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>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index fa65cde395a..173a9000a6c 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -28,7 +28,6 @@
 
 static DEFINE_SPINLOCK(tty_ldisc_lock);
 static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait);
-static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_idle);
 /* Line disc dispatch table */
 static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS];
 
@@ -65,7 +64,7 @@ static void put_ldisc(struct tty_ldisc *ld)
                 return;
         }
         local_irq_restore(flags);
-        wake_up(&tty_ldisc_idle);
+        wake_up(&ld->wq_idle);
 }
 
 /**
@@ -200,6 +199,8 @@ static struct tty_ldisc *tty_ldisc_get(int disc)
 
         ld->ops = ldops;
         atomic_set(&ld->users, 1);
+        init_waitqueue_head(&ld->wq_idle);
+
         return ld;
 }
 
@@ -538,7 +539,7 @@ static void tty_ldisc_flush_works(struct tty_struct *tty)
 static int tty_ldisc_wait_idle(struct tty_struct *tty, long timeout)
 {
         long ret;
-        ret = wait_event_timeout(tty_ldisc_idle,
+        ret = wait_event_timeout(tty->ldisc->wq_idle,
                         atomic_read(&tty->ldisc->users) == 1, timeout);
         return ret > 0 ? 0 : -EBUSY;
 }