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/usb/if_ral.c b/sys/dev/usb/if_ral.c
index 75e9e4a8186..ecd6bb4a01d 100644
--- a/sys/dev/usb/if_ral.c
+++ b/sys/dev/usb/if_ral.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_ral.c,v 1.137 2015/11/24 13:45:06 mpi Exp $	*/
+/*	$OpenBSD: if_ral.c,v 1.138 2015/11/25 03:10:00 dlg Exp $	*/
 
 /*-
  * Copyright (c) 2005, 2006
@@ -693,7 +693,7 @@ ural_txeof(struct usbd_xfer *xfer, void *priv, usbd_status status)
 	DPRINTFN(10, ("tx done\n"));
 
 	sc->sc_tx_timer = 0;
-	ifp->if_flags &= ~IFF_OACTIVE;
+	ifq_clr_oactive(&ifp->if_snd);
 	ural_start(ifp);
 
 	splx(s);
@@ -1232,12 +1232,12 @@ ural_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 (sc->tx_queued >= RAL_TX_LIST_COUNT - 1) {
-			ifp->if_flags |= IFF_OACTIVE;
+			ifq_set_oactive(&ifp->if_snd);
 			break;
 		}
 
@@ -2056,7 +2056,7 @@ ural_init(struct ifnet *ifp)
 	}
 	ural_write(sc, RAL_TXRX_CSR2, tmp);
 
-	ifp->if_flags &= ~IFF_OACTIVE;
+	ifq_clr_oactive(&ifp->if_snd);
 	ifp->if_flags |= IFF_RUNNING;
 
 	if (ic->ic_opmode == IEEE80211_M_MONITOR)
@@ -2078,7 +2078,8 @@ ural_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 */