linux-kernel - Re: [PATCH 0/3 v2] [GIT PULL][3.9] tracing: Fixes with flags and latency tracers

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Date:	Mon, 18 Mar 2013 09:49:13 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCH 0/3 v2] [GIT PULL][3.9] tracing: Fixes with flags and
 latency tracers


* Steven Rostedt <rostedt@...dmis.org> wrote:

> 
> Ingo,
> 
> Here's take two of the last patch series I sent. The only difference
> with this series is that I encapsulate the max_tr reference with
> the #ifdef CONFIG_TRACER_MAX_TRACE. Other than that, it's the same.
> 
> Here's the recap:
> 
> The first patch fixes a long standing bug where the changing of
> the trace options has absolutely no protection against multiple
> changers. Luckily, this is something that requires human (root)
> action, and is usually performed by a single individual. But as
> scripts are starting to become more active, this bug is bound to
> be triggered.
> 
> The second patch is a bug where the setting of the overwrite flag
> can cause the max and normal buffers to get out of sync. This
> is more predomitinant with the 3.9 snapshot feature, but still
> has an affect on the latency tracers. Which bring us to the third
> patch.
> 
> The third patch I found out that disabling overwrite to the buffers
> screws with the latency tracers. If the buffer is in produce consumer
> mode, the irqsoff tracer and friends wont show any output at all.
> This was a bit frustrating to figure out.
> 
> Hopefully this time it's good.
> 
> Thanks,
> 
> -- Steve
> 
> Please pull the latest tip/perf/urgent-2 tree, which can be found at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
> tip/perf/urgent-2
> 
> Head SHA1: 613f04a0f51e6e68ac6fe571ab79da3c0a5eb4da
> 
> 
> Steven Rostedt (Red Hat) (3):
>       tracing: Protect tracer flags with trace_types_lock
>       tracing: Keep overwrite in sync between regular and snapshot buffers
>       tracing: Prevent buffer overwrite disabled for latency tracers
> 
> ----
>  kernel/trace/trace.c              |   56 +++++++++++++++++++++++++++++--------
>  kernel/trace/trace.h              |    6 ++++
>  kernel/trace/trace_irqsoff.c      |   19 +++++++++----
>  kernel/trace/trace_sched_wakeup.c |   18 ++++++++----
>  4 files changed, 78 insertions(+), 21 deletions(-)

Pulled, thanks Steve!

	Ingo
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