Storing ipcs into IDRs

This patch converts casts of struct kern_ipc_perm to
   . struct msg_queue
   . struct sem_array
   . struct shmid_kernel
into the equivalent container_of() macro. It improves code maintenance
because the code need not change if kern_ipc_perm is no longer at the
beginning of the containing struct.

Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 4 deletions

diff --git a/ipc/msg.c b/ipc/msg.c
index 74e6720..9f54582 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -138,13 +138,17 @@ void __init msg_init(void)
 
 static inline struct msg_queue *msg_lock(struct ipc_namespace *ns, int id)
 {
-	return (struct msg_queue *) ipc_lock(&msg_ids(ns), id);
+	struct kern_ipc_perm *ipcp = ipc_lock(&msg_ids(ns), id);
+
+	return container_of(ipcp, struct msg_queue, q_perm);
 }
 
 static inline struct msg_queue *msg_lock_check(struct ipc_namespace *ns,
 						int id)
 {
-	return (struct msg_queue *) ipc_lock_check(&msg_ids(ns), id);
+	struct kern_ipc_perm *ipcp = ipc_lock_check(&msg_ids(ns), id);
+
+	return container_of(ipcp, struct msg_queue, q_perm);
 }
 
 static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
@@ -274,9 +278,11 @@ static void freeque(struct ipc_namespace *ns, struct msg_queue *msq)
 	ipc_rcu_putref(msq);
 }
 
-static inline int msg_security(void *msq, int msgflg)
+static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
 {
-	return security_msg_queue_associate((struct msg_queue *) msq, msgflg);
+	struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
+
+	return security_msg_queue_associate(msq, msgflg);
 }
 
 asmlinkage long sys_msgget(key_t key, int msgflg)