Do not copy sleep.Waker

sleep.Waker's fields are modified as values.

PiperOrigin-RevId: 320873451

3 files changed, 15 insertions, 13 deletions

diff --git a/pkg/sleep/BUILD b/pkg/sleep/BUILD
index e131455f7..ae0fe1522 100644
--- a/pkg/sleep/BUILD
+++ b/pkg/sleep/BUILD
@@ -12,6 +12,7 @@ go_library(
         "sleep_unsafe.go",
     ],
     visibility = ["//:sandbox"],
+    deps = ["//pkg/sync"],
 )
 
 go_test(
diff --git a/pkg/sleep/sleep_test.go b/pkg/sleep/sleep_test.go
index af47e2ba1..1dd11707d 100644
--- a/pkg/sleep/sleep_test.go
+++ b/pkg/sleep/sleep_test.go
@@ -379,10 +379,7 @@ func TestRace(t *testing.T) {
 // TestRaceInOrder tests that multiple wakers can continuously send wake requests to
 // the sleeper and that the wakers are retrieved in the order asserted.
 func TestRaceInOrder(t *testing.T) {
-	const wakers = 100
-	const wakeRequests = 10000
-
-	w := make([]Waker, wakers)
+	w := make([]Waker, 10000)
 	s := Sleeper{}
 
 	// Associate each waker and start goroutines that will assert them.
@@ -390,19 +387,16 @@ func TestRaceInOrder(t *testing.T) {
 		s.AddWaker(&w[i], i)
 	}
 	go func() {
-		n := 0
-		for n < wakeRequests {
-			wk := w[n%len(w)]
-			wk.Assert()
-			n++
+		for i := range w {
+			w[i].Assert()
 		}
 	}()
 
 	// Wait for all wake up notifications from all wakers.
-	for i := 0; i < wakeRequests; i++ {
-		v, _ := s.Fetch(true)
-		if got, want := v, i%wakers; got != want {
-			t.Fatalf("got  %d want %d", got, want)
+	for want := range w {
+		got, _ := s.Fetch(true)
+		if got != want {
+			t.Fatalf("got %d want %d", got, want)
 		}
 	}
 }
diff --git a/pkg/sleep/sleep_unsafe.go b/pkg/sleep/sleep_unsafe.go
index f68c12620..118805492 100644
--- a/pkg/sleep/sleep_unsafe.go
+++ b/pkg/sleep/sleep_unsafe.go
@@ -75,6 +75,8 @@ package sleep
 import (
 	"sync/atomic"
 	"unsafe"
+
+	"gvisor.dev/gvisor/pkg/sync"
 )
 
 const (
@@ -323,7 +325,12 @@ func (s *Sleeper) enqueueAssertedWaker(w *Waker) {
 //
 // This struct is thread-safe, that is, its methods can be called concurrently
 // by multiple goroutines.
+//
+// Note, it is not safe to copy a Waker as its fields are modified by value
+// (the pointer fields are individually modified with atomic operations).
 type Waker struct {
+	_ sync.NoCopy
+
 	// s is the sleeper that this waker can wake up. Only one sleeper at a
 	// time is allowed. This field can have three classes of values:
 	// nil -- the waker is not asserted: it either is not associated with