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/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index fa65cde..173a900 100644 (file)
--- 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;
 }

diff --git a/include/linux/tty_ldisc.h b/include/linux/tty_ldisc.h
index ff7dc08..fb79dd8 100644 (file)
--- 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_ops {
 struct tty_ldisc {
        struct tty_ldisc_ops *ops;
        atomic_t users;
+       wait_queue_head_t wq_idle;
 };
 
 #define TTY_LDISC_MAGIC        0x5403