tty: Document locking for tty_port_block_til_ready()

[firefly-linux-kernel-4.4.55.git] / drivers / tty / tty_port.c

diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index f4698696abae4fca880829f11e12f71c09fdac52..69e072b5912759a4fe1f64c75cc7e3b4f48b89a9 100644 (file)
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -348,6 +348,11 @@ EXPORT_SYMBOL(tty_port_lower_dtr_rts);
  *     do carrier detect and the dtr_rts method if it supports software
  *     management of these lines. Note that the dtr/rts raise is done each
  *     iteration as a hangup may have previously dropped them while we wait.
+ *
+ *     Caller holds tty lock.
+ *
+ *      NB: May drop and reacquire tty lock when blocking, so tty and tty_port
+ *      may have changed state (eg., may have been hung up).
  */
 
 int tty_port_block_til_ready(struct tty_port *port,