From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>,
LKML <linux-kernel@vger.kernel.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@linux-foundation.org>,
yrl.pp-manager.tt@hitachi.com
Subject: Re: [RFC][PATCH] kprobes: Add separate preempt_disabling for kprobes
Date: Fri, 01 Jul 2011 10:22:09 +0900 [thread overview]
Message-ID: <4E0D2141.4080608@hitachi.com> (raw)
In-Reply-To: <1309470997.12449.614.camel@twins>
(2011/07/01 6:56), Peter Zijlstra wrote:
> On Thu, 2011-06-30 at 11:51 -0400, Steven Rostedt wrote:
>>
>> To solve this, I've added a per_cpu variable called
>> kprobe_preempt_disabled, that is set by the kprobe code. If it is set,
>> the preempt_schedule() will not preempt the code.
Sorry for replying so late :(
> Damn this is ugly. Can we step back and see if we can make the
> requirement for kprobe to disable preemption go away?
As I replied right now, I think we can just eliminate that
disabling preemption code. At least we'd better try it.
I agree with you, introducing this kind of complexity
just for kprobes is not what I want. :(
> Why does it have to do that anyway? Isn't it keeping enough per-task
> state to allow preemption over the single step?
preemption itself must not happen on single stepping, but it seems
impossible to do heavy context switching with setting TF bit...
Thank you,
--
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com
next prev parent reply other threads:[~2011-07-01 1:22 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-30 13:23 [BUG] kprobes crashing because of preempt count Steven Rostedt
2011-06-30 15:51 ` [RFC][PATCH] kprobes: Add separate preempt_disabling for kprobes Steven Rostedt
2011-06-30 16:14 ` Frederic Weisbecker
2011-06-30 16:46 ` Steven Rostedt
2011-06-30 19:40 ` Jason Baron
2011-06-30 19:42 ` Steven Rostedt
2011-06-30 21:56 ` Peter Zijlstra
2011-07-01 1:22 ` Masami Hiramatsu [this message]
2011-07-01 1:38 ` Steven Rostedt
2011-07-01 1:52 ` Masami Hiramatsu
2011-07-01 5:09 ` Masami Hiramatsu
2011-07-01 11:13 ` Masami Hiramatsu
2011-07-01 12:54 ` Steven Rostedt
2011-07-01 12:19 ` Steven Rostedt
2011-07-01 13:15 ` Masami Hiramatsu
2011-07-01 13:14 ` [RFC PATCH -tip ] [BUGFIX] x86: Remove preempt disabling from kprobes Masami Hiramatsu
2011-07-01 13:43 ` Steven Rostedt
2011-07-01 13:53 ` Steven Rostedt
2011-07-03 2:05 ` Masami Hiramatsu
2011-07-02 6:09 ` Ananth N Mavinakayanahalli
2011-07-01 1:12 ` [BUG] kprobes crashing because of preempt count Masami Hiramatsu
2011-07-01 1:33 ` Steven Rostedt
2011-07-01 2:23 ` Masami Hiramatsu
2011-07-01 11:36 ` Ananth N Mavinakayanahalli
2011-07-01 12:01 ` Masami Hiramatsu
2011-07-01 13:03 ` Ananth N Mavinakayanahalli
2011-07-01 13:19 ` Steven Rostedt
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