diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 8ebd9f88a6f69ff85f63139944fad2542c789483..f1d30f6945af2cf8fece1a5a1b40d59aa46cd5e0 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -255,11 +255,16 @@ static int __tty_buffer_request_room(struct tty_port *port, size_t size,
 	if (change || left < size) {
 		/* This is the slow path - looking for new buffers to use */
 		if ((n = tty_buffer_alloc(port, size)) != NULL) {
+			unsigned long iflags;
+
 			n->flags = flags;
 			buf->tail = n;
+
+			spin_lock_irqsave(&buf->flush_lock, iflags);
 			b->commit = b->used;
-			smp_mb();
 			b->next = n;
+			spin_unlock_irqrestore(&buf->flush_lock, iflags);
+
 		} else if (change)
 			size = 0;
 		else
@@ -443,6 +448,7 @@ static void flush_to_ldisc(struct work_struct *work)
 	mutex_lock(&buf->lock);
 
 	while (1) {
+		unsigned long flags;
 		struct tty_buffer *head = buf->head;
 		int count;
 
@@ -450,14 +456,19 @@ static void flush_to_ldisc(struct work_struct *work)
 		if (atomic_read(&buf->priority))
 			break;
 
+		spin_lock_irqsave(&buf->flush_lock, flags);
 		count = head->commit - head->read;
 		if (!count) {
-			if (head->next == NULL)
+			if (head->next == NULL) {
+				spin_unlock_irqrestore(&buf->flush_lock, flags);
 				break;
+			}
 			buf->head = head->next;
+			spin_unlock_irqrestore(&buf->flush_lock, flags);
 			tty_buffer_free(port, head);
 			continue;
 		}
+		spin_unlock_irqrestore(&buf->flush_lock, flags);
 
 		count = receive_buf(tty, head, count);
 		if (!count)
@@ -512,6 +523,7 @@ void tty_buffer_init(struct tty_port *port)
 	struct tty_bufhead *buf = &port->buf;
 
 	mutex_init(&buf->lock);
+	spin_lock_init(&buf->flush_lock);
 	tty_buffer_reset(&buf->sentinel, 0);
 	buf->head = &buf->sentinel;
 	buf->tail = &buf->sentinel;
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 1c3316a47d7e0386d1ede163c4f795275efc8130..036cccd80d9ffa0c6c1a356fff4a53418643b7ae 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -61,6 +61,7 @@ struct tty_bufhead {
 	struct tty_buffer *head;	/* Queue head */
 	struct work_struct work;
 	struct mutex	   lock;
+	spinlock_t	   flush_lock;
 	atomic_t	   priority;
 	struct tty_buffer sentinel;
 	struct llist_head free;		/* Free queue head */