From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id B6F188D0039 for ; Tue, 15 Mar 2011 18:42:43 -0400 (EDT) Received: by wwb28 with SMTP id 28so1177627wwb.26 for ; Tue, 15 Mar 2011 15:42:40 -0700 (PDT) Subject: Re: [PATCH v2 2.6.38-rc8-tip 4/20] 4: uprobes: Adding and remove a uprobe in a rb tree. From: Eric Dumazet In-Reply-To: <1300218499.2250.12.camel@laptop> References: <20110314133403.27435.7901.sendpatchset@localhost6.localdomain6> <20110314133444.27435.50684.sendpatchset@localhost6.localdomain6> <20110315173041.GB24254@linux.vnet.ibm.com> <1300218499.2250.12.camel@laptop> Content-Type: text/plain; charset="UTF-8" Date: Tue, 15 Mar 2011 23:42:24 +0100 Message-ID: <1300228944.2565.19.camel@edumazet-laptop> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: Thomas Gleixner , Srikar Dronamraju , Ingo Molnar , Steven Rostedt , Linux-mm , Arnaldo Carvalho de Melo , Linus Torvalds , Masami Hiramatsu , Christoph Hellwig , Ananth N Mavinakayanahalli , Andi Kleen , Oleg Nesterov , Andrew Morton , Jim Keniston , Roland McGrath , SystemTap , LKML , "Paul E. McKenney" Le mardi 15 mars 2011 A 20:48 +0100, Peter Zijlstra a A(C)crit : > On Tue, 2011-03-15 at 20:22 +0100, Thomas Gleixner wrote: > > I am not sure if its a good idea to walk the tree > > > as and when the tree is changing either because of a insertion or > > > deletion of a probe. > > > > I know that you cannot walk the tree lockless except you would use > > some rcu based container for your probes. > > You can in fact combine a seqlock, rb-trees and RCU to do lockless > walks. > > https://lkml.org/lkml/2010/10/20/160 > > and > > https://lkml.org/lkml/2010/10/20/437 > > But doing that would be an optimization best done once we get all this > working nicely. > We have such schem in net/ipv4/inetpeer.c function inet_getpeer() (using a seqlock on latest net-next-2.6 tree), but we added a counter to make sure a reader could not enter an infinite loop while traversing tree (AVL tree in inetpeer case). -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org