Commit-ID: 537b85c870babacc1cf13235e92bee9de86210e0
Gitweb: http://git.kernel.org/tip/537b85c870babacc1cf13235e92bee9de86210e0
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Mon, 26 Jun 2017 17:59:02 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Tue, 25 Jul 2017 13:04:48 -0700
rcu: Eliminate rcu_state ->orphan_lock
The ->orphan_lock is acquired and released only within the
rcu_migrate_callbacks() function, which now acquires the root rcu_node
structure's ->lock. This commit therefore eliminates the ->orphan_lock
in favor of the root rcu_node structure's ->lock.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcu/tree.c | 15 +++------------
kernel/rcu/tree.h | 3 ---
2 files changed, 3 insertions(+), 15 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index c080c6e..58ab489 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -97,7 +97,6 @@ struct rcu_state sname##_state = { \
.gp_state = RCU_GP_IDLE, \
.gpnum = 0UL - 300UL, \
.completed = 0UL - 300UL, \
- .orphan_lock = __RAW_SPIN_LOCK_UNLOCKED(&sname##_state.orphan_lock), \
.orphan_pend = RCU_CBLIST_INITIALIZER(sname##_state.orphan_pend), \
.orphan_done = RCU_CBLIST_INITIALIZER(sname##_state.orphan_done), \
.barrier_mutex = __MUTEX_INITIALIZER(sname##_state.barrier_mutex), \
@@ -3853,15 +3852,12 @@ void rcu_report_dead(unsigned int cpu)
/*
* Send the specified CPU's RCU callbacks to the orphanage. The
- * specified CPU must be offline, and the caller must hold the
- * ->orphan_lock.
+ * specified CPU must be offline.
*/
static void
rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,
struct rcu_node *rnp, struct rcu_data *rdp)
{
- lockdep_assert_held(&rsp->orphan_lock);
-
/*
* Orphan the callbacks. First adjust the counts. This is safe
* because _rcu_barrier() excludes CPU-hotplug operations, so it
@@ -3891,14 +3887,12 @@ rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,
/*
* Adopt the RCU callbacks from the specified rcu_state structure's
- * orphanage. The caller must hold the ->orphan_lock.
+ * orphanage.
*/
static void rcu_adopt_orphan_cbs(struct rcu_state *rsp, unsigned long flags)
{
struct rcu_data *rdp = raw_cpu_ptr(rsp->rda);
- lockdep_assert_held(&rsp->orphan_lock);
-
/* Do the accounting first. */
if (rsp->orphan_done.len_lazy != rsp->orphan_done.len)
rcu_idle_count_callbacks_posted();
@@ -3939,12 +3933,9 @@ static void rcu_migrate_callbacks(int cpu, struct rcu_state *rsp)
}
raw_spin_lock_rcu_node(rnp_root); /* irqs already disabled. */
rcu_advance_cbs(rsp, rnp_root, rdp); /* Leverage recent GPs. */
- raw_spin_unlock_rcu_node(rnp_root);
-
- raw_spin_lock(&rsp->orphan_lock);
rcu_send_cbs_to_orphanage(cpu, rsp, rnp, rdp);
rcu_adopt_orphan_cbs(rsp, flags);
- raw_spin_unlock_irqrestore(&rsp->orphan_lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp_root, flags);
WARN_ONCE(rcu_segcblist_n_cbs(&rdp->cblist) != 0 ||
!rcu_segcblist_empty(&rdp->cblist),
"rcu_cleanup_dead_cpu: Callbacks on offline CPU %d: qlen=%lu, 1stCB=%p\n",
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 574513c..62b1d0b 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -348,14 +348,11 @@ struct rcu_state {
/* End of fields guarded by root rcu_node's lock. */
- raw_spinlock_t orphan_lock ____cacheline_internodealigned_in_smp;
- /* Protect following fields. */
struct rcu_cblist orphan_pend; /* Orphaned callbacks that */
/* need a grace period. */
struct rcu_cblist orphan_done; /* Orphaned callbacks that */
/* are ready to invoke. */
/* (Contains counts.) */
- /* End of fields guarded by orphan_lock. */
struct mutex barrier_mutex; /* Guards barrier fields. */
atomic_t barrier_cpu_count; /* # CPUs waiting on. */
--
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