Merge tag 'v4.0.8' into xlnx_4.0.8-rt6

[zynq/linux.git] / drivers / tty / tty_buffer.c

diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 75661641f5fe068237e7830acd9472383964da3a..2f78b77f0f8180fa07df27ab2ab931cf73f53587 100644 (file)
--- 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;
@@ -488,19 +514,6 @@ static void flush_to_ldisc(struct work_struct *work)
        tty_ldisc_deref(disc);
 }
 
-/**
- *     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