From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759970AbXHQSyb (ORCPT ); Fri, 17 Aug 2007 14:54:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754512AbXHQSyU (ORCPT ); Fri, 17 Aug 2007 14:54:20 -0400 Received: from smtp2.linux-foundation.org ([207.189.120.14]:41626 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756897AbXHQSyT (ORCPT ); Fri, 17 Aug 2007 14:54:19 -0400 Date: Fri, 17 Aug 2007 11:53:56 -0700 From: Andrew Morton To: paulmck@linux.vnet.ibm.com Cc: bunk@kernel.org, josh@kernel.org, linux-kernel@vger.kernel.org, mingo@elte.hu Subject: Re: [PATCH] Make rcutorture RNG use temporal entropy Message-Id: <20070817115356.cb201e42.akpm@linux-foundation.org> In-Reply-To: <20070816024904.GA5312@linux.vnet.ibm.com> References: <20070816024904.GA5312@linux.vnet.ibm.com> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.6; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 15 Aug 2007 19:49:04 -0700 "Paul E. McKenney" wrote: > Repost of http://lkml.org/lkml/2007/8/10/472 made available by request. > > The locking used by get_random_bytes() can conflict with the > preempt_disable() and synchronize_sched() form of RCU. This patch changes > rcutorture's RNG to gather entropy from the new cpu_clock() interface > (relying on interrupts, preemption, daemons, and rcutorture's reader > thread's rock-bottom scheduling priority to provide useful entropy), > and also adds and EXPORT_SYMBOL_GPL() to make that interface available > to GPLed kernel modules such as rcutorture. > > Passes several hours of rcutorture. Please explain what "conflict with" means so that I can work out if this is a needed-in-2.6.23 change, thanks.