__exit_signal: don't take rcu lock

There is no reason for rcu_read_lock() in __exit_signal().  tsk->sighand
can only be changed if tsk does exec, obviously this is not possible.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 2 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 93d2711b938..a7799d8a640 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -85,7 +85,6 @@ static void __exit_signal(struct task_struct *tsk)
         BUG_ON(!sig);
         BUG_ON(!atomic_read(&sig->count));
 
-        rcu_read_lock();
         sighand = rcu_dereference(tsk->sighand);
         spin_lock(&sighand->siglock);
 
@@ -136,7 +135,6 @@ static void __exit_signal(struct task_struct *tsk)
         tsk->signal = NULL;
         tsk->sighand = NULL;
         spin_unlock(&sighand->siglock);
-        rcu_read_unlock();
 
         __cleanup_sighand(sighand);
         clear_tsk_thread_flag(tsk,TIF_SIGPENDING);