[PATCH] KEYS: Reduce smp_mb() calls in key_put()

[Jarkko Sakkinen]

Rely only on the memory ordering of spin_unlock() when setting
KEY_FLAG_FINAL_PUT under key->user->lock in key_put().

Signed-off-by: Jarkko Sakkinen <jar...@kernel.org>
---
 security/keys/key.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/security/keys/key.c b/security/keys/key.c
index 7198cd2ac3a3..aecbd624612d 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -656,10 +656,12 @@ void key_put(struct key *key)
                                spin_lock_irqsave(&key->user->lock, flags);
                                key->user->qnkeys--;
                                key->user->qnbytes -= key->quotalen;
+                               set_bit(KEY_FLAG_FINAL_PUT, &key->flags);
                                spin_unlock_irqrestore(&key->user->lock, flags);
+                       } else {
+                               set_bit(KEY_FLAG_FINAL_PUT, &key->flags);
+                               smp_mb(); /* key->user before FINAL_PUT set. */
                        }
-                       smp_mb(); /* key->user before FINAL_PUT set. */
-                       set_bit(KEY_FLAG_FINAL_PUT, &key->flags);
                        schedule_work(&key_gc_work);
                }
        }
-- 
2.47.2