TTY: pty, fix pty counting

New version for commit: 24d406a6bf736f7aebdc8fa0f0ec86e0890c6d24

diff -uprN a/drivers/tty/pty.c b/drivers/tty/pty.c
@@ -36,13 +36,15 @@

static struct tty_driver *ptm_driver;
static struct tty_driver *pts_driver;
#endif
+static int pty_count;

static void pty_close(struct tty_struct *tty, struct file *filp)

{
    BUG_ON(!tty);
-    if (tty->driver->subtype == PTY_TYPE_MASTER)
+    if (tty->driver->subtype == PTY_TYPE_MASTER) {
        WARN_ON(tty->count > 1);
-    else {
+        pty_count--;
+    } else {
        if (tty->count > 2)
            return;
    }

@@ -446,7 +448,6 @@ static inline void legacy_pty_init(void) int pty_limit = NR_UNIX98_PTY_DEFAULT;
static int pty_limit_min;
static int pty_limit_max = NR_UNIX98_PTY_MAX; -static int pty_count;

static struct cdev ptmx_cdev;

@@ -599,15 +600,9 @@ free_mem_out:

    return -ENOMEM;
}

-static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty) -{
- pty_count--;
-}
-
static const struct tty_operations ptm_unix98_ops = {
.lookup = ptm_unix98_lookup,
.install = pty_unix98_install,
- .remove = pty_unix98_remove,
.open = pty_open,
.close = pty_close,
.write = pty_write,
@@ -624,7 +619,6 @@ static const struct tty_operations ptm_u
static const struct tty_operations pty_unix98_ops = {
.lookup = pts_unix98_lookup,
.install = pty_unix98_install,
- .remove = pty_unix98_remove,
.open = pty_open,
.close = pty_close,
.write = pty_write,