runtime: catch races between channel close and channel send in select

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/10137043

src/pkg/runtime/chan.c

@@ -186,7 +186,6 @@ runtime·chansend(ChanType *t, Hchan *c, byte *ep, bool *pres, void *pc)
 	}
 
 	runtime·lock(c);
-	// TODO(dvyukov): add similar instrumentation to select.
 	if(raceenabled)
 		runtime·racereadpc(c, pc, runtime·chansend);
 	if(c->closed)
@@ -946,6 +945,8 @@ loop:
 			break;
 
 		case CaseSend:
+			if(raceenabled)
+				runtime·racereadpc(c, cas->pc, runtime·chansend);
 			if(c->closed)
 				goto sclose;
 			if(c->dataqsiz > 0) {

src/pkg/runtime/race/testdata/chan_test.go

@@ -311,12 +311,35 @@ func TestRaceChanSendClose(t *testing.T) {
 	go func() {
 		defer func() {
 			recover()
+			compl <- true
 		}()
 		c <- 1
+	}()
+	go func() {
+		time.Sleep(10 * time.Millisecond)
+		close(c)
 		compl <- true
 	}()
+	<-compl
+	<-compl
+}
+
+func TestRaceChanSendSelectClose(t *testing.T) {
+	compl := make(chan bool, 2)
+	c := make(chan int, 1)
+	c1 := make(chan int)
+	go func() {
+		defer func() {
+			recover()
+			compl <- true
+		}()
+		time.Sleep(10 * time.Millisecond)
+		select {
+		case c <- 1:
+		case <-c1:
+		}
+	}()
 	go func() {
-		time.Sleep(1e7)
 		close(c)
 		compl <- true
 	}()