replace IFF_OACTIVE manipulation with mpsafe operations.

there are two things shared between the network stack and drivers
in the send path: the send queue and the IFF_OACTIVE flag. the send
queue is now protected by a mutex. this diff makes the oactive
functionality mpsafe too.

IFF_OACTIVE is part of if_flags. there are two problems with that.
firstly, if_flags is a short and we dont have any MI atomic operations
to manipulate a short. secondly, while we could make the IFF_OACTIVE
operates mpsafe, all changes to other flags would have to be made
safe at the same time, otherwise a read-modify-write cycle on their
updates could clobber the oactive change.

instead, this moves the oactive mark into struct ifqueue and provides
an API for changing it. there's ifq_set_oactive, ifq_clr_oactive,
and ifq_is_oactive. these are modelled on ifsq_set_oactive,
ifsq_clr_oactive, and ifsq_is_oactive in dragonflybsd.

this diff includes changes to all the drivers manipulating IFF_OACTIVE
to now use the ifsq_{set,clr_is}_oactive API too.

ok kettenis@ mpi@ jmatthew@ deraadt@

1 files changed, 8 insertions, 7 deletions

diff --git a/sys/dev/ic/rt2661.c b/sys/dev/ic/rt2661.c
index e58b6eb31c3..15656768762 100644
--- a/sys/dev/ic/rt2661.c
+++ b/sys/dev/ic/rt2661.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rt2661.c,v 1.87 2015/11/24 13:33:17 mpi Exp $	*/
+/*	$OpenBSD: rt2661.c,v 1.88 2015/11/25 03:09:58 dlg Exp $	*/
 
 /*-
  * Copyright (c) 2006
@@ -1150,7 +1150,7 @@ rt2661_tx_dma_intr(struct rt2661_softc *sc, struct rt2661_tx_ring *txq)
 		if (sc->txq[0].queued < RT2661_TX_RING_COUNT - 1)
 			sc->sc_flags &= ~RT2661_DATA_OACTIVE;
 		if (!(sc->sc_flags & (RT2661_MGT_OACTIVE|RT2661_DATA_OACTIVE)))
-			ifp->if_flags &= ~IFF_OACTIVE;
+			ifq_clr_oactive(&ifp->if_snd);
 		rt2661_start(ifp);
 	}
 }
@@ -1928,13 +1928,13 @@ rt2661_start(struct ifnet *ifp)
 	 * net80211 may still try to send management frames even if the
 	 * IFF_RUNNING flag is not set...
 	 */
-	if ((ifp->if_flags & (IFF_RUNNING | IFF_OACTIVE)) != IFF_RUNNING)
+	if (!(ifp->if_flags & IFF_RUNNING) || ifq_is_oactive(&ifp->if_snd))
 		return;
 
 	for (;;) {
 		if (mq_len(&ic->ic_mgtq) > 0) {
 			if (sc->mgtq.queued >= RT2661_MGT_RING_COUNT) {
-				ifp->if_flags |= IFF_OACTIVE;
+				ifq_set_oactive(&ifp->if_snd);
 				break;
 			}
 
@@ -1951,7 +1951,7 @@ rt2661_start(struct ifnet *ifp)
 
 		} else {
 			if (sc->txq[0].queued >= RT2661_TX_RING_COUNT - 1) {
-				ifp->if_flags |= IFF_OACTIVE;
+				ifq_set_oactive(&ifp->if_snd);
 				break;
 			}
 
@@ -2707,8 +2707,8 @@ rt2661_init(struct ifnet *ifp)
 	/* kick Rx */
 	RAL_WRITE(sc, RT2661_RX_CNTL_CSR, 1);
 
-	ifp->if_flags &= ~IFF_OACTIVE;
 	ifp->if_flags |= IFF_RUNNING;
+	ifq_clr_oactive(&ifp->if_snd);
 
 	if (ic->ic_opmode != IEEE80211_M_MONITOR)
 		ieee80211_new_state(ic, IEEE80211_S_SCAN, -1);
@@ -2728,7 +2728,8 @@ rt2661_stop(struct ifnet *ifp, int disable)
 
 	sc->sc_tx_timer = 0;
 	ifp->if_timer = 0;
-	ifp->if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);
+	ifp->if_flags &= ~IFF_RUNNING;
+	ifq_clr_oactive(&ifp->if_snd);
 
 	ieee80211_new_state(ic, IEEE80211_S_INIT, -1);	/* free all nodes */
 	rt2661_amrr_node_free_all(sc);