linux-kernel - Re: [PATCH 2/2][RFC] kselftest: timers: Add adjtick test to validate adjtimex() tick adjustments

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 9 Sep 2015 10:32:43 +0200
From:	Miroslav Lichvar <mlichvar@...hat.com>
To:	John Stultz <john.stultz@...aro.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Nuno Gonçalves <nunojpg@...il.com>,
	Prarit Bhargava <prarit@...hat.com>,
	Richard Cochran <richardcochran@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Shuah Khan <shuahkh@....samsung.com>
Subject: Re: [PATCH 2/2][RFC] kselftest: timers: Add adjtick test to validate
 adjtimex() tick adjustments

On Tue, Sep 08, 2015 at 10:57:06PM -0700, John Stultz wrote:
> Recently an issue was reported that was difficult to detect except
> by tweaking the adjtimex tick value, and noticing how quickly the
> adjustment took to be made:
> 	https://lkml.org/lkml/2015/9/1/488
> 
> Thus this patch introduces a new test which manipulates the adjtimex
> tick value and validates the results are what we expect.

Great!

> +	ppm = ((long long)tickval * MILLION)/10000 - MILLION;

I think this needs to be based on sysconf(_SC_CLK_TCK) or similar,
since the user-space HZ is not 100 on all archs.

> +	for (tick = 9000; tick < 11000; tick += 250)
> +		if (check_tick_adj(tick)) {

This too.

> +	tx1.tick = 10000;
> +	adjtimex(&tx1);

And this too.

-- 
Miroslav Lichvar
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/