tty: Make get_current_tty use a kref

[safe/jmp/linux-2.6] / drivers / char / tty_io.c

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 9a76db3..4c0e4ed 100644 (file)
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -786,12 +786,12 @@ void disassociate_ctty(int on_exit)
        tty = get_current_tty();
        if (tty) {
                tty_pgrp = get_pid(tty->pgrp);
-               lock_kernel();
                mutex_unlock(&tty_mutex);
-               /* XXX: here we race, there is nothing protecting tty */
+               lock_kernel();
                if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
                        tty_vhangup(tty);
                unlock_kernel();
+               tty_kref_put(tty);
        } else if (on_exit) {
                struct pid *old_pgrp;
                spin_lock_irq(&current->sighand->siglock);
@@ -819,7 +819,6 @@ void disassociate_ctty(int on_exit)
        spin_unlock_irq(&current->sighand->siglock);
 
        mutex_lock(&tty_mutex);
-       /* It is possible that do_tty_hangup has free'd this tty */
        tty = get_current_tty();
        if (tty) {
                unsigned long flags;
@@ -829,6 +828,7 @@ void disassociate_ctty(int on_exit)
                tty->session = NULL;
                tty->pgrp = NULL;
                spin_unlock_irqrestore(&tty->ctrl_lock, flags);
+               tty_kref_put(tty);
        } else {
 #ifdef TTY_DEBUG_HANGUP
                printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
@@ -1806,6 +1806,8 @@ retry_open:
                index = tty->index;
                filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
                /* noctty = 1; */
+               /* FIXME: Should we take a driver reference ? */
+               tty_kref_put(tty);
                goto got_driver;
        }
 #ifdef CONFIG_VT
@@ -3135,7 +3137,7 @@ struct tty_struct *get_current_tty(void)
 {
        struct tty_struct *tty;
        WARN_ON_ONCE(!mutex_is_locked(&tty_mutex));
-       tty = current->signal->tty;
+       tty = tty_kref_get(current->signal->tty);
        /*
         * session->tty can be changed/cleared from under us, make sure we
         * issue the load. The obtained pointer, when not NULL, is valid as