nl80211: Reduce the number of nlctrl name resolution calls

The number of nlctrl name resolution calls required to connect to a
WPA2-PSK AP is 12. And each nlctrl name resolution call spends 55 micro
seconds on a lower spec CPU like Intel Atom N270. Reduce the number of
nctrl name resolution calls from 12 to 1 by caching the results of nctrl
name resolution calls on int size memory to speed up the connection
process a little bit.

Signed-off-by: Masashi Honma <masashi.honma@gmail.com>

src/drivers/driver_nl80211.c

@@ -604,7 +604,7 @@ static int nl_get_multicast_id(struct nl80211_global *global,
 	msg = nlmsg_alloc();
 	if (!msg)
 		return -ENOMEM;
-	if (!genlmsg_put(msg, 0, 0, genl_ctrl_resolve(global->nl, "nlctrl"),
+	if (!genlmsg_put(msg, 0, 0, global->nlctrl_id,
 			 0, 0, CTRL_CMD_GETFAMILY, 0) ||
 	    nla_put_string(msg, CTRL_ATTR_FAMILY_NAME, family)) {
 		nlmsg_free(msg);
@@ -1883,6 +1883,13 @@ static int wpa_driver_nl80211_init_nl_global(struct nl80211_global *global)
 		goto err;
 	}
 
+	global->nlctrl_id = genl_ctrl_resolve(global->nl, "nlctrl");
+	if (global->nlctrl_id < 0) {
+		wpa_printf(MSG_ERROR,
+			   "nl80211: 'nlctrl' generic netlink not found");
+		goto err;
+	}
+
 	global->nl_event = nl_create_handle(global->nl_cb, "event");
 	if (global->nl_event == NULL)
 		goto err;

src/drivers/driver_nl80211.h

@@ -32,6 +32,7 @@ struct nl80211_global {
 	struct nl_cb *nl_cb;
 	struct nl_sock *nl;
 	int nl80211_id;
+	int nlctrl_id;
 	int ioctl_sock; /* socket for ioctl() use */
 
 	struct nl_sock *nl_event;