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From: Ingo Molnar <mingo@elte.hu>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/4] tracing/branch-tracer: Fix a trace recursion on branch tracer
Date: Sun, 16 Nov 2008 07:22:13 +0100	[thread overview]
Message-ID: <20081116062213.GA32215@elte.hu> (raw)
In-Reply-To: <491FA8C8.1040905@gmail.com>


* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> Impact: Make the branch tracer use raw irq save/restore
> 
> When the branch tracer inserts an event through 
> probe_likely_condition(), it calls local_irq_save() and then results 
> in a trace recursion.
> 
> local_irq_save() -> trace_hardirqs_off() -> trace_hardirqs_off_caller()
> 	-> unlikely()
> 
> The trace_branch.c file is protected by DISABLE_BRANCH_PROFILING but 
> that doesn't prevent from external call to functions that use 
> unlikely().
> 
> My box crashed each time I tried to set this tracer (sudden and hard 
> reboot).

So this patch fixes that problem, or are there other problems left?

	Ingo

  reply	other threads:[~2008-11-16  6:22 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-11-16  4:59 [PATCH 3/4] tracing/branch-tracer: Fix a trace recursion on branch tracer Frederic Weisbecker
2008-11-16  6:22 ` Ingo Molnar [this message]
2008-11-16  6:32   ` Frédéric Weisbecker
2008-11-16  6:49     ` Ingo Molnar
2008-11-16 14:01       ` Frédéric Weisbecker
2008-11-16 22:10         ` Jonathan Corbet
2008-11-17 11:30           ` Ingo Molnar

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