Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757275AbWKWJb6 (ORCPT ); Thu, 23 Nov 2006 04:31:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757279AbWKWJb6 (ORCPT ); Thu, 23 Nov 2006 04:31:58 -0500 Received: from smtp-out.google.com ([216.239.33.17]:50915 "EHLO smtp-out.google.com") by vger.kernel.org with ESMTP id S1757275AbWKWJb5 (ORCPT ); Thu, 23 Nov 2006 04:31:57 -0500 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=received:message-id:date:from:to:subject:cc:in-reply-to: mime-version:content-type:content-transfer-encoding: content-disposition:references; b=DZS8y/wvhEEss0ctf1teB4Rhn5875suYAT1I/gar9jmqcDksquEUUpoPPqLroG9hc VfuJMEGNPIV2c9S06GdgQ== Message-ID: <6599ad830611230131w1bf63dc1m1998b55b61579509@mail.gmail.com> Date: Thu, 23 Nov 2006 01:31:47 -0800 From: "Paul Menage" To: "Pavel Emelianov" Subject: Re: [ckrm-tech] [PATCH 4/13] BC: context handling Cc: "Kirill Korotaev" , "Andrew Morton" , ckrm-tech@lists.sourceforge.net, "Linux Kernel Mailing List" , matthltc@us.ibm.com, hch@infradead.org, "Alan Cox" , oleg@tv-sign.ru, devel@openvz.org In-Reply-To: <456567DD.6090703@openvz.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <45535C18.4040000@sw.ru> <45535E11.20207@sw.ru> <6599ad830611222348o1203357tea64fff91edca4f3@mail.gmail.com> <45655D3E.5020702@openvz.org> <6599ad830611230053m7182698cu897abe5d19471aff@mail.gmail.com> <456567DD.6090703@openvz.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 986 Lines: 33 On 11/23/06, Pavel Emelianov wrote: > You mean moving is like this: > > old_bc = task->real_bc; > task->real_bc = new_bc; > cmpxchg(&tsk->exec_bc, old_bc, new_bc); > > ? Then this won't work: > > Initialisation: > current->exec_bc = init_bc; > current->real_bc = init_bc; > ... > IRQ: > current->exec_bc = init_bc; > ... > old_bc = tsk->real_bc; /* init_bc */ > tsk->real_bc = bc1; > cx(tsk->exec_bc, init_bc, bc1); /* ok */ > ... > Here at the middle of an interrupt > we have bc1 set as exec_bc on task > which IS wrong! You could get round that by having a separate "irq_bc" that's never valid for a task not in an interrupt. Paul - 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/