1 files changed, 23 insertions, 7 deletions

diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 512c49f98e85..8e0924f55446 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -36,6 +36,7 @@
 
 #include <linux/kmod.h>
 #include <linux/nsproxy.h>
+#include <linux/ratelimit.h>
 
 /*
  *      This guards the refcounted line discipline lists. The lock
@@ -547,15 +548,16 @@ static void tty_ldisc_flush_works(struct tty_struct *tty)
 /**
  *      tty_ldisc_wait_idle     -       wait for the ldisc to become idle
  *      @tty: tty to wait for
+ *      @timeout: for how long to wait at most
  *
  *      Wait for the line discipline to become idle. The discipline must
  *      have been halted for this to guarantee it remains idle.
  */
-static int tty_ldisc_wait_idle(struct tty_struct *tty)
+static int tty_ldisc_wait_idle(struct tty_struct *tty, long timeout)
 {
-        int ret;
+        long ret;
         ret = wait_event_timeout(tty_ldisc_idle,
-                        atomic_read(&tty->ldisc->users) == 1, 5 * HZ);
+                        atomic_read(&tty->ldisc->users) == 1, timeout);
         if (ret < 0)
                 return ret;
         return ret > 0 ? 0 : -EBUSY;
@@ -665,7 +667,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
         tty_ldisc_flush_works(tty);
 
-        retval = tty_ldisc_wait_idle(tty);
+        retval = tty_ldisc_wait_idle(tty, 5 * HZ);
 
         tty_lock();
         mutex_lock(&tty->ldisc_mutex);
@@ -762,8 +764,6 @@ static int tty_ldisc_reinit(struct tty_struct *tty, int ldisc)
         if (IS_ERR(ld))
                 return -1;
 
-        WARN_ON_ONCE(tty_ldisc_wait_idle(tty));
-
         tty_ldisc_close(tty, tty->ldisc);
         tty_ldisc_put(tty->ldisc);
         tty->ldisc = NULL;
@@ -838,7 +838,7 @@ void tty_ldisc_hangup(struct tty_struct *tty)
         tty_unlock();
         cancel_work_sync(&tty->buf.work);
         mutex_unlock(&tty->ldisc_mutex);
-
+retry:
         tty_lock();
         mutex_lock(&tty->ldisc_mutex);
 
@@ -847,6 +847,22 @@ void tty_ldisc_hangup(struct tty_struct *tty)
            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();
+
+                        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 (reset == 0) {
 
                         if (!tty_ldisc_reinit(tty, tty->termios->c_line))