1 files changed, 27 insertions, 14 deletions

diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 75661641f5fe..2f78b77f0f81 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -37,6 +37,28 @@
 
 #define TTY_BUFFER_PAGE (((PAGE_SIZE - sizeof(struct tty_buffer)) / 2) & ~0xFF)
 
+/*
+ * If all tty flip buffers have been processed by flush_to_ldisc() or
+ * dropped by tty_buffer_flush(), check if the linked pty has been closed.
+ * If so, wake the reader/poll to process
+ */
+static inline void check_other_closed(struct tty_struct *tty)
+{
+        unsigned long flags, old;
+
+        /* transition from TTY_OTHER_CLOSED => TTY_OTHER_DONE must be atomic */
+        for (flags = ACCESS_ONCE(tty->flags);
+             test_bit(TTY_OTHER_CLOSED, &flags);
+             ) {
+                old = flags;
+                __set_bit(TTY_OTHER_DONE, &flags);
+                flags = cmpxchg(&tty->flags, old, flags);
+                if (old == flags) {
+                        wake_up_interruptible(&tty->read_wait);
+                        break;
+                }
+        }
+}
 
 /**
  *      tty_buffer_lock_exclusive       -       gain exclusive access to buffer
@@ -229,6 +251,8 @@ void tty_buffer_flush(struct tty_struct *tty, struct tty_ldisc *ld)
         if (ld && ld->ops->flush_buffer)
                 ld->ops->flush_buffer(tty);
 
+        check_other_closed(tty);
+
         atomic_dec(&buf->priority);
         mutex_unlock(&buf->lock);
 }
@@ -471,8 +495,10 @@ static void flush_to_ldisc(struct work_struct *work)
                 smp_rmb();
                 count = head->commit - head->read;
                 if (!count) {
-                        if (next == NULL)
+                        if (next == NULL) {
+                                check_other_closed(tty);
                                 break;
+                        }
                         buf->head = next;
                         tty_buffer_free(port, head);
                         continue;
@@ -489,19 +515,6 @@ static void flush_to_ldisc(struct work_struct *work)
 }
 
 /**
- *      tty_flush_to_ldisc
- *      @tty: tty to push
- *
- *      Push the terminal flip buffers to the line discipline.
- *
- *      Must not be called from IRQ context.
- */
-void tty_flush_to_ldisc(struct tty_struct *tty)
-{
-        flush_work(&tty->port->buf.work);
-}
-
-/**
  *      tty_flip_buffer_push    -       terminal
  *      @port: tty port to push
  *