Minor memevent fixes.

- Call MemoryEvents.done.Add(1) outside of MemoryEvents.run() so that if
  MemoryEvents.Stop() => MemoryEvents.done.Wait() is called before the
  goroutine starts running, it still waits for the goroutine to stop.

- Use defer to call MemoryEvents.done.Done() in MemoryEvents.run() so that it's
  called even if the goroutine panics.

PiperOrigin-RevId: 228623307
Change-Id: I1b0459e7999606c1a1a271b16092b1ca87005015

1 files changed, 2 insertions, 2 deletions

diff --git a/pkg/sentry/kernel/memevent/memory_events.go b/pkg/sentry/kernel/memevent/memory_events.go
index 1a8e86827..b6283c5d1 100644
--- a/pkg/sentry/kernel/memevent/memory_events.go
+++ b/pkg/sentry/kernel/memevent/memory_events.go
@@ -69,11 +69,12 @@ func (m *MemoryEvents) Start() {
 	if m.period == 0 {
 		return
 	}
+	m.done.Add(1)
 	go m.run() // S/R-SAFE: doesn't interact with saved state.
 }
 
 func (m *MemoryEvents) run() {
-	m.done.Add(1)
+	defer m.done.Done()
 
 	// Emit the first event immediately on startup.
 	totalTicks.Increment()
@@ -85,7 +86,6 @@ func (m *MemoryEvents) run() {
 	for {
 		select {
 		case <-m.stop:
-			m.done.Done()
 			return
 		case <-ticker.C:
 			totalTicks.Increment()