9p-trans_fd: fix and clean up module init/exit paths

trans_fd leaked p9_mux_wq on module unload.  Fix it.  While at it,
collapse p9_mux_global_init() into p9_trans_fd_init().  It's easier to
follow this way and the global poll_tasks array is about to removed
anyway.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NEric Van Hensbergen <ericvh@gmail.com>

net/9p/trans_fd.c

@@ -238,22 +238,6 @@ static int p9_conn_rpcnb(struct p9_conn *m, struct p9_fcall *tc,
 
 static void p9_conn_cancel(struct p9_conn *m, int err);
 
-static int p9_mux_global_init(void)
-{
-	int i;
-
-	for (i = 0; i < ARRAY_SIZE(p9_mux_poll_tasks); i++)
-		p9_mux_poll_tasks[i].task = NULL;
-
-	p9_mux_wq = create_workqueue("v9fs");
-	if (!p9_mux_wq) {
-		printk(KERN_WARNING "v9fs: mux: creating workqueue failed\n");
-		return -ENOMEM;
-	}
-
-	return 0;
-}
-
 static u16 p9_mux_get_tag(struct p9_conn *m)
 {
 	int tag;
@@ -1616,10 +1600,15 @@ static struct p9_trans_module p9_fd_trans = {
 
 int p9_trans_fd_init(void)
 {
-	int ret = p9_mux_global_init();
-	if (ret) {
-		printk(KERN_WARNING "9p: starting mux failed\n");
-		return ret;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(p9_mux_poll_tasks); i++)
+		p9_mux_poll_tasks[i].task = NULL;
+
+	p9_mux_wq = create_workqueue("v9fs");
+	if (!p9_mux_wq) {
+		printk(KERN_WARNING "v9fs: mux: creating workqueue failed\n");
+		return -ENOMEM;
 	}
 
 	v9fs_register_trans(&p9_tcp_trans);
@@ -1634,4 +1623,6 @@ void p9_trans_fd_exit(void)
 	v9fs_unregister_trans(&p9_tcp_trans);
 	v9fs_unregister_trans(&p9_unix_trans);
 	v9fs_unregister_trans(&p9_fd_trans);
+
+	destroy_workqueue(p9_mux_wq);
 }