linux-kernel - Re: [PATCH] highres: Do not run the TIMER_SOFTIRQ after switching to highres mode

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]

Message-ID: <20070305072518.GB14993@elte.hu>
Date:	Mon, 5 Mar 2007 08:25:18 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Andres Salomon <dilinger@...ian.org>
Cc:	tglx@...utronix.de, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...l.org>
Subject: Re: [PATCH] highres: Do not run the TIMER_SOFTIRQ after switching to	highres mode


* Andres Salomon <dilinger@...ian.org> wrote:

> Thomas Gleixner wrote:
> >>> The question is, how the tick timer gets enqueued in the softirq queue.
> >>> Can you isolate the codepath, where this happens ?
> > 
> > The TIMER_SOFTIRQ runs the hrtimers during bootup until a usable
> > clocksource and clock event sources are registered. The switch to high
> > resolution mode happens inside of the TIMER_SOFTIRQ, but runs the
> > softirq afterwards. That way the tick emulation timer, which was set up
> > in the switch to highres might be executed in the softirq context, which
> > is a BUG. The rbtree has not to be touched by the softirq after the
> > highres switch.
> > 
> 
> And an additional request, just to make it explicit that we should not 
> have any NO_SOFTIRQ callbacks in the tree; BUG out if we encounter 
> such a thing.

please change it to WARN_ON_ONCE()...

'bug out' might mean: 'dead box'/'no resume'/'no bootup'.

	Ingo
-
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/