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Date: Mon, 3 Nov 2008 11:10:27 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
       Peter Zijlstra <peterz@infradead.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH -v3] ring-buffer: add paranoid checks for loops
Message-ID: <20081103101027.GG13671@elte.hu>
References: <alpine.DEB.1.10.0810291439460.13214@gandalf.stny.rr.com> <20081030184552.GC17822@elte.hu> <alpine.DEB.1.10.0810302314460.26352@gandalf.stny.rr.com> <20081031093804.GF30317@elte.hu> <alpine.DEB.1.10.0810310956240.13290@gandalf.stny.rr.com>
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* Steven Rostedt <rostedt@goodmis.org> wrote:

> [
>   Changes from v2:
> 
>    Applied Ingo's comments:
> 
>      Rephrased one of the comments.
> 
>      Renamed the "paranoid" variable into "nr_loops".
> ]
> 
> While writing a new tracer, I had a bug where I caused the ring-buffer
> to recurse in a bad way. The bug was with the tracer I was writing
> and not the ring-buffer itself. But it took a long time to find the
> problem.
> 
> This patch adds paranoid checks into the ring-buffer infrastructure
> that will catch bugs of this nature.
> 
> Note: I put the bug back in the tracer and this patch showed the error
>       nicely and prevented the lockup.
> 
> Signed-off-by: Steven Rostedt <srostedt@redhat.com>
> ---
>  kernel/trace/ring_buffer.c |   56 +++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 56 insertions(+)

applied to tip/tracing/urgent, thanks Steve!

	Ingo