undo CL 7310096 / 59da6744d66d

broke windows build

««« original CL description
runtime: ensure forward progress of runtime.Gosched() for locked goroutines
The removed code leads to the situation when M executes the same locked G again and again.
Fixes #4820.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7310096
»»»

TBR=dvyukov
CC=golang-dev
https://golang.org/cl/7343050

src/pkg/runtime/proc.c

@@ -397,6 +397,14 @@ canaddmcpu(void)
 static void
 gput(G *gp)
 {
+	M *mp;
+
+	// If g is wired, hand it off directly.
+	if((mp = gp->lockedm) != nil && canaddmcpu()) {
+		mnextg(mp, gp);
+		return;
+	}
+
 	// If g is the idle goroutine for an m, hand it off.
 	if(gp->idlem != nil) {
 		if(gp->idlem->idleg != nil) {

src/pkg/runtime/proc_test.go

@@ -46,36 +46,6 @@ func TestStopTheWorldDeadlock(t *testing.T) {
 	runtime.GOMAXPROCS(maxprocs)
 }
 
-func TestYieldProgress(t *testing.T) {
-	testYieldProgress(t, false)
-}
-
-func TestYieldLockedProgress(t *testing.T) {
-	testYieldProgress(t, true)
-}
-
-func testYieldProgress(t *testing.T, locked bool) {
-	c := make(chan bool)
-	cack := make(chan bool)
-	go func() {
-		if locked {
-			runtime.LockOSThread()
-		}
-		for {
-			select {
-			case <-c:
-				cack <- true
-				break
-			default:
-				runtime.Gosched()
-			}
-		}
-	}()
-	time.Sleep(10 * time.Millisecond)
-	c <- true
-	<-cack
-}
-
 func TestYieldLocked(t *testing.T) {
 	const N = 10
 	c := make(chan bool)