tty: Serialize proc_set_tty() with tty_lock

[linux-2.6-block.git] / drivers / tty / tty_io.c

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index ae8f53c7972d2cafbcc9832be7a98e6da9303712..07275d0e30a25d41a79c7a4bd702c5d234819616 100644 (file)
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -508,7 +508,8 @@ void proc_clear_tty(struct task_struct *p)
  * Only callable by the session leader and only if it does not already have
  * a controlling terminal.
  *
- * Caller must hold:  a readlock on tasklist_lock
+ * Caller must hold:  tty_lock()
+ *                   a readlock on tasklist_lock
  *                   sighand lock
  */
 static void __proc_set_tty(struct tty_struct *tty)
@@ -2152,11 +2153,8 @@ retry_open:
                goto retry_open;
        }
        clear_bit(TTY_HUPPED, &tty->flags);
-       tty_unlock(tty);
 
 
-       mutex_lock(&tty_mutex);
-       tty_lock(tty);
        read_lock(&tasklist_lock);
        spin_lock_irq(&current->sighand->siglock);
        if (!noctty &&
@@ -2167,7 +2165,6 @@ retry_open:
        spin_unlock_irq(&current->sighand->siglock);
        read_unlock(&tasklist_lock);
        tty_unlock(tty);
-       mutex_unlock(&tty_mutex);
        return 0;
 err_unlock:
        mutex_unlock(&tty_mutex);
@@ -2448,7 +2445,7 @@ static int fionbio(struct file *file, int __user *p)
  *     leader to set this tty as the controlling tty for the session.
  *
  *     Locking:
- *             Takes tty_mutex() to protect tty instance
+ *             Takes tty_lock() to serialize proc_set_tty() for this tty
  *             Takes tasklist_lock internally to walk sessions
  *             Takes ->siglock() when updating signal->tty
  */
@@ -2457,7 +2454,7 @@ static int tiocsctty(struct tty_struct *tty, int arg)
 {
        int ret = 0;
 
-       mutex_lock(&tty_mutex);
+       tty_lock(tty);
        read_lock(&tasklist_lock);
 
        if (current->signal->leader && (task_session(current) == tty->session))
@@ -2490,7 +2487,7 @@ static int tiocsctty(struct tty_struct *tty, int arg)
        proc_set_tty(tty);
 unlock:
        read_unlock(&tasklist_lock);
-       mutex_unlock(&tty_mutex);
+       tty_unlock(tty);
        return ret;
 }