linux-kernel - Re: bug: ftrace & lockdep badness

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: <alpine.DEB.1.10.0811051143420.11900@gandalf.stny.rr.com>
Date:	Wed, 5 Nov 2008 11:47:52 -0500 (EST)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Ingo Molnar <mingo@...e.hu>
cc:	Heiko Carstens <heiko.carstens@...ibm.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	linux-kernel@...r.kernel.org
Subject: Re: bug: ftrace & lockdep badness

On Wed, 5 Nov 2008, Ingo Molnar wrote:

> 
> * Steven Rostedt <rostedt@...dmis.org> wrote:
> 
> > This is the type of problems we deal with when we have the tracer 
> > tracing lockdep code at the same time the lockdep code is checking 
> > the tracer.
> 
> ok ... you are right, i guess we need to go back to raw locks after 
> all?

I do like the fact that lockdep checks it too. But there's times that we 
can not do that.

Perhaps we can do something in between.

Make a rb_spin_lock macro inside ring_buffer.c that can be either a 
spin_lock or a raw_spin_lock.  There are some tracers that must have this 
as a raw (function trace, irqsoff and preemptoff), but the rest should be 
fine. We can make it where the rb_spin_lock is a raw lock when any of 
those three tracers are configured, and make it into a normal lock when 
they are not.

This way we can still test the integrity of the ring_buffer for other 
tracers. We just need to be careful when we are using function tracing or 
irqs/preempt off tracing. But we need to be careful with those anyway.

-- Steve

--
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/