Merge branch 'tty-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6

* 'tty-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6:
  serial: mfd: adjust the baud rate setting
  TTY: open/hangup race fixup
  TTY: don't allow reopen when ldisc is changing
  NET: wan/x25, fix ldisc->open retval
  TTY: ldisc, fix open flag handling
  serial8250: Mark console as CON_ANYTIME

2 files changed, 13 insertions, 2 deletions

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index c05c5af5aa04..35480dd57a30 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -559,6 +559,9 @@ void __tty_hangup(struct tty_struct *tty)
 
         tty_lock();
 
+        /* some functions below drop BTM, so we need this bit */
+        set_bit(TTY_HUPPING, &tty->flags);
+
         /* inuse_filps is protected by the single tty lock,
            this really needs to change if we want to flush the
            workqueue with the lock held */
@@ -578,6 +581,10 @@ void __tty_hangup(struct tty_struct *tty)
         }
         spin_unlock(&tty_files_lock);
 
+        /*
+         * it drops BTM and thus races with reopen
+         * we protect the race by TTY_HUPPING
+         */
         tty_ldisc_hangup(tty);
 
         read_lock(&tasklist_lock);
@@ -615,7 +622,6 @@ void __tty_hangup(struct tty_struct *tty)
         tty->session = NULL;
         tty->pgrp = NULL;
         tty->ctrl_status = 0;
-        set_bit(TTY_HUPPED, &tty->flags);
         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 
         /* Account for the p->signal references we killed */
@@ -641,6 +647,7 @@ void __tty_hangup(struct tty_struct *tty)
          * can't yet guarantee all that.
          */
         set_bit(TTY_HUPPED, &tty->flags);
+        clear_bit(TTY_HUPPING, &tty->flags);
         tty_ldisc_enable(tty);
 
         tty_unlock();
@@ -1310,7 +1317,9 @@ static int tty_reopen(struct tty_struct *tty)
 {
         struct tty_driver *driver = tty->driver;
 
-        if (test_bit(TTY_CLOSING, &tty->flags))
+        if (test_bit(TTY_CLOSING, &tty->flags) ||
+                        test_bit(TTY_HUPPING, &tty->flags) ||
+                        test_bit(TTY_LDISC_CHANGING, &tty->flags))
                 return -EIO;
 
         if (driver->type == TTY_DRIVER_TYPE_PTY &&
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index d8e96b005023..4214d58276f7 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -454,6 +454,8 @@ static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld)
                 /* BTM here locks versus a hangup event */
                 WARN_ON(!tty_locked());
                 ret = ld->ops->open(tty);
+                if (ret)
+                        clear_bit(TTY_LDISC_OPEN, &tty->flags);
                 return ret;
         }
         return 0;