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, 7 insertions, 6 deletions

diff --git a/sys/dev/ic/acx.c b/sys/dev/ic/acx.c
index b84a7d6a60c..ec24038e630 100644
--- a/sys/dev/ic/acx.c
+++ b/sys/dev/ic/acx.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: acx.c,v 1.116 2015/11/24 17:11:39 mpi Exp $ */
+/*	$OpenBSD: acx.c,v 1.117 2015/11/25 03:09:58 dlg Exp $ */
 
 /*
  * Copyright (c) 2006 Jonathan Gray <jsg@openbsd.org>
@@ -477,7 +477,7 @@ acx_init(struct ifnet *ifp)
 	acx_enable_intr(sc);
 
 	ifp->if_flags |= IFF_RUNNING;
-	ifp->if_flags &= ~IFF_OACTIVE;
+	ifq_clr_oactive(&ifp->if_snd);
 
 	if (ic->ic_opmode != IEEE80211_M_MONITOR)
 		/* start background scanning */
@@ -610,7 +610,8 @@ acx_stop(struct acx_softc *sc)
 
 	sc->sc_txtimer = 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(&sc->sc_ic, IEEE80211_S_INIT, -1);
 
 	/* disable card if possible */
@@ -910,7 +911,7 @@ acx_start(struct ifnet *ifp)
 
 	if ((sc->sc_flags & ACX_FLAG_FW_LOADED) == 0 ||
 	    (ifp->if_flags & IFF_RUNNING) == 0 ||
-	    (ifp->if_flags & IFF_OACTIVE))
+	    ifq_is_oactive(&ifp->if_snd))
 		return;
 
 	/*
@@ -1066,7 +1067,7 @@ encapped:
 	bd->tx_free_start = idx;
 
 	if (bd->tx_used_count == ACX_TX_DESC_CNT)
-		ifp->if_flags |= IFF_OACTIVE;
+		ifq_set_oactive(&ifp->if_snd);
 
 	if (trans && sc->sc_txtimer == 0)
 		sc->sc_txtimer = 5;
@@ -1216,7 +1217,7 @@ acx_txeof(struct acx_softc *sc)
 	sc->sc_txtimer = bd->tx_used_count == 0 ? 0 : 5;
 
 	if (bd->tx_used_count != ACX_TX_DESC_CNT) {
-		ifp->if_flags &= ~IFF_OACTIVE;
+		ifq_clr_oactive(&ifp->if_snd);
 		acx_start(ifp);
 	}
 }