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From: Steven Rostedt <rostedt@goodmis.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	linux-kernel@vger.kernel.org
Subject: Re: bug: ftrace & lockdep badness
Date: Wed, 5 Nov 2008 11:47:52 -0500 (EST)	[thread overview]
Message-ID: <alpine.DEB.1.10.0811051143420.11900@gandalf.stny.rr.com> (raw)
In-Reply-To: <20081105163052.GA28884@elte.hu>


On Wed, 5 Nov 2008, Ingo Molnar wrote:

> 
> * Steven Rostedt <rostedt@goodmis.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


  reply	other threads:[~2008-11-05 16:48 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-11-05 12:37 Heiko Carstens
2008-11-05 13:07 ` Steven Rostedt
2008-11-05 16:04 ` Steven Rostedt
2008-11-05 16:30   ` Ingo Molnar
2008-11-05 16:47     ` Steven Rostedt [this message]
2008-11-05 17:01       ` Frédéric Weisbecker
2008-11-05 17:08       ` Ingo Molnar
2008-11-05 17:13         ` Steven Rostedt

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