1 files changed, 4 insertions, 2 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index a0c1a29a507f..1ac2d1c5d84e 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1484,7 +1484,6 @@ asmlinkage long sys_setsid(void)
         pid_t session;
         int err = -EPERM;
 
-        mutex_lock(&tty_mutex);
         write_lock_irq(&tasklist_lock);
 
         /* Fail if I am already a session leader */
@@ -1504,12 +1503,15 @@ asmlinkage long sys_setsid(void)
 
         group_leader->signal->leader = 1;
         __set_special_pids(session, session);
+
+        spin_lock(&group_leader->sighand->siglock);
         group_leader->signal->tty = NULL;
         group_leader->signal->tty_old_pgrp = 0;
+        spin_unlock(&group_leader->sighand->siglock);
+
         err = process_group(group_leader);
 out:
         write_unlock_irq(&tasklist_lock);
-        mutex_unlock(&tty_mutex);
         return err;
 }