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From: "Frédéric Weisbecker" <fweisbec@gmail.com>
To: "Steven Rostedt" <rostedt@goodmis.org>
Cc: "Linux Kernel" <linux-kernel@vger.kernel.org>,
	"Ingo Molnar" <mingo@elte.hu>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Linus Torvalds" <torvalds@linux-foundation.org>
Subject: Re: [PATCH] ftrace: fix current_tracer error return
Date: Tue, 28 Oct 2008 16:35:11 +0100	[thread overview]
Message-ID: <c62985530810280835k66d3ab87qd1783a0135228174@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.1.10.0810281039130.29482@gandalf.stny.rr.com>

2008/10/28 Steven Rostedt <rostedt@goodmis.org>:
>
> The commit (in linux-tip) c2931e05ec5965597cbfb79ad332d4a29aeceb23
>  ( ftrace: return an error when setting a nonexistent tracer )
> added useful code that would error when a bad tracer was written into
> the current_tracer file.
>
> But this had a bug if the amount written was more than the amount read by
> that code. The first iteration would set the tracer correctly, but since
> it did not consume the rest of what was written (usually whitespace), the
> userspace utility would continue to write what was not consumed. This
> second iteration would fail to find a tracer and return -EINVAL. Funny
> thing is that the tracer would have already been set.
>
> This patch just consumes all the data that is written to the file.
>
>
> Signed-off-by: Steven Rostedt <srostedt@redhat.com>



An that corrects the bug when I failed to assign the sched_switch tracer.
Thanks Steven!

Tested-by: Frederic Weisbecker <fweisbec@gmail.com>

  reply	other threads:[~2008-10-28 15:35 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-10-27 23:18 Ftrace doesn't work anymore on latest tip Frédéric Weisbecker
2008-10-27 23:36 ` Steven Rostedt
2008-10-27 23:44   ` Frédéric Weisbecker
2008-10-28  9:02     ` Frédéric Weisbecker
2008-10-28 14:23       ` Steven Rostedt
2008-10-28 14:44       ` [PATCH] ftrace: fix current_tracer error return Steven Rostedt
2008-10-28 15:35         ` Frédéric Weisbecker [this message]
2008-10-28 15:41           ` Steven Rostedt
2008-10-28 18:15             ` Frédéric Weisbecker
2008-10-28 18:32               ` Steven Rostedt
2008-10-29  0:34                 ` Frédéric Weisbecker
2008-10-29  0:55                   ` Steven Rostedt
2008-10-29  1:09                     ` Frédéric Weisbecker
2008-10-29  1:11                       ` Steven Rostedt
2008-10-29  8:35                         ` Ingo Molnar

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