tty: Redo current tty locking

[linux-2.6-omap-h63xx.git] / drivers / char / tty_io.c

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index b5f57d0b30ee1bdb5e931825010c59ab0b2627a2..f40298e9873a0f274a8563181efa394d0e04bf50 100644 (file)
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -739,13 +739,11 @@ void tty_vhangup_self(void)
 {
        struct tty_struct *tty;
 
-       mutex_lock(&tty_mutex);
        tty = get_current_tty();
        if (tty) {
                tty_vhangup(tty);
                tty_kref_put(tty);
        }
-       mutex_unlock(&tty_mutex);
 }
 
 /**
@@ -801,11 +799,9 @@ void disassociate_ctty(int on_exit)
        struct pid *tty_pgrp = NULL;
 
 
-       mutex_lock(&tty_mutex);
        tty = get_current_tty();
        if (tty) {
                tty_pgrp = get_pid(tty->pgrp);
-               mutex_unlock(&tty_mutex);
                lock_kernel();
                if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
                        tty_vhangup(tty);
@@ -822,7 +818,6 @@ void disassociate_ctty(int on_exit)
                        kill_pgrp(old_pgrp, SIGCONT, on_exit);
                        put_pid(old_pgrp);
                }
-               mutex_unlock(&tty_mutex);
                return;
        }
        if (tty_pgrp) {
@@ -837,7 +832,6 @@ void disassociate_ctty(int on_exit)
        current->signal->tty_old_pgrp = NULL;
        spin_unlock_irq(&current->sighand->siglock);
 
-       mutex_lock(&tty_mutex);
        tty = get_current_tty();
        if (tty) {
                unsigned long flags;
@@ -854,7 +848,6 @@ void disassociate_ctty(int on_exit)
                       " = NULL", tty);
 #endif
        }
-       mutex_unlock(&tty_mutex);
 
        /* Now clear signal->tty under the lock */
        read_lock(&tasklist_lock);
@@ -3180,14 +3173,11 @@ static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
 struct tty_struct *get_current_tty(void)
 {
        struct tty_struct *tty;
-       WARN_ON_ONCE(!mutex_is_locked(&tty_mutex));
+       unsigned long flags;
+
+       spin_lock_irqsave(&current->sighand->siglock, flags);
        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
-        * long as we hold tty_mutex.
-        */
-       barrier();
+       spin_unlock_irqrestore(&current->sighand->siglock, flags);
        return tty;
 }
 EXPORT_SYMBOL_GPL(get_current_tty);