From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
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" <paulmck@linux.vnet.ibm.com>
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 [thread overview]
Message-ID: <12548908983277-git-send-email-> (raw)
In-Reply-To: <20091007044748.GA12763@linux.vnet.ibm.com>
From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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 <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
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
next prev parent reply other threads:[~2009-10-07 4:49 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-07 4:47 [PATCH tip/core/rcu 0/3] rcu: prevent hangs by simplifying rcu_barrier/CPU-hotplug, fix lockdep complaint Paul E. McKenney
2009-10-07 4:48 ` [PATCH tip/core/rcu 1/3] rcu: move rcu_barrier() to rcutree Paul E. McKenney
2009-10-07 6:16 ` [tip:core/rcu] rcu: Move " tip-bot for Paul E. McKenney
2009-10-07 4:48 ` [PATCH tip/core/rcu 2/3] rcu: make hot-unplugged CPU relinquish its own RCU callbacks Paul E. McKenney
2009-10-07 6:17 ` [tip:core/rcu] rcu: Make " tip-bot for Paul E. McKenney
2009-10-07 13:16 ` [PATCH tip/core/rcu 2/3] rcu: make " Steven Rostedt
2009-10-07 13:50 ` Paul E. McKenney
2009-10-07 4:48 ` Paul E. McKenney [this message]
2009-10-07 6:17 ` [tip:core/rcu] rcu: Place root rcu_node structure in separate lockdep class tip-bot for Paul E. McKenney
2009-10-08 9:31 ` [PATCH tip/core/rcu 3/3] rcu: place " Peter Zijlstra
2009-10-07 6:14 ` [PATCH tip/core/rcu 0/3] rcu: prevent hangs by simplifying rcu_barrier/CPU-hotplug, fix lockdep complaint Ingo Molnar
2009-10-07 13:52 ` Paul E. McKenney
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