From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754718AbZJGEtB (ORCPT ); Wed, 7 Oct 2009 00:49:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754373AbZJGEs7 (ORCPT ); Wed, 7 Oct 2009 00:48:59 -0400 Received: from e3.ny.us.ibm.com ([32.97.182.143]:41702 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753429AbZJGEs6 (ORCPT ); Wed, 7 Oct 2009 00:48:58 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, dvhltc@us.ibm.com, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 3/3] rcu: place root rcu_node structure in separate lockdep class Date: Tue, 6 Oct 2009 21:48:18 -0700 Message-Id: <12548908983277-git-send-email-> X-Mailer: git-send-email 1.5.2.5 In-Reply-To: <20091007044748.GA12763@linux.vnet.ibm.com> References: <20091007044748.GA12763@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Paul E. McKenney Before this patch, all of the rcu_node structures were in the same lockdep class, so that lockdep would complain when rcu_preempt_offline_tasks() acquired the root rcu_node structure's lock while holding one of the leaf rcu_nodes' locks. This patch changes rcu_init_one() to use a separate spin_lock_init() for the root rcu_node structure's lock than is used for that of all of the rest of the rcu_node structures, which puts the root rcu_node structure's lock in its own lockdep class. Suggested-by: Peter Zijlstra Signed-off-by: Paul E. McKenney --- kernel/rcutree.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index d8d9865..705f02a 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1647,7 +1647,8 @@ static void __init rcu_init_one(struct rcu_state *rsp) cpustride *= rsp->levelspread[i]; rnp = rsp->level[i]; for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { - spin_lock_init(&rnp->lock); + if (rnp != rcu_get_root(rsp)) + spin_lock_init(&rnp->lock); rnp->gpnum = 0; rnp->qsmask = 0; rnp->qsmaskinit = 0; @@ -1670,6 +1671,7 @@ static void __init rcu_init_one(struct rcu_state *rsp) INIT_LIST_HEAD(&rnp->blocked_tasks[1]); } } + spin_lock_init(&rcu_get_root(rsp)->lock); } /* -- 1.5.2.5