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, 6 insertions, 5 deletions

diff --git a/sys/dev/pci/if_sk.c b/sys/dev/pci/if_sk.c
index b10761ea93b..b672cfa0808 100644
--- a/sys/dev/pci/if_sk.c
+++ b/sys/dev/pci/if_sk.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_sk.c,v 1.182 2015/11/24 17:11:39 mpi Exp $	*/
+/*	$OpenBSD: if_sk.c,v 1.183 2015/11/25 03:09:59 dlg Exp $	*/
 
 /*
  * Copyright (c) 1997, 1998, 1999, 2000
@@ -1507,7 +1507,7 @@ sk_start(struct ifnet *ifp)
 		 */
 		if (sk_encap(sc_if, m_head, &idx)) {
 			ifq_deq_rollback(&ifp->if_snd, m_head);
-			ifp->if_flags |= IFF_OACTIVE;
+			ifq_set_oactive(&ifp->if_snd);
 			break;
 		}
 
@@ -1695,7 +1695,7 @@ sk_txeof(struct sk_if_softc *sc_if)
 	ifp->if_timer = sc_if->sk_cdata.sk_tx_cnt > 0 ? 5 : 0;
 
 	if (sc_if->sk_cdata.sk_tx_cnt < SK_TX_RING_CNT - 2)
-		ifp->if_flags &= ~IFF_OACTIVE;
+		ifq_clr_oactive(&ifp->if_snd);
 
 	sc_if->sk_cdata.sk_tx_cons = idx;
 }
@@ -2396,7 +2396,7 @@ sk_init(void *xsc_if)
 	CSR_WRITE_4(sc, sc_if->sk_tx_bmu, SK_TXBMU_TX_START);
 
 	ifp->if_flags |= IFF_RUNNING;
-	ifp->if_flags &= ~IFF_OACTIVE;
+	ifq_clr_oactive(&ifp->if_snd);
 
 	if (SK_IS_YUKON(sc))
 		timeout_add_sec(&sc_if->sk_tick_ch, 1);
@@ -2418,7 +2418,8 @@ sk_stop(struct sk_if_softc *sc_if, int softonly)
 
 	timeout_del(&sc_if->sk_tick_ch);
 
-	ifp->if_flags &= ~(IFF_RUNNING|IFF_OACTIVE);
+	ifp->if_flags &= ~IFF_RUNNING;
+	ifq_clr_oactive(&ifp->if_snd);
 
 	if (!softonly) {
 		/* stop Tx descriptor polling timer */