linux-kernel - Re: [PATCH] clocksource, prevent overflow in clocksource

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, 19 Apr 2012 15:18:43 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Prarit Bhargava <prarit@...hat.com>
cc:	John Stultz <john.stultz@...aro.org>, linux-kernel@...r.kernel.org,
	Salman Qazi <sqazi@...gle.com>, stable@...nel.org
Subject: Re: [PATCH] clocksource, prevent overflow in clocksource_cyc2ns

On Thu, 19 Apr 2012, Prarit Bhargava wrote:
> On 04/19/2012 08:52 AM, Thomas Gleixner wrote:
> > On Thu, 19 Apr 2012, Thomas Gleixner wrote:
> > 
> >> On Wed, 18 Apr 2012, John Stultz wrote:
> >>> On 04/18/2012 04:59 PM, Prarit Bhargava wrote:
> >>>>
> 
> >> No. The show_state() part prints into the buffer. But it's not
> >> guaranteed that the buffer is flushed right away. It could be flushed
> >> later as well in a different context. And of course the flush code
> >> runs with interrupts disabled and dumping out a gazillion of lines
> >> over serial will cause the same hickup. Just planting random
> >> touch_watchdog() calls into the code is not the right approach,
> >> really.
> >>
> >> We should think about the reasons why we have interrupts disabled for
> >> so much time. Is that really, really necessary ?
> 
> In the case of the sysrq-t, I would argue that it is.  The whole point behind
> the sysrq-t is that we're capturing the *current* state of the system.  Having
> that output effected by interrupts seems like a bad idea.

Nonsense. The system state can change, while we are dumping it unless
you run on an UP system. irq disable only affects the current CPU
nothing else, and nothing can prevent the other cpus to wake up, run,
exit, fork .....

Thanks,

	tglx


--
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/