From mboxrd@z Thu Jan  1 00:00:00 1970
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1756426Ab0AONRK (ORCPT <rfc822;list-kernel77@spinics.net>);
	Fri, 15 Jan 2010 08:17:10 -0500
Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756297Ab0AONRJ
	(ORCPT <rfc822;linux-kernel-outgoing>);
	Fri, 15 Jan 2010 08:17:09 -0500
Received: from bombadil.infradead.org ([18.85.46.34]:42689 "EHLO
	bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1756194Ab0AONRI (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Fri, 15 Jan 2010 08:17:08 -0500
Subject: Re: [RFC] [PATCH 4/7] Uprobes Implementation
From: Peter Zijlstra <peterz@infradead.org>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>, Ingo Molnar <mingo@elte.hu>,
        Arnaldo Carvalho de Melo <acme@infradead.org>,
        Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
        utrace-devel <utrace-devel@redhat.com>, Mark Wielaard <mjw@redhat.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Masami Hiramatsu <mhiramat@redhat.com>,
        Maneesh Soni <maneesh@in.ibm.com>, LKML <linux-kernel@vger.kernel.org>
In-Reply-To: <20100115130802.GC20658@linux.vnet.ibm.com>
References: <20100111122521.22050.3654.sendpatchset@srikar.in.ibm.com>
	 <20100111122553.22050.46895.sendpatchset@srikar.in.ibm.com>
	 <1263467394.4244.291.camel@laptop>
	 <1263509380.4875.35.camel@localhost.localdomain>
	 <1263546632.4244.352.camel@laptop>
	 <20100115102645.GA22640@linux.vnet.ibm.com>
	 <1263551607.4244.379.camel@laptop>
	 <20100115130802.GC20658@linux.vnet.ibm.com>
Content-Type: text/plain; charset="UTF-8"
Date: Fri, 15 Jan 2010 14:16:29 +0100
Message-ID: <1263561389.4244.410.camel@laptop>
Mime-Version: 1.0
X-Mailer: Evolution 2.28.1 
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, 2010-01-15 at 18:38 +0530, Srikar Dronamraju wrote:
> * Peter Zijlstra <peterz@infradead.org> [2010-01-15 11:33:27]:
> 
> > 
> > > Uprobes layer would need to be notified of process life-time events
> > > like fork/clone/exec/exit. 
> > 
> > No so much the process lifetimes as the vma life times are interesting,
> > placing a hook in the vm code to track that isn't too hard, 
> > 
> > > It also needs to know
> > > 	-  when a breakpoint is hit
> > > 	-  stop and resume a thread.
> > 
> > A simple hook in the trap code is done quickly enough, and no reason to
> > stop the thread, its not going anywhere when it traps.
> > 
> > 
> 
> Some of the threads could be executing in the vicinity of the
> breakpoint when it is getting inserted or deleted. Wont we need to
> stop/quiesce those threads?

The easy answer it so use kstopmachine to patch the code, the slightly
more complex would be using something like:

  http://lkml.org/lkml/2010/1/12/300