From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 17 Sep 2001 20:18:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 17 Sep 2001 20:18:47 -0400 Received: from maynard.mail.mindspring.net ([207.69.200.243]:62504 "EHLO maynard.mail.mindspring.net") by vger.kernel.org with ESMTP id ; Mon, 17 Sep 2001 20:18:32 -0400 Subject: Re: [SMP lock BUG?] Re: Feedback on preemptible kernel patch From: Robert Love To: Manfred Spraul Cc: Pavel Machek , Roger Larsson , linux-kernel@vger.kernel.org, nigel@nrg.org In-Reply-To: <003b01c13fc9$d04a4830$010411ac@local> In-Reply-To: <000901c138bbe151270/mnt/sendme10411ac@local> <1000007070.836.14.camel@phantasy> <001a01c1390262c7f30/mnt/sendme10411ac@local> <20010914091558.A35@toy.ucw.cz> <003b01c13fc9$d04a4830$010411ac@local> Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Evolution/0.13.99+cvs.2001.09.17.07.08 (Preview Release) Date: 17 Sep 2001 20:19:28 -0400 Message-Id: <1000772375.12771.8.camel@phantasy> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2001-09-17 at 18:40, Manfred Spraul wrote: > > is it legal to kmap_atomic(a,b); kmap_atomic(c,d); kunmap_atomic(a,b); > > Yes, that's legal - just think about one kmap_atomic from process > context, and another one in irq context. > > > If so, your patch may need some ounting.... > > Pavel > > I hope ctx_sw_off does internal counting, correct? yes, ctx_sw_off atomically increments a counter and ctx_sw_on atomic_dec_and_test()s it. -- Robert M. Love rml at ufl.edu rml at tech9.net