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From: Ingo Molnar <mingo@elte.hu>
To: "Frédéric 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
Date: Sun, 21 Dec 2008 11:00:47 +0100	[thread overview]
Message-ID: <20081221100047.GA31074@elte.hu> (raw)
In-Reply-To: <20081218214458.GA30834@elte.hu>


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

  parent reply	other threads:[~2008-12-21 10:01 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-12-18  1:09 [PATCH v2] tracing/function-graph-tracer: prevent from hrtimer interrupt infinite loop Frederic Weisbecker
2008-12-18 10:34 ` Ingo Molnar
2008-12-18 10:48   ` Thomas Gleixner
2008-12-18 10:56     ` Frédéric Weisbecker
2008-12-18 11:22     ` Ingo Molnar
2008-12-18 21:07       ` Frédéric Weisbecker
2008-12-18 21:16         ` Ingo Molnar
2008-12-18 21:36           ` Frédéric Weisbecker
2008-12-18 21:44             ` Ingo Molnar
2008-12-18 22:00               ` Frédéric Weisbecker
2008-12-21 10:00               ` Ingo Molnar [this message]
2008-12-21 10:12                 ` Ingo Molnar
2008-12-21 12:21                   ` Frédéric Weisbecker
2008-12-22 10:46                     ` Frédéric Weisbecker
2008-12-18 10:51   ` Frédéric Weisbecker
2008-12-18 11:16     ` Ingo Molnar

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