[PATCH 07/10] perf: Add group parameter to perf_event_read()

[Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>]

Add a 'group' parameter to perf_event_read(). It will be used (set
to true) in a follow-on patch to update event times of the group.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
---
 kernel/events/core.c |   17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 21a55d1..f38fe0b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3212,7 +3212,7 @@ static inline u64 perf_event_count(struct perf_event *event)
 	return __perf_event_count(event);
 }
 
-static int perf_event_read(struct perf_event *event)
+static int perf_event_read(struct perf_event *event, bool group)
 {
 	/*
 	 * If event is enabled and currently active on a CPU, update the
@@ -3235,7 +3235,12 @@ static int perf_event_read(struct perf_event *event)
 			update_context_time(ctx);
 			update_cgrp_time_from_event(event);
 		}
-		update_event_times(event);
+
+		if (group)
+			update_group_times(event);
+		else
+			update_event_times(event);
+
 		raw_spin_unlock_irqrestore(&ctx->lock, flags);
 	}
 
@@ -3722,7 +3727,7 @@ static u64 perf_event_aggregate(struct perf_event *event, u64 *enabled,
 	lockdep_assert_held(&event->child_mutex);
 
 	list_for_each_entry(child, &event->child_list, child_list) {
-		(void)perf_event_read(child);
+		(void)perf_event_read(child, false);
 		total += perf_event_count(child);
 		*enabled += child->total_time_enabled;
 		*running += child->total_time_running;
@@ -3776,7 +3781,7 @@ u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
 
 	mutex_lock(&event->child_mutex);
 
-	(void)perf_event_read(event);
+	(void)perf_event_read(event, false);
 	total = perf_event_aggregate(event, enabled, running);
 
 	mutex_unlock(&event->child_mutex);
@@ -3831,7 +3836,7 @@ static int perf_read_group(struct perf_event *event,
 
 		mutex_lock(&leader->child_mutex);
 
-		(void)perf_event_read(sub);
+		(void)perf_event_read(sub, false);
 		values[n++] = perf_event_aggregate(sub, &enabled, &running);
 
 		mutex_unlock(&leader->child_mutex);
@@ -3953,7 +3958,7 @@ static unsigned int perf_poll(struct file *file, poll_table *wait)
 
 static void _perf_event_reset(struct perf_event *event)
 {
-	(void)perf_event_read(event);
+	(void)perf_event_read(event, false);
 	local64_set(&event->count, 0);
 	perf_event_update_userpage(event);
 }
-- 
1.7.9.5