Create a taskqueue for each wireless interface which provides a serialised

sleepable context for net80211 driver callbacks. This removes the need for USB
and firmware based drivers to roll their own code to defer the chip programming
for state changes, scan requests, channel changes and mcast/promisc updates.
When a driver callback completes the hardware state is now guaranteed to have
been updated and is in sync with net80211 layer.

This nukes around 1300 lines of code from the wireless device drivers making
them more readable and less race prone.

The net80211 layer has been updated as follows
 - all state/channel changes are serialised on the taskqueue.
 - ieee80211_new_state() always queues and can now be called from any context
 - scanning runs from a single taskq function and executes to completion. driver
   callbacks are synchronous so the channel, phy mode and rx filters are
   guaranteed to be set in hardware before probe request frames are
   transmitted.

Help and contributions from Sam Leffler.

Reviewed by:	sam

1 files changed, 20 insertions, 3 deletions

diff --git a/sys/net80211/ieee80211.c b/sys/net80211/ieee80211.c
index eb40f61..2e75965 100644
--- a/sys/net80211/ieee80211.c
+++ b/sys/net80211/ieee80211.c
@@ -33,7 +33,7 @@ __FBSDID("$FreeBSD$");
 #include "opt_wlan.h"
 
 #include <sys/param.h>
-#include <sys/systm.h> 
+#include <sys/systm.h>
 #include <sys/kernel.h>
 
 #include <sys/socket.h>
@@ -251,6 +251,12 @@ ieee80211_ifattach(struct ieee80211com *ic,
 
 	IEEE80211_LOCK_INIT(ic, ifp->if_xname);
 	TAILQ_INIT(&ic->ic_vaps);
+
+	/* Create a taskqueue for all state changes */
+	ic->ic_tq = taskqueue_create("ic_taskq", M_WAITOK | M_ZERO,
+	    taskqueue_thread_enqueue, &ic->ic_tq);
+	taskqueue_start_threads(&ic->ic_tq, 1, PI_NET, "%s taskq",
+	    ifp->if_xname);
 	/*
 	 * Fill in 802.11 available channel set, mark all
 	 * available channels as active, and pick a default
@@ -325,6 +331,7 @@ ieee80211_ifdetach(struct ieee80211com *ic)
 	ieee80211_node_detach(ic);
 	ifmedia_removeall(&ic->ic_media);
 
+	taskqueue_free(ic->ic_tq);
 	IEEE80211_LOCK_DESTROY(ic);
 	if_detach(ifp);
 }
@@ -554,7 +561,17 @@ ieee80211_vap_detach(struct ieee80211vap *vap)
 	 * while we cleanup internal state but that is hard.
 	 */
 	ieee80211_stop_locked(vap);
+	IEEE80211_UNLOCK(ic);
+
+	/*
+	 * Flush any deferred vap tasks.
+	 * NB: must be before ether_ifdetach() and removal from ic_vaps list
+	 */
+	ieee80211_draintask(ic, &vap->iv_nstate_task);
+	ieee80211_draintask(ic, &vap->iv_swbmiss_task);
 
+	IEEE80211_LOCK(ic);
+	KASSERT(vap->iv_state == IEEE80211_S_INIT , ("vap still running"));
 	TAILQ_REMOVE(&ic->ic_vaps, vap, iv_next);
 	ieee80211_syncflag_locked(ic, IEEE80211_F_WME);
 #ifdef IEEE80211_SUPPORT_SUPERG
@@ -627,9 +644,9 @@ ieee80211_syncifflag_locked(struct ieee80211com *ic, int flag)
 		/* XXX should we return 1/0 and let caller do this? */
 		if (ifp->if_drv_flags & IFF_DRV_RUNNING) {
 			if (flag == IFF_PROMISC)
-				ic->ic_update_promisc(ifp);
+				ieee80211_runtask(ic, &ic->ic_promisc_task);
 			else if (flag == IFF_ALLMULTI)
-				ic->ic_update_mcast(ifp);
+				ieee80211_runtask(ic, &ic->ic_mcast_task);
 		}
 	}
 }