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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2009-10-06 21:48:18 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-10-07 08:11:21 +0200 |
| commit | 978c0b88146a7f9b364b71b5b83c5b12e7b413d7 (patch) | |
| tree | b68bedc40888192d329841a786f3b1214eab91ef /kernel | |
| parent | e74f4c4564455c91a3b4075bb1721993c2a95dda (diff) | |
| download | lwn-978c0b88146a7f9b364b71b5b83c5b12e7b413d7.tar.gz lwn-978c0b88146a7f9b364b71b5b83c5b12e7b413d7.zip | |
rcu: Place root rcu_node structure in separate lockdep class
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>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <12548908983277-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcutree.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index d8d98655c9e7..705f02ac7433 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); } /* |