From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753036AbeEUEnH (ORCPT ); Mon, 21 May 2018 00:43:07 -0400 Received: from mail-pl0-f67.google.com ([209.85.160.67]:41928 "EHLO mail-pl0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752748AbeEUEmi (ORCPT ); Mon, 21 May 2018 00:42:38 -0400 X-Google-Smtp-Source: AB8JxZpUGAZlKhcB2vXsragHsHcx9yJ2nWC/mB5SpwaEbUDPbDJOsdmWYUpxD1vFu8EL5yYxtX1KyQ== From: Joel Fernandes X-Google-Original-From: Joel Fernandes To: linux-kernel@vger.kernel.org Cc: Joel Fernandes , "Paul E. McKenney" , Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , byungchul.park@lge.com, kernel-team@android.com Subject: [PATCH v3 4/4] rcu: Unlock non-start node only after accessing its gp_seq_needed Date: Sun, 20 May 2018 21:42:20 -0700 Message-Id: <20180521044220.123933-5-joel@joelfernandes.org> X-Mailer: git-send-email 2.17.0.441.gb46fe60e1d-goog In-Reply-To: <20180521044220.123933-1-joel@joelfernandes.org> References: <20180521044220.123933-1-joel@joelfernandes.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We acquire gp_seq_needed locklessly. To be safe, lets do the unlocking after the access. Signed-off-by: Joel Fernandes --- kernel/rcu/tree.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 879c67a31116..efbd21b2a1a6 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1603,13 +1603,13 @@ static bool rcu_start_this_gp(struct rcu_node *rnp_start, struct rcu_data *rdp, trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gp_seq), TPS("newreq")); ret = true; /* Caller must wake GP kthread. */ unlock_out: - if (rnp != rnp_start) - raw_spin_unlock_rcu_node(rnp); /* Push furthest requested GP to leaf node and rcu_data structure. */ if (ULONG_CMP_GE(rnp->gp_seq_needed, gp_seq_req)) { rnp_start->gp_seq_needed = gp_seq_req; rdp->gp_seq_needed = gp_seq_req; } + if (rnp != rnp_start) + raw_spin_unlock_rcu_node(rnp); return ret; } -- 2.17.0.441.gb46fe60e1d-goog