From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263632AbTFYMKV (ORCPT ); Wed, 25 Jun 2003 08:10:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263743AbTFYMKV (ORCPT ); Wed, 25 Jun 2003 08:10:21 -0400 Received: from e33.co.us.ibm.com ([32.97.110.131]:44727 "EHLO e33.co.us.ibm.com") by vger.kernel.org with ESMTP id S263632AbTFYMKS (ORCPT ); Wed, 25 Jun 2003 08:10:18 -0400 Date: Wed, 25 Jun 2003 18:16:33 +0530 From: "Vamsi Krishna S ." To: Andi Kleen Cc: linux-kernel@vger.kernel.org, richard , suparna Subject: Re: [patch] kprobes for 2.5.73 with single-stepping out-of-line Message-ID: <20030625181633.A20678@in.ibm.com> Reply-To: vamsi@in.ibm.com References: <20030624140926.A17908@in.ibm.com.suse.lists.linux.kernel> <20030625161113.A20435@in.ibm.com> <20030625115202.GB9645@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <20030625115202.GB9645@wotan.suse.de>; from ak@suse.de on Wed, Jun 25, 2003 at 01:52:02PM +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 25, 2003 at 01:52:02PM +0200, Andi Kleen wrote: > On Wed, Jun 25, 2003 at 04:11:13PM +0530, Vamsi Krishna S . wrote: > > On Tue, Jun 24, 2003 at 06:01:09PM +0200, Andi Kleen wrote: > > > "Vamsi Krishna S ." writes: > > > > > > > > > > +static struct kprobe *current_kprobe; > > > > > > This global variable is quite unclean. It looks like it is for passing > > > function arguments around. Why is it needed? > > > > > This is used for keeping track of the probe that is currently being > > handled. This information is needed to be kept across a > > trap 3 - singlestep - trap 1. So, we set store the current probe in > > this variable while handling trap 3, for use while handling the > > subsequent trap 1. > > But how can this be SMP safe? Do you hold a lock during all this? > Yes.. in the interests of keeping the locking to a minimum, only one probe can be handled at a time, even on SMP. > -Andi Thanks, Vamsi. -- Vamsi Krishna S. IBM Software Lab, Bangalore. Ph: +91 80 5044959 Internet: vamsi@in.ibm.com