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Date: Sun, 21 Dec 2008 11:00:47 +0100
From: Ingo Molnar <mingo@elte.hu>
To: =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Steven Rostedt <rostedt@goodmis.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] tracing/function-graph-tracer: prevent from hrtimer
	interrupt infinite loop
Message-ID: <20081221100047.GA31074@elte.hu>
References: <4949A2CC.6040209@gmail.com> <20081218103459.GD10513@elte.hu> <alpine.LFD.2.00.0812181136410.3492@localhost.localdomain> <20081218112216.GE14332@elte.hu> <c62985530812181307k4fc35770x3698101b3981879a@mail.gmail.com> <20081218211637.GF24271@elte.hu> <c62985530812181336m6ab39c8ah410dff763bd02d24@mail.gmail.com> <20081218214458.GA30834@elte.hu>
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btw., a graph-tracer buglet i noticed:

  3)               |  perf_counter_task_tick() {
  3)               |    perf_counter_task_sched_out() {
  3)               |      /* c:ffff88049b184000, u:0: 0000000020ca1ab0 + 0000000000000000 = 0000000020ca1ab0
 */
  3)               |      /* sched-out counter ffff88049b184000, state: 0
 */
  3)   5.024 us    |    }
  3)               |    perf_counter_task_sched_in() {
  3)               |      /* c:ffff88049b184000, u:0: 0000000020ca1ab0 + 0000000000000000 = 0000000020ca1ab0
 */
  3)               |      /* sched-in counter ffff88049b184000, state: 1
 */
  3)   2.605 us    |    }
  3)   9.714 us    |  }
  3)               |  perf_counter_task_tick() {

the bug is that the '*/' comment closing text is printed in the next line 
- that's not a linewrap, it happened like this in the trace. 

The reason is that the ftrace_printk did:

	ftrace_printk("c:%p, u:%d: %016Lx + %016Lx = %016Lx\n",

the closing \n is pretty natural - especially for kernel hackers who might 
just turn printk()s into ftrace_printk(), to embedd printouts in function 
traces. So it would be nice if ftrace skipped over \n's when printing them 
out as embedded C comments.

	Ingo