4 files changed, 7 insertions, 22 deletions

diff --git a/drivers/tty/ipwireless/tty.c b/drivers/tty/ipwireless/tty.c
index ebd5bff0f5c1..17ee3bf0926b 100644
--- a/drivers/tty/ipwireless/tty.c
+++ b/drivers/tty/ipwireless/tty.c
@@ -176,9 +176,6 @@ void ipwireless_tty_received(struct ipw_tty *tty, unsigned char *data,
                                 ": %d chars not inserted to flip buffer!\n",
                                 length - work);
 
-        /*
-         * This may sleep if ->low_latency is set
-         */
         if (work)
                 tty_flip_buffer_push(&tty->port);
 }
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 765125dff20e..8ebd9f88a6f6 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -351,14 +351,11 @@ EXPORT_SYMBOL(tty_insert_flip_string_flags);
  *      Takes any pending buffers and transfers their ownership to the
  *      ldisc side of the queue. It then schedules those characters for
  *      processing by the line discipline.
- *      Note that this function can only be used when the low_latency flag
- *      is unset. Otherwise the workqueue won't be flushed.
  */
 
 void tty_schedule_flip(struct tty_port *port)
 {
         struct tty_bufhead *buf = &port->buf;
-        WARN_ON(port->low_latency);
 
         buf->tail->commit = buf->tail->used;
         schedule_work(&buf->work);
@@ -482,17 +479,15 @@ static void flush_to_ldisc(struct work_struct *work)
  */
 void tty_flush_to_ldisc(struct tty_struct *tty)
 {
-        if (!tty->port->low_latency)
-                flush_work(&tty->port->buf.work);
+        flush_work(&tty->port->buf.work);
 }
 
 /**
  *      tty_flip_buffer_push    -       terminal
  *      @port: tty port to push
  *
- *      Queue a push of the terminal flip buffers to the line discipline. This
- *      function must not be called from IRQ context if port->low_latency is
- *      set.
+ *      Queue a push of the terminal flip buffers to the line discipline.
+ *      Can be called from IRQ/atomic context.
  *
  *      In the event of the queue being busy for flipping the work will be
  *      held off and retried later.
@@ -500,14 +495,7 @@ void tty_flush_to_ldisc(struct tty_struct *tty)
 
 void tty_flip_buffer_push(struct tty_port *port)
 {
-        struct tty_bufhead *buf = &port->buf;
-
-        buf->tail->commit = buf->tail->used;
-
-        if (port->low_latency)
-                flush_to_ldisc(&buf->work);
-        else
-                schedule_work(&buf->work);
+        tty_schedule_flip(port);
 }
 EXPORT_SYMBOL(tty_flip_buffer_push);
 
diff --git a/drivers/usb/gadget/u_serial.c b/drivers/usb/gadget/u_serial.c
index b369292d4b90..ad0aca812002 100644
--- a/drivers/usb/gadget/u_serial.c
+++ b/drivers/usb/gadget/u_serial.c
@@ -549,8 +549,8 @@ static void gs_rx_push(unsigned long _port)
                 port->read_started--;
         }
 
-        /* Push from tty to ldisc; without low_latency set this is handled by
-         * a workqueue, so we won't get callbacks and can hold port_lock
+        /* Push from tty to ldisc; this is handled by a workqueue,
+         * so we won't get callbacks and can hold port_lock
          */
         if (do_push)
                 tty_flip_buffer_push(&port->port);
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 90b4fdc8a61f..b90b5c221ff0 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -208,7 +208,7 @@ struct tty_port {
         wait_queue_head_t       delta_msr_wait; /* Modem status change */
         unsigned long           flags;          /* TTY flags ASY_*/
         unsigned char           console:1,      /* port is a console */
-                                low_latency:1;  /* direct buffer flush */
+                                low_latency:1;  /* optional: tune for latency */
         struct mutex            mutex;          /* Locking */
         struct mutex            buf_mutex;      /* Buffer alloc lock */
         unsigned char           *xmit_buf;      /* Optional buffer */