Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757010AbZLNTpM (ORCPT ); Mon, 14 Dec 2009 14:45:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755585AbZLNTpK (ORCPT ); Mon, 14 Dec 2009 14:45:10 -0500 Received: from mx1.redhat.com ([209.132.183.28]:16873 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755182AbZLNTpI (ORCPT ); Mon, 14 Dec 2009 14:45:08 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: Roland McGrath To: Oleg Nesterov X-Fcc: ~/Mail/utrace Cc: Peter Zijlstra , Alexey Dobriyan , Ananth Mavinakayanahalli , Christoph Hellwig , "Frank Ch. Eigler" , Ingo Molnar , linux-kernel@vger.kernel.org, utrace-devel@redhat.com Subject: Re: [RFC,PATCH 14/14] utrace core In-Reply-To: Oleg Nesterov's message of Monday, 14 December 2009 18:03:27 +0100 <20091214170327.GA7666@redhat.com> References: <20091124200220.GA5828@redhat.com> <1259697242.1697.1075.camel@laptop> <20091214002533.3052519@magilla.sf.frob.com> <20091214170327.GA7666@redhat.com> Emacs: because extension languages should come with the editor built in. Message-Id: <20091214194441.4D6BFE24E@magilla.sf.frob.com> Date: Mon, 14 Dec 2009 11:44:41 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1019 Lines: 31 > Yes, I think this is correct. It is fine to miss ->pending_attach == T, > and in any case the new attacher can come right after the check, even > if it was checked under utrace->lock. Right. > It is important that the tracee can't miss, say, UTRACE_REPORT request > (as you already explained), and every time the tracee clears ->resume > it calls splice_attaching(). Right. > > In the stopped cases, there are lots of locks and barriers and things > > after resuming. (Oleg?) > > Every time the tracee resumes after TASK_TRACED it uses utrace->lock > to synchronize with utrace_control/etc, it must see any changes. And TASK_STOPPED? Please send me patches to add whatever comments would make all this clear enough to Peter when reading the code. Thanks, Roland -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/