' | wc -l
267
$ git grep -P '\bssleep\s*\(\s*\d+\s*\)' | wc -l
89

And about the patch itself:

> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -6599,6 +6599,16 @@ sub process {
>  			}
>  		}
>  
> +# warn about msleep() calls with durations that should use ssleep()
> +if ($line =~ /\bmsleep\s*\((\d+)\);/) {

This indentation is incorrect.
And this would be more sensible using
		if ($line =~ /\bmsleep\s*\(\s*(\d+)000\s*\)/) {

to avoid the extra tests below

> +    my $ms_duration = $1;
> +    if ($ms_duration >= 1000 && ($ms_duration % 1000) == 0) {
> +        my $ss_duration = $ms_duration / 1000;
> +        WARN("SSLEEP",
> +             "Prefer ssleep($ss_duration) over msleep($ms_duration);\n"  $herecurr);

And please add a $fix to this so:

		if ($line =~ /\bmsleep\s*\(\s*(\d+)000\s*\)/) {
			$secs = $1;
			if (WARN("SSLEEP",
				 "Prefer ssleep($secs) over msleep(${secs}000\n") &&
			    $fix) {
				$fixed[$fixlinenr] =~ s/\bmsleep\s*\(\s*${secs}000\s*\)/ssleep($secs)/;
			}