[PATCH 4.14 005/115] kernfs: fix barrier usage in __kernfs_new_node()

Greg Kroah-Hartman
2019-05-15T11:18:07Z

From: Andrea Parri <andrea.parri@amarulasolutions.com>

commit 998267900cee901c5d1dfa029a6304d00acbc29f upstream.

smp_mb__before_atomic() can not be applied to atomic_set(). Remove the
barrier and rely on RELEASE synchronization.

Fixes: ba16b2846a8c6 ("kernfs: add an API to get kernfs node from inode number")
Cc: stable@vger.kernel.org
Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/kernfs/dir.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -649,11 +649,10 @@ static struct kernfs_node *__kernfs_new_
kn->id.generation = gen;

/*
- * set ino first. This barrier is paired with atomic_inc_not_zero in
+ * set ino first. This RELEASE is paired with atomic_inc_not_zero in
* kernfs_find_and_get_node_by_ino
*/
- smp_mb__before_atomic();
- atomic_set(&kn->count, 1);
+ atomic_set_release(&kn->count, 1);
atomic_set(&kn->active, KN_DEACTIVATED_BIAS);
RB_CLEAR_NODE(&kn->rb);