From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753491Ab3BCSkK (ORCPT ); Sun, 3 Feb 2013 13:40:10 -0500 Received: from e38.co.us.ibm.com ([32.97.110.159]:49520 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753341Ab3BCSkH (ORCPT ); Sun, 3 Feb 2013 13:40:07 -0500 Date: Sun, 3 Feb 2013 10:39:58 -0800 From: "Paul E. McKenney" To: Steven Whitehouse Cc: Dipankar Sarma , linux-kernel@vger.kernel.org, adas@redhat.com, hch@lst.de, npiggin@gmail.com Subject: Re: rcu: fix hlist_bl_set_first_rcu annotation Message-ID: <20130203183958.GO2632@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1359572877.2719.50.camel@menhir> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1359572877.2719.50.camel@menhir> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13020318-5518-0000-0000-00000B3F2EC9 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 30, 2013 at 07:07:57PM +0000, Steven Whitehouse wrote: > > Abhi noticed that we were getting a complaint from the RCU subsystem > about access of an RCU protected list under the write side bit lock. > This patch adds additional annotation to check both the RCU read > lock and the write side bit lock before printing a message. > > Signed-off-by: Steven Whitehouse > Reported-by: Abhijith Das > Tested-by: Abhijith Das Looks plausible to me on first glance, copying Nick Piggin and Christoph Hellwig. If they have no objections, I will queue this. Thanx, Paul > diff --git a/include/linux/list_bl.h b/include/linux/list_bl.h > index 31f9d75..2eb8855 100644 > --- a/include/linux/list_bl.h > +++ b/include/linux/list_bl.h > @@ -125,6 +125,11 @@ static inline void hlist_bl_unlock(struct hlist_bl_head *b) > __bit_spin_unlock(0, (unsigned long *)b); > } > > +static inline bool hlist_bl_is_locked(struct hlist_bl_head *b) > +{ > + return bit_spin_is_locked(0, (unsigned long *)b); > +} > + > /** > * hlist_bl_for_each_entry - iterate over list of given type > * @tpos: the type * to use as a loop cursor. > diff --git a/include/linux/rculist_bl.h b/include/linux/rculist_bl.h > index cf1244f..4f216c5 100644 > --- a/include/linux/rculist_bl.h > +++ b/include/linux/rculist_bl.h > @@ -20,7 +20,7 @@ static inline void hlist_bl_set_first_rcu(struct hlist_bl_head *h, > static inline struct hlist_bl_node *hlist_bl_first_rcu(struct hlist_bl_head *h) > { > return (struct hlist_bl_node *) > - ((unsigned long)rcu_dereference(h->first) & ~LIST_BL_LOCKMASK); > + ((unsigned long)rcu_dereference_check(h->first, hlist_bl_is_locked(h)) & ~LIST_BL_LOCKMASK); > } > > /** > >