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, 8 insertions, 7 deletions

diff --git a/sys/dev/usb/if_udav.c b/sys/dev/usb/if_udav.c
index 8b577c0b750..f3b378f2bbc 100644
--- a/sys/dev/usb/if_udav.c
+++ b/sys/dev/usb/if_udav.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_udav.c,v 1.76 2015/11/24 17:11:40 mpi Exp $ */
+/*	$OpenBSD: if_udav.c,v 1.77 2015/11/25 03:10:00 dlg Exp $ */
 /*	$NetBSD: if_udav.c,v 1.3 2004/04/23 17:25:25 itojun Exp $	*/
 /*	$nabe: if_udav.c,v 1.3 2003/08/21 16:57:19 nabe Exp $	*/
 /*
@@ -646,7 +646,7 @@ udav_init(struct ifnet *ifp)
 	}
 
 	ifp->if_flags |= IFF_RUNNING;
-	ifp->if_flags &= ~IFF_OACTIVE;
+	ifq_clr_oactive(&ifp->if_snd);
 
 	splx(s);
 
@@ -913,7 +913,7 @@ udav_start(struct ifnet *ifp)
 	if (!sc->sc_link)
 		return;
 
-	if (ifp->if_flags & IFF_OACTIVE)
+	if (ifq_is_oactive(&ifp->if_snd))
 		return;
 
 	m_head = ifq_deq_begin(&ifp->if_snd);
@@ -922,7 +922,7 @@ udav_start(struct ifnet *ifp)
 
 	if (udav_send(sc, m_head, 0)) {
 		ifq_deq_rollback(&ifp->if_snd, m_head);
-		ifp->if_flags |= IFF_OACTIVE;
+		ifq_set_oactive(&ifp->if_snd);
 		return;
 	}
 
@@ -933,7 +933,7 @@ udav_start(struct ifnet *ifp)
 		bpf_mtap(ifp->if_bpf, m_head, BPF_DIRECTION_OUT);
 #endif
 
-	ifp->if_flags |= IFF_OACTIVE;
+	ifq_set_oactive(&ifp->if_snd);
 
 	/* Set a timeout in case the chip goes out to lunch. */
 	ifp->if_timer = 5;
@@ -1007,7 +1007,7 @@ udav_txeof(struct usbd_xfer *xfer, void *priv, usbd_status status)
 	DPRINTF(("%s: %s: enter\n", sc->sc_dev.dv_xname, __func__));
 
 	ifp->if_timer = 0;
-	ifp->if_flags &= ~IFF_OACTIVE;
+	ifq_clr_oactive(&ifp->if_snd);
 
 	if (status != USBD_NORMAL_COMPLETION) {
 		if (status == USBD_NOT_STARTED || status == USBD_CANCELLED) {
@@ -1220,7 +1220,8 @@ udav_stop(struct ifnet *ifp, int disable)
 	DPRINTF(("%s: %s: enter\n", sc->sc_dev.dv_xname, __func__));
 
 	ifp->if_timer = 0;
-	ifp->if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);
+	ifp->if_flags &= ~IFF_RUNNING;
+	ifq_clr_oactive(&ifp->if_snd);
 
 	udav_reset(sc);