tty: move global ldisc idle waitqueue to the individual ldisc

The global wait_queue that is used for line discipline idle handling is
moved to a separate wait_queue for each line instance. This prevents
unnecessary blocking on one line, because of idle handling on another
line.

Signed-off-by: Ivo Sieben <meltedpianoman@gmail.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/tty_ldisc.h b/include/linux/tty_ldisc.h
index ff7dc08..fb79dd8d 100644
--- a/include/linux/tty_ldisc.h
+++ b/include/linux/tty_ldisc.h
@@ -110,6 +110,7 @@
 #include <linux/fs.h>
 #include <linux/wait.h>
 #include <linux/pps_kernel.h>
+#include <linux/wait.h>
 
 struct tty_ldisc_ops {
 	int	magic;
@@ -154,6 +155,7 @@
 struct tty_ldisc {
 	struct tty_ldisc_ops *ops;
 	atomic_t users;
+	wait_queue_head_t wq_idle;
 };
 
 #define TTY_LDISC_MAGIC	0x5403