From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936182AbeEYOSL (ORCPT ); Fri, 25 May 2018 10:18:11 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:58378 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935791AbeEYOSJ (ORCPT ); Fri, 25 May 2018 10:18:09 -0400 Date: Fri, 25 May 2018 07:19:42 -0700 From: "Paul E. McKenney" To: Anna-Maria Gleixner Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, bigeasy@linutronix.de, ebiederm@xmission.com Subject: Re: [PATCH v2 1/2] rcu: Update documentation of rcu_read_unlock() Reply-To: paulmck@linux.vnet.ibm.com References: <20180525090507.22248-1-anna-maria@linutronix.de> <20180525090507.22248-2-anna-maria@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180525090507.22248-2-anna-maria@linutronix.de> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18052514-0044-0000-0000-0000041B80CB X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009065; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000261; SDB=6.01036001; UDB=6.00529949; IPR=6.00815130; MB=3.00021234; MTD=3.00000008; XFM=3.00000015; UTC=2018-05-25 14:18:05 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18052514-0045-0000-0000-0000084D9F18 Message-Id: <20180525141942.GB3803@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-05-25_05:,, 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=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1805250154 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 25, 2018 at 11:05:06AM +0200, Anna-Maria Gleixner wrote: > Since commit b4abf91047cf ("rtmutex: Make wait_lock irq safe") the > explanation in rcu_read_unlock() documentation about irq unsafe rtmutex > wait_lock is no longer valid. > > Remove it to prevent kernel developers reading the documentation to rely on > it. > > Suggested-by: Eric W. Biederman > Signed-off-by: Anna-Maria Gleixner Reviewed-by: Paul E. McKenney Or let me know if you would like me to carry this patch. Either way, just let me know! Thanx, Paul > --- > include/linux/rcupdate.h | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h > index 36360d07f25b..64644fda3b22 100644 > --- a/include/linux/rcupdate.h > +++ b/include/linux/rcupdate.h > @@ -653,9 +653,7 @@ static inline void rcu_read_lock(void) > * Unfortunately, this function acquires the scheduler's runqueue and > * priority-inheritance spinlocks. This means that deadlock could result > * if the caller of rcu_read_unlock() already holds one of these locks or > - * any lock that is ever acquired while holding them; or any lock which > - * can be taken from interrupt context because rcu_boost()->rt_mutex_lock() > - * does not disable irqs while taking ->wait_lock. > + * any lock that is ever acquired while holding them. > * > * That said, RCU readers are never priority boosted unless they were > * preempted. Therefore, one way to avoid deadlock is to make sure > -- > 2.15.1 >