tty: Refactor wait for ldisc refs out of tty_ldisc_hangup()

Refactor tty_ldisc_hangup() to extract standalone function,
tty_ldisc_hangup_wait_idle(), to wait for ldisc references
to be released.

Signed-off-by: Peter Hurley <peter@hurleysoftware.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 c641321..c5b848a 100644 (file)
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -550,6 +550,41 @@ static int tty_ldisc_wait_idle(struct tty_struct *tty, long timeout)
        return ret > 0 ? 0 : -EBUSY;
 }
 
+/**
+ *     tty_ldisc_hangup_wait_idle - wait for the ldisc to become idle
+ *     @tty: tty to wait for
+ *
+ *     Wait for the line discipline to become idle. The discipline must
+ *     have been halted for this to guarantee it remains idle.
+ *
+ *     Caller must hold legacy and ->ldisc_mutex.
+ */
+static bool tty_ldisc_hangup_wait_idle(struct tty_struct *tty)
+{
+       while (tty->ldisc) {    /* Not yet closed */
+               if (atomic_read(&tty->ldisc->users) != 1) {
+                       char cur_n[TASK_COMM_LEN], tty_n[64];
+                       long timeout = 3 * HZ;
+                       tty_unlock(tty);
+
+                       while (tty_ldisc_wait_idle(tty, timeout) == -EBUSY) {
+                               timeout = MAX_SCHEDULE_TIMEOUT;
+                               printk_ratelimited(KERN_WARNING
+                                       "%s: waiting (%s) for %s took too long, but we keep waiting...\n",
+                                       __func__, get_task_comm(cur_n, current),
+                                       tty_name(tty, tty_n));
+                       }
+                       /* must reacquire both locks and preserve lock order */
+                       mutex_unlock(&tty->ldisc_mutex);
+                       tty_lock(tty);
+                       mutex_lock(&tty->ldisc_mutex);
+                       continue;
+               }
+               break;
+       }
+       return !!tty->ldisc;
+}
+
 /**
  *     tty_set_ldisc           -       set line discipline
  *     @tty: the terminal to set
@@ -826,7 +861,6 @@ void tty_ldisc_hangup(struct tty_struct *tty)
        cancel_work_sync(&tty->port->buf.work);
        set_bit(TTY_LDISC_HALTED, &tty->flags);
        mutex_unlock(&tty->ldisc_mutex);
-retry:
        tty_lock(tty);
        mutex_lock(&tty->ldisc_mutex);
 
@@ -834,23 +868,7 @@ retry:
           reopen it. We could defer this to the next open but
           it means auditing a lot of other paths so this is
           a FIXME */
-       if (tty->ldisc) {       /* Not yet closed */
-               if (atomic_read(&tty->ldisc->users) != 1) {
-                       char cur_n[TASK_COMM_LEN], tty_n[64];
-                       long timeout = 3 * HZ;
-                       tty_unlock(tty);
-
-                       while (tty_ldisc_wait_idle(tty, timeout) == -EBUSY) {
-                               timeout = MAX_SCHEDULE_TIMEOUT;
-                               printk_ratelimited(KERN_WARNING
-                                       "%s: waiting (%s) for %s took too long, but we keep waiting...\n",
-                                       __func__, get_task_comm(cur_n, current),
-                                       tty_name(tty, tty_n));
-                       }
-                       mutex_unlock(&tty->ldisc_mutex);
-                       goto retry;
-               }
-
+       if (tty_ldisc_hangup_wait_idle(tty)) {
                if (reset == 0) {
 
                        if (!tty_ldisc_reinit(tty, tty->termios.c_line))