linux-kernel - Re: In many cases softlockup can not be reported after disabling IRQ for long time

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 for Android: free password hash cracker in your pocket

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

Date:	Thu, 2 Feb 2012 08:43:50 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	TAO HU <tghk48@...orola.com>
Cc:	Don Zickus <dzickus@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	linux-omap <linux-omap@...r.kernel.org>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: In many cases softlockup can not be reported after disabling
	IRQ for long time

.sdrawkcab esra s'ti ,tsop pot t'noD

(Don't top post, it's arse backwards.)

On Thu, Feb 02, 2012 at 04:17:02PM +0800, TAO HU wrote:
> My concern is not actually that the softlockup could not be reported
> while the IRQ is disabled.
> What bothering me is that even AFTER re-enable the IRQ, it will not
> give warning in many cases.

That's already been explained.

softlockups are detected by time passing.  Time can't properly advance
with interrupts disabled, as the backing counter (assuming you're using
the clocksource and clockevent stuff) could wrap.  If it wraps, the
systems idea of time which has passed will be incorrect.

So, if interrupts are disabled for a long period, the system loses track
of time, and therefore can't know how long the system has been blocked for.
--
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/