ipc/mqueue: remove unnecessary rb_init_node() calls

Commit d6629859b36d ("ipc/mqueue: improve performance of send/recv") and
ce2d52cc ("ipc/mqueue: add rbtree node caching support") introduced an
rbtree of message priorities, and usage of rb_init_node() to initialize
the corresponding nodes.  As it turns out, rb_init_node() is unnecessary
here, as the nodes are fully initialized on insertion by rb_link_node()
and the code doesn't access nodes that aren't inserted on the rbtree.

Removing the rb_init_node() calls as I removed that function during
rbtree API cleanups (the only other use of it was in a place that
similarly didn't require it).

Signed-off-by: Michel Lespinasse <walken@google.com>
Acked-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ipc/mqueue.c

@@ -142,7 +142,6 @@ static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
 		leaf = kmalloc(sizeof(*leaf), GFP_ATOMIC);
 		if (!leaf)
 			return -ENOMEM;
-		rb_init_node(&leaf->rb_node);
 		INIT_LIST_HEAD(&leaf->msg_list);
 		info->qsize += sizeof(*leaf);
 	}
@@ -1013,7 +1012,6 @@ SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 
 	if (!info->node_cache && new_leaf) {
 		/* Save our speculative allocation into the cache */
-		rb_init_node(&new_leaf->rb_node);
 		INIT_LIST_HEAD(&new_leaf->msg_list);
 		info->node_cache = new_leaf;
 		info->qsize += sizeof(*new_leaf);
@@ -1121,7 +1119,6 @@ SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
 
 	if (!info->node_cache && new_leaf) {
 		/* Save our speculative allocation into the cache */
-		rb_init_node(&new_leaf->rb_node);
 		INIT_LIST_HEAD(&new_leaf->msg_list);
 		info->node_cache = new_leaf;
 		info->qsize += sizeof(*new_leaf);