From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757618Ab1DHQkQ (ORCPT ); Fri, 8 Apr 2011 12:40:16 -0400 Received: from e8.ny.us.ibm.com ([32.97.182.138]:40384 "EHLO e8.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757012Ab1DHQkN (ORCPT ); Fri, 8 Apr 2011 12:40:13 -0400 Date: Fri, 8 Apr 2011 09:39:04 -0700 From: "Paul E. McKenney" To: Amerigo Wang Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Mel Gorman , Minchan Kim , KAMEZAWA Hiroyuki , KOSAKI Motohiro Subject: Re: [Patch v2] rcu: update the CONFIG logic in include/linux/pagemap.h Message-ID: <20110408163904.GD2277@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1302071569-23217-1-git-send-email-amwang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1302071569-23217-1-git-send-email-amwang@redhat.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 06, 2011 at 02:32:48PM +0800, Amerigo Wang wrote: > TREE_RCU depends on !PREEMPT && SMP, when !CONFIG_SMP is true, CONFIG_TREE_RCU > will be false, thus "!defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)" > is always false. > > Paul suggested to update the logic to > !defined(CONFIG_SMP) && defined(CONFIG_TREE_PREEMPT_RCU). Hello, Amerigo, Thank you for keeping on top of this one! But how does this patch handle the #else clauses? Thanx, Paul > Cc: Paul E. McKenney > Signed-off-by: WANG Cong > > --- > include/linux/pagemap.h | 9 +++------ > 1 files changed, 3 insertions(+), 6 deletions(-) > > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > index c119506..a296d7c 100644 > --- a/include/linux/pagemap.h > +++ b/include/linux/pagemap.h > @@ -133,10 +133,9 @@ static inline int page_cache_get_speculative(struct page *page) > { > VM_BUG_ON(in_interrupt()); > > -#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU) > -# ifdef CONFIG_PREEMPT > +#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_PREEMPT_RCU) > + /* Must have CONFIG_PREEMPT here, implied by CONFIG_TREE_PREEMPT_RCU. */ > VM_BUG_ON(!in_atomic()); > -# endif > /* > * Preempt must be disabled here - we rely on rcu_read_lock doing > * this for us. > @@ -171,10 +170,8 @@ static inline int page_cache_add_speculative(struct page *page, int count) > { > VM_BUG_ON(in_interrupt()); > > -#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU) > -# ifdef CONFIG_PREEMPT > +#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_PREEMPT_RCU) > VM_BUG_ON(!in_atomic()); > -# endif > VM_BUG_ON(page_count(page) == 0); > atomic_add(count, &page->_count); >