linux-kernel - Re: [PATCH 3/3] tracing: Check cpu file on tracing

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Message-ID: <1365554787.25498.88.camel@gandalf.local.home>
Date:	Tue, 09 Apr 2013 20:46:27 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Namhyung Kim <namhyung.kim@....com>
Cc:	Namhyung Kim <namhyung@...nel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] tracing: Check cpu file on tracing_release()

On Wed, 2013-04-10 at 09:36 +0900, Namhyung Kim wrote:

> You meant iter->cpu_file != RING_BUFFER_ALL_CPUS case, right?

Yep.

> 
> So why bother trying to check other cpus then?

Because it's a very slow path (closing a file), and it keeps the code
simpler and more condense.

We could add your change for consistency, but right now, its very low
priority.

But looking at the code, I do see a clean up that looks like it would be
worth updating. If the ring_buffer_read_prepare() fails, we should
probably let the user know, instead of succeeding and then having no
output.

Looks like all users of the buffer_iter[cpu] will fail quietly if it is
NULL, thus it's not a problem with crashing the kernel.

-- Steve

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