1 files changed, 12 insertions, 6 deletions

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index f40298e9873a..2e96ce0fddc5 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1227,7 +1227,8 @@ static void tty_line_name(struct tty_driver *driver, int index, char *p)
  *      init_dev                -       initialise a tty device
  *      @driver: tty driver we are opening a device on
  *      @idx: device index
- *      @tty: returned tty structure
+ *      @ret_tty: returned tty structure
+ *      @first_ok: ok to open a new device (used by ptmx)
  *
  *      Prepare a tty device. This may not be a "new" clean device but
  *      could also be an active device. The pty drivers require special
@@ -1248,7 +1249,7 @@ static void tty_line_name(struct tty_driver *driver, int index, char *p)
  */
 
 static int init_dev(struct tty_driver *driver, int idx,
-        struct tty_struct **ret_tty)
+        struct tty_struct **ret_tty, int first_ok)
 {
         struct tty_struct *tty, *o_tty;
         struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc;
@@ -1279,6 +1280,11 @@ static int init_dev(struct tty_driver *driver, int idx,
         }
         if (tty) goto fast_track;
 
+        if (driver->subtype == PTY_TYPE_MASTER &&
+                (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
+                retval = -EIO;
+                goto end_init;
+        }
         /*
          * First time open is complex, especially for PTY devices.
          * This code guarantees that either everything succeeds and the
@@ -1413,7 +1419,7 @@ static int init_dev(struct tty_driver *driver, int idx,
 
         if (retval)
                 goto release_mem_out;
-         goto success;
+        goto success;
 
         /*
          * This fast open can be used if the tty is already open.
@@ -1795,7 +1801,7 @@ static void release_dev(struct file *filp)
 }
 
 /**
- *      tty_open                -       open a tty device
+ *      __tty_open              -       open a tty device
  *      @inode: inode of device file
  *      @filp: file pointer to tty
  *
@@ -1874,7 +1880,7 @@ retry_open:
                 return -ENODEV;
         }
 got_driver:
-        retval = init_dev(driver, index, &tty);
+        retval = init_dev(driver, index, &tty, 0);
         mutex_unlock(&tty_mutex);
         if (retval)
                 return retval;
@@ -1971,7 +1977,7 @@ static int __ptmx_open(struct inode *inode, struct file *filp)
                 return index;
 
         mutex_lock(&tty_mutex);
-        retval = init_dev(ptm_driver, index, &tty);
+        retval = init_dev(ptm_driver, index, &tty, 1);
         mutex_unlock(&tty_mutex);
 
         if (retval)