Refactor BlockWithTimer() to reduce duplicated code.

The users of Task.BlockWithTimer() are doing the same work.

PiperOrigin-RevId: 610358579

pkg/sentry/kernel/task_block.go

@@ -102,15 +102,23 @@ func (t *Task) BlockWithDeadline(C <-chan struct{}, haveDeadline bool, deadline
 	return err
 }
 
-// BlockWithTimer blocks t until an event is received from C or tchan, or t is
-// interrupted. It returns nil if an event is received from C, ETIMEDOUT if an
-// event is received from tchan, and linuxerr.ErrInterrupted if t is
-// interrupted.
+// BlockWithDeadlineFrom is similar to BlockWithDeadline, except it uses the
+// passed clock (instead of application monotonic clock).
 //
 // Most clients should use BlockWithDeadline or BlockWithTimeout instead.
 //
 // Preconditions: The caller must be running on the task goroutine.
-func (t *Task) BlockWithTimer(C <-chan struct{}, tchan <-chan struct{}) error {
+func (t *Task) BlockWithDeadlineFrom(C <-chan struct{}, clock ktime.Clock, haveDeadline bool, deadline ktime.Time) error {
+	if !haveDeadline {
+		return t.block(C, nil)
+	}
+	notifier, tchan := ktime.NewChannelNotifier()
+	timer := ktime.NewTimer(clock, notifier)
+	timer.Swap(ktime.Setting{
+		Enabled: true,
+		Next:    deadline,
+	})
+	defer timer.Destroy()
 	return t.block(C, tchan)
 }
 

pkg/sentry/syscalls/linux/sys_futex.go

@@ -61,14 +61,7 @@ func futexWaitAbsolute(t *kernel.Task, clockRealtime bool, ts linux.Timespec, fo
 	if forever {
 		err = t.Block(w.C)
 	} else if clockRealtime {
-		notifier, tchan := ktime.NewChannelNotifier()
-		timer := ktime.NewTimer(t.Kernel().RealtimeClock(), notifier)
-		timer.Swap(ktime.Setting{
-			Enabled: true,
-			Next:    ktime.FromTimespec(ts),
-		})
-		err = t.BlockWithTimer(w.C, tchan)
-		timer.Destroy()
+		err = t.BlockWithDeadlineFrom(w.C, t.Kernel().RealtimeClock(), true, ktime.FromTimespec(ts))
 	} else {
 		err = t.BlockWithDeadline(w.C, true, ktime.FromTimespec(ts))
 	}
@@ -138,14 +131,7 @@ func futexLockPI(t *kernel.Task, ts linux.Timespec, forever bool, addr hostarch.
 	if forever {
 		err = t.Block(w.C)
 	} else {
-		notifier, tchan := ktime.NewChannelNotifier()
-		timer := ktime.NewTimer(t.Kernel().RealtimeClock(), notifier)
-		timer.Swap(ktime.Setting{
-			Enabled: true,
-			Next:    ktime.FromTimespec(ts),
-		})
-		err = t.BlockWithTimer(w.C, tchan)
-		timer.Destroy()
+		err = t.BlockWithDeadlineFrom(w.C, t.Kernel().RealtimeClock(), true, ktime.FromTimespec(ts))
 	}
 
 	t.Futex().WaitComplete(w, t)

pkg/sentry/syscalls/linux/sys_time.go

@@ -245,15 +245,7 @@ func clockNanosleepUntil(t *kernel.Task, c ktime.Clock, end ktime.Time, rem host
 	if c == t.Kernel().MonotonicClock() {
 		err = t.BlockWithDeadline(nil, true, end)
 	} else {
-		notifier, tchan := ktime.NewChannelNotifier()
-		timer := ktime.NewTimer(c, notifier)
-		timer.Swap(ktime.Setting{
-			Period:  0,
-			Enabled: true,
-			Next:    end,
-		})
-		err = t.BlockWithTimer(nil, tchan)
-		timer.Destroy()
+		err = t.BlockWithDeadlineFrom(nil, c, true, end)
 	}
 
 	switch {