linux-kernel - Re: [PATCH v2 09/15] timers: Add a warning to usleep_range

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Message-ID: <ece8c4be2d489703fdd6962b16ed573d3b83cde0.camel@perches.com>
Date: Tue, 10 Sep 2024 23:41:06 -0700
From: Joe Perches <joe@...ches.com>
To: Anna-Maria Behnsen <anna-maria@...utronix.de>, Frederic Weisbecker
 <frederic@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, Jonathan
 Corbet <corbet@....net>
Cc: linux-kernel@...r.kernel.org, Len Brown <len.brown@...el.com>, "Rafael
 J. Wysocki" <rafael@...nel.org>, Andy Whitcroft <apw@...onical.com>
Subject: Re: [PATCH v2 09/15] timers: Add a warning to usleep_range_state()
 for wrong order of arguments

On Wed, 2024-09-11 at 07:13 +0200, Anna-Maria Behnsen wrote:
> There is a warning in checkpatch script that triggers, when min and max
> arguments of usleep_range_state() are in reverse order. This check does
> only cover callsites which uses constants. Move this check into the code as
> a WARN_ON_ONCE() to also cover callsites not using constants and get rid of
> it in checkpatch.

I don't disagree that a runtime test is useful
and relatively cost free.

But checkpatch is for patches.

There's no reason as far as I can tell to remove
this source code test.

Why make the test runtime only?


> 
> Cc: Andy Whitcroft <apw@...onical.com>
> Cc: Joe Perches <joe@...ches.com>
> Signed-off-by: Anna-Maria Behnsen <anna-maria@...utronix.de>
> ---
>  kernel/time/sleep_timeout.c | 2 ++
>  scripts/checkpatch.pl       | 4 ----

>  2 files changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/time/sleep_timeout.c b/kernel/time/sleep_timeout.c
> index 21f412350b15..4b805d7e1903 100644
> --- a/kernel/time/sleep_timeout.c
> +++ b/kernel/time/sleep_timeout.c
> @@ -364,6 +364,8 @@ void __sched usleep_range_state(unsigned long min, unsigned long max, unsigned i
>  	ktime_t exp = ktime_add_us(ktime_get(), min);
>  	u64 delta = (u64)(max - min) * NSEC_PER_USEC;
>  
> +	WARN_ON_ONCE(max < min);
> +
>  	for (;;) {
>  		__set_current_state(state);
>  		/* Do not return before the requested sleep time has elapsed */
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 39032224d504..ba3359bdd1fa 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -7088,10 +7088,6 @@ sub process {
>  			if ($min eq $max) {
>  				WARN("USLEEP_RANGE",
>  				     "usleep_range should not use min == max args; see Documentation/timers/timers-howto.rst\n" . "$here\n$stat\n");
> -			} elsif ($min =~ /^\d+$/ && $max =~ /^\d+$/ &&
> -				 $min > $max) {
> -				WARN("USLEEP_RANGE",
> -				     "usleep_range args reversed, use min then max; see Documentation/timers/timers-howto.rst\n" . "$here\n$stat\n");
>  			}
>  		}
>  
>