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@

2 files changed, 12 insertions, 12 deletions

diff --git a/sys/dev/sbus/be.c b/sys/dev/sbus/be.c
index a6e58d7ffa4..dacb19acb80 100644
--- a/sys/dev/sbus/be.c
+++ b/sys/dev/sbus/be.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: be.c,v 1.37 2015/11/24 17:11:40 mpi Exp $	*/
+/*	$OpenBSD: be.c,v 1.38 2015/11/25 03:09:59 dlg Exp $	*/
 /*	$NetBSD: be.c,v 1.26 2001/03/20 15:39:20 pk Exp $	*/
 
 /*-
@@ -570,7 +570,7 @@ bestart(struct ifnet *ifp)
 	unsigned int bix, len;
 	unsigned int ntbuf = sc->sc_rb.rb_ntbuf;
 
-	if ((ifp->if_flags & (IFF_RUNNING | IFF_OACTIVE)) != IFF_RUNNING)
+	if (!(ifp->if_flags & IFF_RUNNING) || ifq_is_oactive(&ifp->if_snd))
 		return;
 
 	bix = sc->sc_rb.rb_tdhead;
@@ -606,7 +606,7 @@ bestart(struct ifnet *ifp)
 			bix = 0;
 
 		if (++sc->sc_rb.rb_td_nbusy == ntbuf) {
-			ifp->if_flags |= IFF_OACTIVE;
+			ifq_set_oactive(&ifp->if_snd);
 			break;
 		}
 	}
@@ -851,7 +851,7 @@ betint(struct be_softc *sc)
 		if (txflags & QEC_XD_OWN)
 			break;
 
-		ifp->if_flags &= ~IFF_OACTIVE;
+		ifq_clr_oactive(&ifp->if_snd);
 		ifp->if_opackets++;
 
 		if (++bix == QEC_XD_RING_MAXSIZE)
@@ -1060,7 +1060,7 @@ beinit(struct be_softc *sc)
 	bus_space_write_4(t, br, BE_BRI_RXCFG, v);
 
 	ifp->if_flags |= IFF_RUNNING;
-	ifp->if_flags &= ~IFF_OACTIVE;
+	ifq_clr_oactive(&ifp->if_snd);
 
 	be_ifmedia_upd(ifp);
 	timeout_add_sec(&sc->sc_tick_ch, 1);
diff --git a/sys/dev/sbus/qe.c b/sys/dev/sbus/qe.c
index 12bfbc56a7d..108f64047de 100644
--- a/sys/dev/sbus/qe.c
+++ b/sys/dev/sbus/qe.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: qe.c,v 1.35 2015/11/24 17:11:40 mpi Exp $	*/
+/*	$OpenBSD: qe.c,v 1.36 2015/11/25 03:09:59 dlg Exp $	*/
 /*	$NetBSD: qe.c,v 1.16 2001/03/30 17:30:18 christos Exp $	*/
 
 /*-
@@ -442,7 +442,7 @@ qestart(ifp)
 	unsigned int bix, len;
 	unsigned int ntbuf = sc->sc_rb.rb_ntbuf;
 
-	if ((ifp->if_flags & (IFF_RUNNING | IFF_OACTIVE)) != IFF_RUNNING)
+	if (!(ifp->if_flags & IFF_RUNNING) || ifq_is_oactive(&ifp->if_snd))
 		return;
 
 	bix = sc->sc_rb.rb_tdhead;
@@ -479,7 +479,7 @@ qestart(ifp)
 			bix = 0;
 
 		if (++sc->sc_rb.rb_td_nbusy == ntbuf) {
-			ifp->if_flags |= IFF_OACTIVE;
+			ifq_set_oactive(&ifp->if_snd);
 			break;
 		}
 	}
@@ -628,7 +628,7 @@ qe_tint(sc)
 		if (txflags & QEC_XD_OWN)
 			break;
 
-		ifp->if_flags &= ~IFF_OACTIVE;
+		ifq_clr_oactive(&ifp->if_snd);
 		ifp->if_opackets++;
 
 		if (++bix == QEC_XD_RING_MAXSIZE)
@@ -642,8 +642,8 @@ qe_tint(sc)
 
 	if (sc->sc_rb.rb_tdtail != bix) {
 		sc->sc_rb.rb_tdtail = bix;
-		if (ifp->if_flags & IFF_OACTIVE) {
-			ifp->if_flags &= ~IFF_OACTIVE;
+		if (ifq_is_oactive(&ifp->if_snd)) {
+			ifq_clr_oactive(&ifp->if_snd);
 			qestart(ifp);
 		}
 	}
@@ -1039,7 +1039,7 @@ qeinit(sc)
 	qe_mcreset(sc);
 
 	ifp->if_flags |= IFF_RUNNING;
-	ifp->if_flags &= ~IFF_OACTIVE;
+	ifq_clr_oactive(&ifp->if_snd);
 	splx(s);
 }