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/pci/if_iwm.c b/sys/dev/pci/if_iwm.c
index 94ab7e188e0..92f9828066d 100644
--- a/sys/dev/pci/if_iwm.c
+++ b/sys/dev/pci/if_iwm.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_iwm.c,v 1.67 2015/11/24 17:11:39 mpi Exp $	*/
+/*	$OpenBSD: if_iwm.c,v 1.68 2015/11/25 03:09:59 dlg Exp $	*/
 
 /*
  * Copyright (c) 2014 genua mbh <info@genua.de>
@@ -3175,8 +3175,8 @@ iwm_mvm_rx_tx_cmd(struct iwm_softc *sc,
 
 	if (--ring->queued < IWM_TX_RING_LOMARK) {
 		sc->qfullmsk &= ~(1 << ring->qid);
-		if (sc->qfullmsk == 0 && (ifp->if_flags & IFF_OACTIVE)) {
-			ifp->if_flags &= ~IFF_OACTIVE;
+		if (sc->qfullmsk == 0 && ifq_is_oactive(&ifp->if_snd)) {
+			ifq_clr_oactive(&ifp->if_snd);
 			/*
 			 * Well, we're in interrupt context, but then again
 			 * I guess net80211 does all sorts of stunts in
@@ -5552,7 +5552,7 @@ iwm_init(struct ifnet *ifp)
  	 * Ok, firmware loaded and we are jogging
 	 */
 
-	ifp->if_flags &= ~IFF_OACTIVE;
+	ifq_clr_oactive(&ifp->if_snd);
 	ifp->if_flags |= IFF_RUNNING;
 
 	ieee80211_begin_scan(ifp);
@@ -5575,13 +5575,13 @@ iwm_start(struct ifnet *ifp)
 	struct mbuf *m;
 	int ac = EDCA_AC_BE; /* XXX */
 
-	if ((ifp->if_flags & (IFF_RUNNING | IFF_OACTIVE)) != IFF_RUNNING)
+	if (!(ifp->if_flags & IFF_RUNNING) || ifq_is_oactive(&ifp->if_snd))
 		return;
 
 	for (;;) {
 		/* why isn't this done per-queue? */
 		if (sc->qfullmsk != 0) {
-			ifp->if_flags |= IFF_OACTIVE;
+			ifq_set_oactive(&ifp->if_snd);
 			break;
 		}
 
@@ -5644,7 +5644,8 @@ iwm_stop(struct ifnet *ifp, int disable)
 	sc->sc_scanband = 0;
 	sc->sc_auth_prot = 0;
 	ic->ic_scan_lock = IEEE80211_SCAN_UNLOCKED;
-	ifp->if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);
+	ifp->if_flags &= ~IFF_RUNNING;
+	ifq_clr_oactive(&ifp->if_snd);
 
 	task_del(systq, &sc->init_task);
 	task_del(sc->sc_nswq, &sc->newstate_task);