From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754328Ab2HRWfh (ORCPT ); Sat, 18 Aug 2012 18:35:37 -0400 Received: from mail.linux-iscsi.org ([67.23.28.174]:52047 "EHLO linux-iscsi.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753235Ab2HRWfe (ORCPT ); Sat, 18 Aug 2012 18:35:34 -0400 Subject: Re: [PATCH] tcm_fc: rcu_deref outside rcu lock/unlock section From: "Nicholas A. Bellinger" To: Denis Efremov Cc: "Paul E. McKenney" , Jesper Juhl , target-devel@vger.kernel.org, linux-kernel@vger.kernel.org, ldv-project@ispras.ru, "Rustad, Mark D" , "Patil, Kiran" In-Reply-To: <1345291831-5086-1-git-send-email-yefremov.denis@gmail.com> References: <1345291831-5086-1-git-send-email-yefremov.denis@gmail.com> Content-Type: text/plain; charset="UTF-8" Date: Sat, 18 Aug 2012 15:35:31 -0700 Message-ID: <1345329331.25161.367.camel@haakon2.linux-iscsi.org> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2012-08-18 at 16:10 +0400, Denis Efremov wrote: > Use rcu_dereference_protected in order to prevent lockdep > complaint. Sequel of the patch 863555be > > Found by Linux Driver Verification project (linuxtesting.org). > > Signed-off-by: Denis Efremov > --- > drivers/target/tcm_fc/tfc_sess.c | 4 +++- > 1 files changed, 3 insertions(+), 1 deletions(-) > > diff --git a/drivers/target/tcm_fc/tfc_sess.c b/drivers/target/tcm_fc/tfc_sess.c > index 87901fa..3c9e5b5 100644 > --- a/drivers/target/tcm_fc/tfc_sess.c > +++ b/drivers/target/tcm_fc/tfc_sess.c > @@ -456,7 +456,9 @@ static void ft_prlo(struct fc_rport_priv *rdata) > struct ft_tport *tport; > > mutex_lock(&ft_lport_lock); > - tport = rcu_dereference(rdata->local_port->prov[FC_TYPE_FCP]); > + tport = rcu_dereference_protected(rdata->local_port->prov[FC_TYPE_FCP], > + lockdep_is_held(&ft_lport_lock)); > + > if (!tport) { > mutex_unlock(&ft_lport_lock); > return; This looks OK to silence lockdep. CC'ing MDR + Kiran for good measure here, and will move from target-pending queue -> master with their ACK. Thanks Dennis! --nab