From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754277AbeDWDGB (ORCPT ); Sun, 22 Apr 2018 23:06:01 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:57966 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753956AbeDWDCj (ORCPT ); Sun, 22 Apr 2018 23:02:39 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel.opensrc@gmail.com, torvalds@linux-foundation.org, npiggin@gmail.com, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 07/21] rcu: Make rcu_future_needs_gp() check all ->need_future_gps[] elements Date: Sun, 22 Apr 2018 20:03:30 -0700 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20180423030258.GA23370@linux.vnet.ibm.com> References: <20180423030258.GA23370@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18042303-0056-0000-0000-0000044377E0 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008903; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000257; SDB=6.01021898; UDB=6.00521542; IPR=6.00801133; MB=3.00020719; MTD=3.00000008; XFM=3.00000015; UTC=2018-04-23 03:02:36 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18042303-0057-0000-0000-000008878114 Message-Id: <1524452624-27589-7-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-04-23_01:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 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-1804230032 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, the rcu_future_needs_gp() function checks only the current element of the ->need_future_gps[] array, which might miss elements that were offset from the expected element, for example, due to races with the start or the end of a grace period. This commit therefore makes rcu_future_needs_gp() use the need_any_future_gp() macro to check all of the elements of this array. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 2 +- kernel/rcu/tree.h | 3 ++- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index afc5e32f0da4..b05ab6379562 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -720,7 +720,7 @@ static int rcu_future_needs_gp(struct rcu_state *rsp) struct rcu_node *rnp = rcu_get_root(rsp); lockdep_assert_irqs_disabled(); - return READ_ONCE(need_future_gp_element(rnp, rnp->completed)); + return need_any_future_gp(rnp); } /* diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 952cd0c223fe..123c30eac8b5 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -169,7 +169,8 @@ struct rcu_node { bool __nonzero = false; \ \ for (__i = 0; __i < ARRAY_SIZE((rnp)->need_future_gp); __i++) \ - __nonzero = __nonzero || (rnp)->need_future_gp[__i]; \ + __nonzero = __nonzero || \ + READ_ONCE((rnp)->need_future_gp[__i]); \ __nonzero; \ }) -- 2.5.2