From: Masami Hiramatsu <mhiramat@redhat.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
lkml <linux-kernel@vger.kernel.org>,
systemtap <systemtap@sources.redhat.com>,
DLE <dle-develop@lists.sourceforge.net>,
Jim Keniston <jkenisto@us.ibm.com>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Christoph Hellwig <hch@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Anders Kaseorg <andersk@ksplice.com>,
Tim Abbott <tabbott@ksplice.com>,
Andi Kleen <andi@firstfloor.org>, Jason Baron <jbaron@redhat.com>,
Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Subject: Re: [PATCH -tip v5 03/10] kprobes: Introduce kprobes jump optimization
Date: Tue, 24 Nov 2009 16:15:05 -0500 [thread overview]
Message-ID: <4B0C4CD9.3010603@redhat.com> (raw)
In-Reply-To: <20091124194524.GA5071@nowhere>
Frederic Weisbecker wrote:
> On Tue, Nov 24, 2009 at 10:34:08AM -0500, Masami Hiramatsu wrote:
>>> And this comment doesn't tell us much what this brings us.
>>> The changelog tells it stands to avoid a text_mutex deadlock.
>>> I'm not sure why we would deadlock without it.
>>
>> As Mathieu and I discussed on LKML (http://lkml.org/lkml/2009/11/21/187)
>> text_mutex will be locked on the way of cpu-hotplug.
>> Since kprobes locks text_mutex too and stop_machine() refers online_cpus,
>> it will cause a dead-lock. So, I decided to use get_online_cpus() to
>> locking hotplug while optimizing/unoptimizng.
>
>
> Ah ok :)
> Could you add a comment in the code that explains it?
Sure, of course :-)
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com
next prev parent reply other threads:[~2009-11-24 21:18 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-23 23:21 [PATCH -tip v5 00/10] kprobes: Kprobes jump optimization support Masami Hiramatsu
2009-11-23 23:21 ` [PATCH -tip v5 01/10] kprobes/x86: Cleanup RELATIVEJUMP_INSTRUCTION to RELATIVEJUMP_OPCODE Masami Hiramatsu
2009-11-23 23:21 ` [PATCH -tip v5 02/10] kprobes: Introduce generic insn_slot framework Masami Hiramatsu
2009-11-23 23:21 ` [PATCH -tip v5 03/10] kprobes: Introduce kprobes jump optimization Masami Hiramatsu
2009-11-24 2:44 ` Frederic Weisbecker
2009-11-24 3:31 ` Frederic Weisbecker
2009-11-24 15:34 ` Masami Hiramatsu
2009-11-24 20:14 ` Frederic Weisbecker
2009-11-24 20:59 ` Masami Hiramatsu
2009-11-25 21:08 ` Steven Rostedt
2009-11-25 21:30 ` Masami Hiramatsu
2009-11-24 21:08 ` H. Peter Anvin
2009-11-24 15:34 ` Masami Hiramatsu
2009-11-24 19:45 ` Frederic Weisbecker
2009-11-24 21:15 ` Masami Hiramatsu [this message]
2009-11-23 23:21 ` [PATCH -tip v5 04/10] kprobes: Jump optimization sysctl interface Masami Hiramatsu
2009-11-23 23:21 ` [PATCH -tip v5 05/10] kprobes/x86: Boost probes when reentering Masami Hiramatsu
2009-11-23 23:22 ` [PATCH -tip v5 06/10] kprobes/x86: Cleanup save/restore registers Masami Hiramatsu
2009-11-24 2:51 ` Frederic Weisbecker
2009-11-24 15:39 ` Masami Hiramatsu
2009-11-24 20:19 ` Frederic Weisbecker
2009-11-24 15:40 ` Frank Ch. Eigler
2009-11-24 20:20 ` Frederic Weisbecker
2009-11-23 23:22 ` [PATCH -tip v5 07/10] kprobes/x86: Support kprobes jump optimization on x86 Masami Hiramatsu
2009-11-24 3:14 ` Frederic Weisbecker
2009-11-24 16:27 ` Jason Baron
2009-11-24 17:46 ` Masami Hiramatsu
2009-11-25 16:12 ` Masami Hiramatsu
2009-11-24 16:35 ` H. Peter Anvin
2009-11-24 17:00 ` Masami Hiramatsu
2009-11-23 23:22 ` [PATCH -tip v5 08/10] kprobes: Add documents of jump optimization Masami Hiramatsu
2009-11-23 23:22 ` [PATCH -tip v5 09/10] [RFC] x86: Introduce generic jump patching without stop_machine Masami Hiramatsu
2009-11-23 23:22 ` [PATCH -tip v5 10/10] [RFC] kprobes/x86: Use text_poke_fixup() for jump optimization Masami Hiramatsu
2009-11-24 2:03 ` [PATCH -tip v5 00/10] kprobes: Kprobes jump optimization support Frederic Weisbecker
2009-11-24 3:20 ` Frederic Weisbecker
2009-11-24 7:52 ` Ingo Molnar
2009-11-24 16:06 ` Masami Hiramatsu
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