[PATCH 06/10] perf: Add return value for perf_event_read().

[Sukadev Bhattiprolu]

Add a return value to perf_event_read(). The return value will be
needed later in perf_read_group() implements ability to read several
counters in a PERF_PMU_TXN_READ transaction.

Signed-off-by: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com>
---
 kernel/events/core.c |   19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 0ce3012..21a55d1 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 void perf_event_read(struct perf_event *event)
+static int perf_event_read(struct perf_event *event)
 {
        /*
         * If event is enabled and currently active on a CPU, update the
@@ -3238,6 +3238,8 @@ static void perf_event_read(struct perf_event *event)
                update_event_times(event);
                raw_spin_unlock_irqrestore(&ctx->lock, flags);
        }
+
+       return 0;
 }
 
 /*
@@ -3720,7 +3722,7 @@ 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) {
-               perf_event_read(child);
+               (void)perf_event_read(child);
                total += perf_event_count(child);
                *enabled += child->total_time_enabled;
                *running += child->total_time_running;
@@ -3774,7 +3776,7 @@ u64 perf_event_read_value(struct perf_event *event, u64 
*enabled, u64 *running)
 
        mutex_lock(&event->child_mutex);
 
-       perf_event_read(event);
+       (void)perf_event_read(event);
        total = perf_event_aggregate(event, enabled, running);
 
        mutex_unlock(&event->child_mutex);
@@ -3798,7 +3800,12 @@ static int perf_read_group(struct perf_event *event,
 
        mutex_lock(&leader->child_mutex);
 
-       perf_event_read(leader);
+       ret = perf_event_read(leader);
+       if (ret) {
+               mutex_unlock(&leader->child_mutex);
+               return ret;
+       }
+
        count = perf_event_aggregate(leader, &enabled, &running);
 
        mutex_unlock(&leader->child_mutex);
@@ -3824,7 +3831,7 @@ static int perf_read_group(struct perf_event *event,
 
                mutex_lock(&leader->child_mutex);
 
-               perf_event_read(sub);
+               (void)perf_event_read(sub);
                values[n++] = perf_event_aggregate(sub, &enabled, &running);
 
                mutex_unlock(&leader->child_mutex);
@@ -3946,7 +3953,7 @@ static unsigned int perf_poll(struct file *file, 
poll_table *wait)
 
 static void _perf_event_reset(struct perf_event *event)
 {
-       perf_event_read(event);
+       (void)perf_event_read(event);
        local64_set(&event->count, 0);
        perf_event_update_userpage(event);
 }
-- 
1.7.9.5

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