KEYS: Add an RCU payload dereference macro

Add an RCU payload dereference macro as this seems to be a common piece of code
amongst key types that use RCU referenced payloads.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/key.h b/include/linux/key.h
index 3db0adce1fda..a6b1edcffc34 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -275,6 +275,10 @@ static inline key_serial_t key_serial(struct key *key)
         return key ? key->serial : 0;
 }
 
+#define rcu_dereference_key(KEY)                                        \
+        (rcu_dereference_protected((KEY)->payload.rcudata,              \
+                                   rwsem_is_locked(&((struct key *)(KEY))->sem)))
+
 #ifdef CONFIG_SYSCTL
 extern ctl_table key_sysctls[];
 #endif