rcu: Move quiescent-state forcing into kthread

As the first step towards allowing quiescent-state forcing to be
preemptible, this commit moves RCU quiescent-state forcing into the
same kthread that is now used to initialize and clean up after grace
periods.  This is yet another step towards keeping scheduling
latency down to a dull roar.

Updated to change from raw_spin_lock_irqsave() to raw_spin_lock_irq()
and to remove the now-unused rcu_state structure fields as suggested by
Peter Zijlstra.

Reported-by: Mike Galbraith <mgalbraith@suse.de>
Reported-by: Dimitri Sivanich <sivanich@sgi.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 587963689328..eb8dcd1bc4b5 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -119,7 +119,7 @@ EXPORT_SYMBOL_GPL(rcu_batches_completed);
  */
 void rcu_force_quiescent_state(void)
 {
-        force_quiescent_state(&rcu_preempt_state, 0);
+        force_quiescent_state(&rcu_preempt_state);
 }
 EXPORT_SYMBOL_GPL(rcu_force_quiescent_state);
 
@@ -2076,16 +2076,16 @@ static void rcu_prepare_for_idle(int cpu)
 #ifdef CONFIG_TREE_PREEMPT_RCU
         if (per_cpu(rcu_preempt_data, cpu).nxtlist) {
                 rcu_preempt_qs(cpu);
-                force_quiescent_state(&rcu_preempt_state, 0);
+                force_quiescent_state(&rcu_preempt_state);
         }
 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
         if (per_cpu(rcu_sched_data, cpu).nxtlist) {
                 rcu_sched_qs(cpu);
-                force_quiescent_state(&rcu_sched_state, 0);
+                force_quiescent_state(&rcu_sched_state);
         }
         if (per_cpu(rcu_bh_data, cpu).nxtlist) {
                 rcu_bh_qs(cpu);
-                force_quiescent_state(&rcu_bh_state, 0);
+                force_quiescent_state(&rcu_bh_state);
         }
 
         /*