[PATCH v2] rcu: Fix some incorrect trace log in rcu_boost and rcuc kthreads

[Zqiang]

In rcu_boost kthreads, before invoke rcu_wait(), the trace string
should mark "Start boost kthread@rcu_wait", after rcu_wait() end,
mark "End boost kthread@rcu_wait". for boost kthread enter idle
state, the trace should also do same.
In rcuc kthreads, when the rcu_cpu_has_work is set zero, indicates
that there are no works to process, the rcuc kthreads will enter
waiting state, so the trace string should mark "Start @rcu_wait".

Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx>
---
 kernel/rcu/tree.c        | 2 +-
 kernel/rcu/tree_plugin.h | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 734c252c1e80..c1915408796f 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2465,7 +2465,7 @@ static void rcu_cpu_kthread(unsigned int cpu)
 			rcu_core();
 		local_bh_enable();
 		if (*workp == 0) {
-			trace_rcu_utilization(TPS("End CPU kthread@rcu_wait"));
+			trace_rcu_utilization(TPS("Start CPU kthread@rcu_wait"));
 			*statusp = RCU_KTHREAD_WAITING;
 			return;
 		}
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 7b0fe741a088..7b622b5196a8 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1114,10 +1114,10 @@ static int rcu_boost_kthread(void *arg)
 	trace_rcu_utilization(TPS("Start boost kthread@init"));
 	for (;;) {
 		WRITE_ONCE(rnp->boost_kthread_status, RCU_KTHREAD_WAITING);
-		trace_rcu_utilization(TPS("End boost kthread@rcu_wait"));
+		trace_rcu_utilization(TPS("Start boost kthread@rcu_wait"));
 		rcu_wait(READ_ONCE(rnp->boost_tasks) ||
 			 READ_ONCE(rnp->exp_tasks));
-		trace_rcu_utilization(TPS("Start boost kthread@rcu_wait"));
+		trace_rcu_utilization(TPS("End boost kthread@rcu_wait"));
 		WRITE_ONCE(rnp->boost_kthread_status, RCU_KTHREAD_RUNNING);
 		more2boost = rcu_boost(rnp);
 		if (more2boost)
@@ -1126,9 +1126,9 @@ static int rcu_boost_kthread(void *arg)
 			spincnt = 0;
 		if (spincnt > 10) {
 			WRITE_ONCE(rnp->boost_kthread_status, RCU_KTHREAD_YIELDING);
-			trace_rcu_utilization(TPS("End boost kthread@rcu_yield"));
-			schedule_timeout_idle(2);
 			trace_rcu_utilization(TPS("Start boost kthread@rcu_yield"));
+			schedule_timeout_idle(2);
+			trace_rcu_utilization(TPS("End boost kthread@rcu_yield"));
 			spincnt = 0;
 		}
 	}
-- 
2.25.1