[PATCH tip/core/rcu 10/19] rcu: Add event tracing to dyntick_save_progress_counter().

[Paul E. McKenney]

From: Andreea-Cristina Bernat <bernat.ada@xxxxxxxxx>

This patch adds event tracing to dyntick_save_progress_counter() in the case
where it returns 1. I used the tracepoint string "dti" because this function
returns 1 in case the CPU is in dynticks idle mode.

Signed-off-by: Andreea-Cristina Bernat <bernat.ada@xxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
 kernel/rcu/tree.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index fca911b6b29c..c6fd0f15425c 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -772,7 +772,12 @@ static int dyntick_save_progress_counter(struct rcu_data *rdp,
 {
 	rdp->dynticks_snap = atomic_add_return(0, &rdp->dynticks->dynticks);
 	rcu_sysidle_check_cpu(rdp, isidle, maxj);
-	return (rdp->dynticks_snap & 0x1) == 0;
+	if ((rdp->dynticks_snap & 0x1) == 0) {
+		trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("dti"));
+		return 1;
+	} else {
+		return 0;
+	}
 }
 
 /*
-- 
1.8.1.5

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