From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751923AbeBZVw4 (ORCPT ); Mon, 26 Feb 2018 16:52:56 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:49704 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751553AbeBZVwu (ORCPT ); Mon, 26 Feb 2018 16:52:50 -0500 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, Lihao Liang , "Paul E. McKenney" Subject: [PATCH tip/core/rcu 01/20] rcu: Remove unnecessary spinlock in rcu_boot_init_percpu_data() Date: Mon, 26 Feb 2018 13:52:51 -0800 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20180226215219.GA27379@linux.vnet.ibm.com> References: <20180226215219.GA27379@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18022621-0036-0000-0000-000002C6D7FA X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008601; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000254; SDB=6.00995530; UDB=6.00506033; IPR=6.00774858; MB=3.00019751; MTD=3.00000008; XFM=3.00000015; UTC=2018-02-26 21:52:48 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18022621-0037-0000-0000-0000437841A0 Message-Id: <1519681990-31349-1-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-02-26_07:,, 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-1802260274 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lihao Liang Since rcu_boot_init_percpu_data() is only called at boot time, there is no data race and spinlock is not needed. Signed-off-by: Lihao Liang Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 491bdf39f276..66c73a214cff 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3636,12 +3636,9 @@ static void rcu_init_new_rnp(struct rcu_node *rnp_leaf) static void __init rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) { - unsigned long flags; struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); - struct rcu_node *rnp = rcu_get_root(rsp); /* Set up local state, ensuring consistent view of global state. */ - raw_spin_lock_irqsave_rcu_node(rnp, flags); rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu); rdp->dynticks = &per_cpu(rcu_dynticks, cpu); WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != 1); @@ -3649,7 +3646,6 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) rdp->cpu = cpu; rdp->rsp = rsp; rcu_boot_init_nocb_percpu_data(rdp); - raw_spin_unlock_irqrestore_rcu_node(rnp, flags); } /* -- 2.5.2