linux-kernel - Re: Regression: WARNINGS and lockdep spews in 2.6.38-rc3+ (bisected).

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: <20110203101739.GA1551@zhy>
Date:	Thu, 3 Feb 2011 18:17:39 +0800
From:	Yong Zhang <yong.zhang0@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Nick Bowler <nbowler@...iptictech.com>,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: Regression: WARNINGS and lockdep spews in 2.6.38-rc3+
 (bisected).

On Thu, Feb 03, 2011 at 10:30:40AM +0100, Peter Zijlstra wrote:
> On Thu, 2011-02-03 at 17:12 +0800, Yong Zhang wrote:
> >  #ifdef CONFIG_LOCKDEP
> > +       unsigned long flags;
> > +
> >         local_bh_disable();
> >         lock_map_acquire(&timer->lockdep_map);
> >         lock_map_release(&timer->lockdep_map);
> > -       local_bh_enable();
> > +       /* raw_local_irq_[save|restore] is to protect _local_bh_enable() */
> > +       raw_local_irq_save(flags);
> > +       _local_bh_enable();
> > +       raw_local_irq_restore(flags);
> >  #endif 
> 
> _why_ are you doing the raw_local_irq stuff? That's just weird, and that
> comment isn't helping.

Just to avoid trigger WARN_ON_ONCE(!irqs_disabled()) in __local_bh_enable(),

> 
> Also, calling _local_bh_enable() will leave pending softirqs, not
> particularly nice

Ah, indeed. That's bad.

Now I'm not sure how to work around this issue, because local_bh_enable()
and _local_bh_enable() are not suitable here.

Maybe we can introduce another type of local_bh_enable() in which
waking up ksoftirqd is forced if needed.

Thanks,
Yong
--
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/