Simplify atomic operations

PiperOrigin-RevId: 294582802

pkg/sleep/commit_noasm.go

@@ -28,15 +28,6 @@ import "sync/atomic"
 // It is written in assembly because it is called from g0, so it doesn't have
 // a race context.
 func commitSleep(g uintptr, waitingG *uintptr) bool {
-	for {
-		// Check if the wait was aborted.
-		if atomic.LoadUintptr(waitingG) == 0 {
-			return false
-		}
-
-		// Try to store the G so that wakers know who to wake.
-		if atomic.CompareAndSwapUintptr(waitingG, preparingG, g) {
-			return true
-		}
-	}
+	// Try to store the G so that wakers know who to wake.
+	return atomic.CompareAndSwapUintptr(waitingG, preparingG, g)
 }

pkg/sleep/sleep_unsafe.go

@@ -299,20 +299,17 @@ func (s *Sleeper) enqueueAssertedWaker(w *Waker) {
 		}
 	}
 
-	for {
-		// Nothing to do if there isn't a G waiting.
-		g := atomic.LoadUintptr(&s.waitingG)
-		if g == 0 {
-			return
-		}
+	// Nothing to do if there isn't a G waiting.
+	if atomic.LoadUintptr(&s.waitingG) == 0 {
+		return
+	}
 
-		// Signal to the sleeper that a waker has been asserted.
-		if atomic.CompareAndSwapUintptr(&s.waitingG, g, 0) {
-			if g != preparingG {
-				// We managed to get a G. Wake it up.
-				goready(g, 0)
-			}
-		}
+	// Signal to the sleeper that a waker has been asserted.
+	switch g := atomic.SwapUintptr(&s.waitingG, 0); g {
+	case 0, preparingG:
+	default:
+		// We managed to get a G. Wake it up.
+		goready(g, 0)
 	}
 }