Add POLLRDNORM/POLLWRNORM support.

On Linux these are meant to be equivalent to POLLIN/POLLOUT. Rather
than hack these on in sys_poll etc it felt cleaner to just cleanup
the call sites to notify for both events. This is what linux does
as well.

Fixes #5544

PiperOrigin-RevId: 364859977

pkg/sentry/fsimpl/devpts/line_discipline.go

@@ -141,7 +141,7 @@ func (l *lineDiscipline) setTermios(task *kernel.Task, args arch.SyscallArgument
 		l.inQueue.pushWaitBufLocked(l)
 		l.inQueue.readable = true
 		l.inQueue.mu.Unlock()
-		l.replicaWaiter.Notify(waiter.EventIn)
+		l.replicaWaiter.Notify(waiter.ReadableEvents)
 	}
 
 	return 0, err
@@ -185,9 +185,9 @@ func (l *lineDiscipline) inputQueueRead(ctx context.Context, dst usermem.IOSeque
 		return 0, err
 	}
 	if n > 0 {
-		l.masterWaiter.Notify(waiter.EventOut)
+		l.masterWaiter.Notify(waiter.WritableEvents)
 		if pushed {
-			l.replicaWaiter.Notify(waiter.EventIn)
+			l.replicaWaiter.Notify(waiter.ReadableEvents)
 		}
 		return n, nil
 	}
@@ -202,7 +202,7 @@ func (l *lineDiscipline) inputQueueWrite(ctx context.Context, src usermem.IOSequ
 		return 0, err
 	}
 	if n > 0 {
-		l.replicaWaiter.Notify(waiter.EventIn)
+		l.replicaWaiter.Notify(waiter.ReadableEvents)
 		return n, nil
 	}
 	return 0, syserror.ErrWouldBlock
@@ -220,9 +220,9 @@ func (l *lineDiscipline) outputQueueRead(ctx context.Context, dst usermem.IOSequ
 		return 0, err
 	}
 	if n > 0 {
-		l.replicaWaiter.Notify(waiter.EventOut)
+		l.replicaWaiter.Notify(waiter.WritableEvents)
 		if pushed {
-			l.masterWaiter.Notify(waiter.EventIn)
+			l.masterWaiter.Notify(waiter.ReadableEvents)
 		}
 		return n, nil
 	}
@@ -237,7 +237,7 @@ func (l *lineDiscipline) outputQueueWrite(ctx context.Context, src usermem.IOSeq
 		return 0, err
 	}
 	if n > 0 {
-		l.masterWaiter.Notify(waiter.EventIn)
+		l.masterWaiter.Notify(waiter.ReadableEvents)
 		return n, nil
 	}
 	return 0, syserror.ErrWouldBlock
@@ -397,7 +397,7 @@ func (*inputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte)
 		// Anything written to the readBuf will have to be echoed.
 		if l.termios.LEnabled(linux.ECHO) {
 			l.outQueue.writeBytes(cBytes, l)
-			l.masterWaiter.Notify(waiter.EventIn)
+			l.masterWaiter.Notify(waiter.ReadableEvents)
 		}
 
 		// If we finish a line, make it available for reading.

pkg/sentry/fsimpl/devpts/queue.go

@@ -69,7 +69,7 @@ func (q *queue) readReadiness(t *linux.KernelTermios) waiter.EventMask {
 	q.mu.Lock()
 	defer q.mu.Unlock()
 	if len(q.readBuf) > 0 && q.readable {
-		return waiter.EventIn
+		return waiter.ReadableEvents
 	}
 	return waiter.EventMask(0)
 }
@@ -79,7 +79,7 @@ func (q *queue) writeReadiness(t *linux.KernelTermios) waiter.EventMask {
 	q.mu.Lock()
 	defer q.mu.Unlock()
 	if q.waitBufLen < waitBufMaxBytes {
-		return waiter.EventOut
+		return waiter.WritableEvents
 	}
 	return waiter.EventMask(0)
 }