linux-kernel - Re: [patch] sched: remove __resched_legal() and fix cond_resched

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] [day] [month] [year] [list]

Date:	Wed, 27 Dec 2006 12:16:19 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
Cc:	Fabio Comolli <fabio.comolli@...il.com>,
	kernel list <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...l.org>,
	Andrew Morton <akpm@...l.org>
Subject: Re: [patch] sched: remove __resched_legal() and fix cond_resched_softirq()


* OGAWA Hirofumi <hirofumi@...l.parknet.co.jp> wrote:

> > i found another bug and realized that the whole __resched_legal() 
> > approach is fundamentally wrong! The patch below fixes this.
> 
> Hmm.. but the path seems,
> 
> -> cond_resched()
>   -> if (__resched_legal())		/* preempt_count == 0 */
>     -> __cond_resched()			/* preempt_count == 0x10000000 */
>       -> schedule()
>         [...]
>         -> cond_resched()
>           -> if (__resched_legal())	/* preempt_count == 0x10000000 */
>             -> __cond_resched()		/* preempt_count == 0x20000000 */
>               -> schedule()             /* warning */
> 
> Where is it prevented? Or warning is just wrong?

this should be handled by the second version of the patch i sent out 
yesterday. When we have PREEMPT_ACTIVE set, no schedule() call is legal.

	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/