From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752549AbbCYNtl (ORCPT ); Wed, 25 Mar 2015 09:49:41 -0400 Received: from e38.co.us.ibm.com ([32.97.110.159]:34102 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751128AbbCYNti (ORCPT ); Wed, 25 Mar 2015 09:49:38 -0400 Date: Wed, 25 Mar 2015 06:49:29 -0700 From: "Paul E. McKenney" To: Ying Xue Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] rculist: Fix another sparse warning Message-ID: <20150325134929.GY5718@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1427258618-32085-1-git-send-email-ying.xue@windriver.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1427258618-32085-1-git-send-email-ying.xue@windriver.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15032513-0029-0000-0000-000008BC7009 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 25, 2015 at 12:43:38PM +0800, Ying Xue wrote: > This fixes the following sparse warnings: > > make C=1 CF=-D__CHECK_ENDIAN__ net/tipc/name_table.o > net/tipc/name_table.c:977:17: error: incompatible types in comparison expression (different address spaces) > net/tipc/name_table.c:977:17: error: incompatible types in comparison expression (different address spaces) > > To silence these spare complaints, an RCU annotation should be added to > "next" pointer of hlist_node structure through hlist_next_rcu() macro > when iterating over a hlist with hlist_for_each_entry_from_rcu(). > > Signed-off-by: Ying Xue If hlist_for_each_entry_from_rcu() is to use rcu_dereference_bh(), then it needs to be named hlist_for_each_entry_from_rcu_bh(). If we want to retain the generic nature, rcu_dereference_raw() would work. (Otherwise, we would get splats if this was used under rcu_read_lock() rather than rcu_read_lock_bh().) Thanx, Paul > --- > include/linux/rculist.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/include/linux/rculist.h b/include/linux/rculist.h > index a18b16f..18a3f15 100644 > --- a/include/linux/rculist.h > +++ b/include/linux/rculist.h > @@ -549,8 +549,8 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n, > */ > #define hlist_for_each_entry_from_rcu(pos, member) \ > for (; pos; \ > - pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\ > - typeof(*(pos)), member)) > + pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \ > + &(pos)->member)), typeof(*(pos)), member)) > > #endif /* __KERNEL__ */ > #endif > -- > 1.7.9.5 >