From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751200AbVHLPmY (ORCPT ); Fri, 12 Aug 2005 11:42:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751201AbVHLPmY (ORCPT ); Fri, 12 Aug 2005 11:42:24 -0400 Received: from e4.ny.us.ibm.com ([32.97.182.144]:36793 "EHLO e4.ny.us.ibm.com") by vger.kernel.org with ESMTP id S1751200AbVHLPmX (ORCPT ); Fri, 12 Aug 2005 11:42:23 -0400 Date: Fri, 12 Aug 2005 08:42:52 -0700 From: "Paul E. McKenney" To: Oleg Nesterov Cc: Ingo Molnar , Dipankar Sarma , linux-kernel@vger.kernel.org Subject: Re: [RFC,PATCH] Use RCU to protect tasklist for unicast signals Message-ID: <20050812154252.GB1297@us.ibm.com> Reply-To: paulmck@us.ibm.com References: <42FB41B5.98314BA5@tv-sign.ru> <20050812015607.GR1300@us.ibm.com> <42FC6305.E7A00C0A@tv-sign.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <42FC6305.E7A00C0A@tv-sign.ru> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 12, 2005 at 12:51:17PM +0400, Oleg Nesterov wrote: > Paul E. McKenney wrote: > > > > --- linux-2.6.13-rc4-realtime-preempt-V0.7.53-01/fs/exec.c 2005-08-11 11:44:55.000000000 -0700 > > +++ linux-2.6.13-rc4-realtime-preempt-V0.7.53-01-tasklistRCU/fs/exec.c 2005-08-11 12:26:45.000000000 -0700 > > [ ... snip ... ] > > @@ -785,11 +787,13 @@ no_thread_group: > > recalc_sigpending(); > > > > + oldsighand->deleted = 1; > > + oldsighand->successor = newsighand; > > I don't think this is correct. > > This ->oldsighand can be shared with another CLONE_SIGHAND > process and will not be deleted, just unshared. > > When the signal is sent to that process we must use ->oldsighand > for locking, not the oldsighand->successor == newsighand. Hmmm... Sounds like I mostly managed to dig myself in deeper here. Back to the drawing board... Thanx, Paul