linux-kernel - Re: linux-next: PowerPC WARN_ON_ONCE() after merge of the final tree (tip related)

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: <20100415172421.GB5069@nowhere>
Date:	Thu, 15 Apr 2010 19:24:22 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Stephen Rothwell <sfr@...b.auug.org.au>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-next@...r.kernel.org, linux-kernel@...r.kernel.org,
	ppc-dev <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: linux-next: PowerPC WARN_ON_ONCE() after merge of the final
	tree (tip related)

On Thu, Apr 15, 2010 at 04:03:58PM +0200, Ingo Molnar wrote:
> > 
> > 
> > diff --git a/kernel/lockdep.c b/kernel/lockdep.c
> > index 78325f8..65d4336 100644
> > --- a/kernel/lockdep.c
> > +++ b/kernel/lockdep.c
> > @@ -2298,7 +2298,11 @@ void trace_hardirqs_on_caller(unsigned long ip)
> >  		return;
> >  
> >  	if (unlikely(curr->hardirqs_enabled)) {
> > +		unsigned long flags;
> > +
> > +		raw_local_irq_save(flags);
> >  		debug_atomic_inc(redundant_hardirqs_on);
> > +		raw_local_irq_restore(flags);
> >  		return;
> >  	}
> >  	/* we'll do an OFF -> ON transition: */
> 
> that looks rather ugly. Why not do a raw:
> 
> 	this_cpu_inc(lockdep_stats.redundant_hardirqs_on);
> 
> which basically open-codes debug_atomic_inc(), but without the warning?


There is also no guarantee we are in a non-preemptable section. We can then
also race against another cpu.

I'm not sure what to do.

--
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/