Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751599AbWIXVo7 (ORCPT ); Sun, 24 Sep 2006 17:44:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751600AbWIXVo7 (ORCPT ); Sun, 24 Sep 2006 17:44:59 -0400 Received: from smtp.osdl.org ([65.172.181.4]:59777 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1751580AbWIXVo6 (ORCPT ); Sun, 24 Sep 2006 17:44:58 -0400 Date: Sun, 24 Sep 2006 14:44:40 -0700 From: Andrew Morton To: dipankar@in.ibm.com Cc: linux-kernel@vger.kernel.org, Paul E McKenney , Ingo Molnar Subject: Re: [-mm PATCH] RCU: debug sleep check Message-Id: <20060924144440.ca7e6464.akpm@osdl.org> In-Reply-To: <20060924213508.GG13432@in.ibm.com> References: <20060923152957.GA13432@in.ibm.com> <20060924183509.GB22448@in.ibm.com> <20060924115646.6b5b6482.akpm@osdl.org> <20060924213508.GG13432@in.ibm.com> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-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 Content-Length: 1264 Lines: 31 On Mon, 25 Sep 2006 03:05:08 +0530 Dipankar Sarma wrote: > On Sun, Sep 24, 2006 at 11:56:46AM -0700, Andrew Morton wrote: > > On Mon, 25 Sep 2006 00:05:09 +0530 > > Dipankar Sarma wrote: > > > > > Add a debug check for rcu read-side critical section code calling > > > a function that might sleep which is illegal. The check is enabled only > > > if CONFIG_DEBUG_SPINLOCK_SLEEP is set. > > > > > > > Does this actually change anything? rcu_read_lock is preempt_disable(), and > > might_sleep() already triggers if called inside preempt_disable(). > > It makes a difference if CONFIG_PREEMPT=n. AFAICS, preempt_disable() > is a nop then and rcu needs its own check for sleeping while > in read-side critical section. Right. I think enough people run with CONFIG_PREEMPT=y to make this change rather unnecessary. And if there are developers out there who are testing their code without an effective CONFIG_DEBUG_SPINLOCK_SLEEP, then *that* is what we need to fix, no? - 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/