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authorPaul E. McKenney <paul.mckenney@linaro.org>2012-09-20 16:59:47 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-10-23 14:46:47 -0700
commitabfd6e58aed4f89fd69b9b17bc4b4527efe3a645 (patch)
tree47c72852a260b3063ef362e4d68e6a8ce7f1f7c3
parent6f0c0580b70c89094b3422ba81118c7b959c7556 (diff)
rcu: Fix comment about _rcu_barrier()/orphanage exclusion
In the old days, _rcu_barrier() acquired ->onofflock to exclude rcu_send_cbs_to_orphanage(), which allowed the latter to avoid memory barriers in callback handling. However, _rcu_barrier() recently started doing get_online_cpus() to lock out CPU-hotplug operations entirely, which means that the comment in rcu_send_cbs_to_orphanage() that talks about ->onofflock is now obsolete. This commit therefore fixes the comment. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
-rw-r--r--kernel/rcutree.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 74df86bd9204..ac8aed8ee417 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1581,8 +1581,8 @@ rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,
{
/*
* Orphan the callbacks. First adjust the counts. This is safe
- * because ->onofflock excludes _rcu_barrier()'s adoption of
- * the callbacks, thus no memory barrier is required.
+ * because _rcu_barrier() excludes CPU-hotplug operations, so it
+ * cannot be running now. Thus no memory barrier is required.
*/
if (rdp->nxtlist != NULL) {
rsp->qlen_lazy += rdp->qlen_lazy;