tty_kref_put(tty);
}
-/* Called under the sighand lock */
-
+/**
+ * proc_set_tty - set the controlling terminal
+ *
+ * Only callable by the session leader and only if it does not already have
+ * a controlling terminal.
+ *
+ * Caller must hold: tty_lock()
+ * a readlock on tasklist_lock
+ * sighand lock
+ */
static void __proc_set_tty(struct tty_struct *tty)
{
unsigned long flags;
- /* We should not have a session or pgrp to put here but.... */
spin_lock_irqsave(&tty->ctrl_lock, flags);
+ /*
+ * The session and fg pgrp references will be non-NULL if
+ * tiocsctty() is stealing the controlling tty
+ */
put_pid(tty->session);
put_pid(tty->pgrp);
tty->pgrp = get_pid(task_pgrp(current));
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(¤t->sighand->siglock);
if (!noctty &&
current->signal->leader &&
tty->session == NULL)
__proc_set_tty(tty);
spin_unlock_irq(¤t->sighand->siglock);
+ read_unlock(&tasklist_lock);
tty_unlock(tty);
- mutex_unlock(&tty_mutex);
return 0;
err_unlock:
mutex_unlock(&tty_mutex);
* 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
*/
static int tiocsctty(struct tty_struct *tty, int arg)
{
int ret = 0;
+
+ tty_lock(tty);
+ read_lock(&tasklist_lock);
+
if (current->signal->leader && (task_session(current) == tty->session))
- return ret;
+ goto unlock;
- mutex_lock(&tty_mutex);
/*
* The process must be a session leader and
* not have a controlling tty already.
/*
* Steal it away
*/
- read_lock(&tasklist_lock);
session_clear_tty(tty->session);
- read_unlock(&tasklist_lock);
} else {
ret = -EPERM;
goto unlock;
}
proc_set_tty(tty);
unlock:
- mutex_unlock(&tty_mutex);
+ read_unlock(&tasklist_lock);
+ tty_unlock(tty);
return ret;
}
}
EXPORT_SYMBOL_GPL(tty_get_pgrp);
+/*
+ * This checks not only the pgrp, but falls back on the pid if no
+ * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
+ * without this...
+ *
+ * The caller must hold rcu lock or the tasklist lock.
+ */
+static struct pid *session_of_pgrp(struct pid *pgrp)
+{
+ struct task_struct *p;
+ struct pid *sid = NULL;
+
+ p = pid_task(pgrp, PIDTYPE_PGID);
+ if (p == NULL)
+ p = pid_task(pgrp, PIDTYPE_PID);
+ if (p != NULL)
+ sid = task_session(p);
+
+ return sid;
+}
+
/**
* tiocgpgrp - get process group
* @tty: tty passed by user