[PATCH] unshare: Use rcu_assign_pointer when setting sighand

The sighand pointer only needs the rcu_read_lock on the
read side.  So only depending on task_lock protection
when setting this pointer is not enough.  We also need
a memory barrier to ensure the initialization is seen first.

Use rcu_assign_pointer as it does this for us, and clearly
documents that we are setting an rcu readable pointer.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index ccdfbb16c86d..46060cb24af0 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1569,7 +1569,7 @@ asmlinkage long sys_unshare(unsigned long unshare_flags)
 
                 if (new_sigh) {
                         sigh = current->sighand;
-                        current->sighand = new_sigh;
+                        rcu_assign_pointer(current->sighand, new_sigh);
                         new_sigh = sigh;
                 }