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/arch/socppc/dev/if_tsec.c b/sys/arch/socppc/dev/if_tsec.c
index 28976795850..c2eea96903f 100644
--- a/sys/arch/socppc/dev/if_tsec.c
+++ b/sys/arch/socppc/dev/if_tsec.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_tsec.c,v 1.41 2015/11/24 13:33:18 mpi Exp $	*/
+/*	$OpenBSD: if_tsec.c,v 1.42 2015/11/25 03:09:58 dlg Exp $	*/
 
 /*
  * Copyright (c) 2008 Mark Kettenis
@@ -517,7 +517,7 @@ tsec_start(struct ifnet *ifp)
 
 	if (!(ifp->if_flags & IFF_RUNNING))
 		return;
-	if (ifp->if_flags & IFF_OACTIVE)
+	if (ifq_is_oactive(&ifp->if_snd))
 		return;
 	if (IFQ_IS_EMPTY(&ifp->if_snd))
 		return;
@@ -533,7 +533,7 @@ tsec_start(struct ifnet *ifp)
 		error = tsec_encap(sc, m, &idx);
 		if (error == ENOBUFS) {
 			ifq_deq_rollback(&ifp->if_snd, m);
-			ifp->if_flags |= IFF_OACTIVE;
+			ifq_set_oactive(&ifp->if_snd);
 			break;
 		} 
 		if (error == EFBIG) {
@@ -828,7 +828,7 @@ tsec_tx_proc(struct tsec_softc *sc)
 			ifp->if_opackets++;
 		}
 
-		ifp->if_flags &= ~IFF_OACTIVE;
+		ifq_clr_oactive(&ifp->if_snd);
 
 		sc->sc_tx_cnt--;
 
@@ -1031,7 +1031,7 @@ tsec_up(struct tsec_softc *sc)
 	tsec_iff(sc);
 
 	ifp->if_flags |= IFF_RUNNING;
-	ifp->if_flags &= ~IFF_OACTIVE;
+	ifq_clr_oactive(&ifp->if_snd);
 
 	tsec_write(sc, TSEC_IMASK, TSEC_IMASK_TXEEN |
 	    TSEC_IMASK_TXBEN | TSEC_IMASK_TXFEN |
@@ -1050,7 +1050,8 @@ tsec_down(struct tsec_softc *sc)
 
 	timeout_del(&sc->sc_tick);
 
-	ifp->if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);
+	ifp->if_flags &= ~IFF_RUNNING;
+	ifq_clr_oactive(&ifp->if_snd);
 	ifp->if_timer = 0;
 
 	tsec_stop_dma(sc);