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, 9 insertions, 7 deletions

diff --git a/sys/dev/usb/if_otus.c b/sys/dev/usb/if_otus.c
index 52df4d0ac56..d978d70f520 100644
--- a/sys/dev/usb/if_otus.c
+++ b/sys/dev/usb/if_otus.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_otus.c,v 1.50 2015/11/24 13:45:06 mpi Exp $	*/
+/*	$OpenBSD: if_otus.c,v 1.51 2015/11/25 03:10:00 dlg Exp $	*/
 
 /*-
  * Copyright (c) 2009 Damien Bergamini <damien.bergamini@free.fr>
@@ -244,7 +244,8 @@ otus_detach(struct device *self, int flags)
 	usbd_ref_wait(sc->sc_udev);
 
 	if (ifp->if_softc != NULL) {
-		ifp->if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);
+		ifp->if_flags &= ~IFF_RUNNING;
+		ifq_clr_oactive(&ifp->if_snd);
 		ieee80211_ifdetach(ifp);
 		if_detach(ifp);
 	}
@@ -1267,7 +1268,7 @@ otus_txeof(struct usbd_xfer *xfer, void *priv, usbd_status status)
 	}
 	sc->sc_tx_timer = 0;
 	ifp->if_opackets++;
-	ifp->if_flags &= ~IFF_OACTIVE;
+	ifq_clr_oactive(&ifp->if_snd);
 	otus_start(ifp);
 	splx(s);
 }
@@ -1405,12 +1406,12 @@ otus_start(struct ifnet *ifp)
 	struct ieee80211_node *ni;
 	struct mbuf *m;
 
-	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 (sc->tx_queued >= OTUS_TX_DATA_LIST_COUNT) {
-			ifp->if_flags |= IFF_OACTIVE;
+			ifq_set_oactive(&ifp->if_snd);
 			break;
 		}
 		/* Send pending management frames first. */
@@ -2286,8 +2287,8 @@ otus_init(struct ifnet *ifp)
 	otus_write(sc, 0x1c3d30, 0x100);
 	(void)otus_write_barrier(sc);
 
-	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_RUN, -1);
@@ -2306,7 +2307,8 @@ otus_stop(struct ifnet *ifp)
 
 	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);
 
 	timeout_del(&sc->scan_to);
 	timeout_del(&sc->calib_to);