runtime: model wakeableSleep.lock in the race detector

Currently the flight recorder tests are failing in race mode because the
race detector doesn't see s.lock, leading to false positives. This has
also appeared in the trace tests. Model the lock in the race detector.

Fixes #65207.
Fixes #65283.

Change-Id: I1e9a5c9606536f55fdfc46b5f8443e9c7213c23d
Reviewed-on: https://go-review.googlesource.com/c/go/+/560215
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Pratt <mpratt@google.com>

src/runtime/trace2.go

@@ -932,7 +932,13 @@ func newWakeableSleep() *wakeableSleep {
 func (s *wakeableSleep) sleep(ns int64) {
 	resetTimer(s.timer, nanotime()+ns)
 	lock(&s.lock)
+	if raceenabled {
+		raceacquire(unsafe.Pointer(&s.lock))
+	}
 	wakeup := s.wakeup
+	if raceenabled {
+		racerelease(unsafe.Pointer(&s.lock))
+	}
 	unlock(&s.lock)
 	<-wakeup
 	stopTimer(s.timer)
@@ -945,6 +951,9 @@ func (s *wakeableSleep) wake() {
 	// Grab the wakeup channel, which may be nil if we're
 	// racing with close.
 	lock(&s.lock)
+	if raceenabled {
+		raceacquire(unsafe.Pointer(&s.lock))
+	}
 	if s.wakeup != nil {
 		// Non-blocking send.
 		//
@@ -956,6 +965,9 @@ func (s *wakeableSleep) wake() {
 		default:
 		}
 	}
+	if raceenabled {
+		racerelease(unsafe.Pointer(&s.lock))
+	}
 	unlock(&s.lock)
 }
 
@@ -969,11 +981,18 @@ func (s *wakeableSleep) wake() {
 func (s *wakeableSleep) close() {
 	// Set wakeup to nil so that a late timer ends up being a no-op.
 	lock(&s.lock)
+	if raceenabled {
+		raceacquire(unsafe.Pointer(&s.lock))
+	}
 	wakeup := s.wakeup
 	s.wakeup = nil
 
 	// Close the channel.
 	close(wakeup)
+
+	if raceenabled {
+		racerelease(unsafe.Pointer(&s.lock))
+	}
 	unlock(&s.lock)
 	return
 }