From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755725AbeEAORF (ORCPT ); Tue, 1 May 2018 10:17:05 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:41100 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753072AbeEAORE (ORCPT ); Tue, 1 May 2018 10:17:04 -0400 Date: Tue, 1 May 2018 07:18:17 -0700 From: "Paul E. McKenney" To: Joel Fernandes Cc: linux-kernel@vger.kernel.org, Steven Rostedt , Peter Zilstra , Ingo Molnar , Mathieu Desnoyers , Tom Zanussi , Namhyung Kim , Thomas Glexiner , Boqun Feng , Frederic Weisbecker , Randy Dunlap , Masami Hiramatsu , Fenguang Wu , Baohong Liu , Vedang Patel , kernel-team@android.com Subject: Re: [PATCH RFC v5 3/6] srcu: Add notrace variant of srcu_dereference Reply-To: paulmck@linux.vnet.ibm.com References: <20180501014204.67548-1-joelaf@google.com> <20180501014204.67548-4-joelaf@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180501014204.67548-4-joelaf@google.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18050114-0056-0000-0000-00000447E1CD X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008956; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000257; SDB=6.01025961; UDB=6.00523953; IPR=6.00805192; MB=3.00020880; MTD=3.00000008; XFM=3.00000015; UTC=2018-05-01 14:17:01 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18050114-0057-0000-0000-0000088BE797 Message-Id: <20180501141817.GE26088@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-05-01_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1805010143 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 30, 2018 at 06:42:01PM -0700, Joel Fernandes wrote: > In this series, we are making lockdep use an rcuidle tracepoint. For > this reason we need a notrace variant of srcu_dereference since > otherwise we get lockdep splats since lockdep hooks may not have run > yet. This patch adds the needed variant. > > Cc: Steven Rostedt > Cc: Peter Zilstra > Cc: Ingo Molnar > Cc: Mathieu Desnoyers > Cc: Tom Zanussi > Cc: Namhyung Kim > Cc: Thomas Glexiner > Cc: Boqun Feng > Cc: Paul McKenney > Cc: Frederic Weisbecker > Cc: Randy Dunlap > Cc: Masami Hiramatsu > Cc: Fenguang Wu > Cc: Baohong Liu > Cc: Vedang Patel > Cc: kernel-team@android.com > Signed-off-by: Joel Fernandes > --- > include/linux/srcu.h | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/include/linux/srcu.h b/include/linux/srcu.h > index 2ec618979b20..a1c4947be877 100644 > --- a/include/linux/srcu.h > +++ b/include/linux/srcu.h > @@ -135,6 +135,11 @@ static inline int srcu_read_lock_held(const struct srcu_struct *sp) > */ > #define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0) > > +/** > + * srcu_dereference_notrace - no tracing and no lockdep calls from here > + */ > +#define srcu_dereference_notrace(p, sp) srcu_dereference_check((p), (sp), 1) Given that this is a one-liner, why not just use srcu_dereference_check() directly, with 1 as you do above to disable lockdep? Thanx, Paul > + > /** > * srcu_read_lock - register a new reader for an SRCU-protected structure. > * @sp: srcu_struct in which to register the new reader. > -- > 2.17.0.441.gb46fe60e1d-goog >