linux-kernel - Re: [PATCH] Fix posix-cpu-timer breakage caused by stale p->last

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]

Message-Id: <1172131299.25076.168.camel@localhost.localdomain>
Date:	Thu, 22 Feb 2007 09:01:39 +0100
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	john stultz <johnstul@...ibm.com>,
	Roman Zippel <zippel@...ux-m68k.org>,
	Mike Galbraith <efault@....de>, balducci@...ts.it,
	LKML <linux-kernel@...r.kernel.org>, Greg KH <greg@...ah.com>
Subject: Re: [PATCH] Fix posix-cpu-timer breakage caused by stale
	p->last_ran value

On Thu, 2007-02-22 at 08:46 +0100, Ingo Molnar wrote:
> * Thomas Gleixner <tglx@...utronix.de> wrote:
> 
> > The problem is that the p->last_ran value is not updated after a 
> > context switch. So a subsequent call to current_sched_time() 
> > calculates with a stale p->last_ran value, i.e. accounts the full 
> > time, which the task was scheduled away.
> > 
> > Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> 
> >  	sched_info_switch(prev, next);
> >  	if (likely(prev != next)) {
> > -		next->timestamp = now;
> > +		next->timestamp = next->last_ran = now;
> 
> ouch! nice catch. Also for v2.6.20.2 i think. 2.6.19 should be 
> unaffected.

Yes, was introduced in 2.6.20 and definitely should hit the stable tree.

	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/