1 files changed, 4 insertions, 14 deletions

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index b5f57d0b30ee..f40298e9873a 100644
--- 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);