mac80211: generalise work handling

In order to use auth/assoc for different purposes
other than MLME, it needs to be split up. For other
purposes, a generic work handling (potentially on
another channel) will be useful.

To achieve that, this patch moves much of the MLME
work handling out of mlme into a new work API. The
API can currently handle probing a specific AP,
authentication and association. The MLME previously
handled probe/authentication as one step and will
continue to do so, but they are separate in the new
work handling.

Work items are RCU-managed to be able to check for
existence of an item for a specific frame in the RX
path, but they can be re-used which the MLME right
now will do for its combined probe/auth step.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index f60dfca..bfcf09e 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -1945,6 +1945,7 @@
 {
 	struct ieee80211_sub_if_data *sdata = rx->sdata;
 	struct ieee80211_mgmt *mgmt = (struct ieee80211_mgmt *) rx->skb->data;
+	ieee80211_rx_result rxs;
 
 	if (!(rx->flags & IEEE80211_RX_RA_MATCH))
 		return RX_DROP_MONITOR;
@@ -1952,6 +1953,10 @@
 	if (ieee80211_drop_unencrypted(rx, mgmt->frame_control))
 		return RX_DROP_MONITOR;
 
+	rxs = ieee80211_work_rx_mgmt(rx->sdata, rx->skb);
+	if (rxs != RX_CONTINUE)
+		return rxs;
+
 	if (ieee80211_vif_is_mesh(&sdata->vif))
 		return ieee80211_mesh_rx_mgmt(sdata, rx->skb);