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/arch/armv7/sunxi/sxie.c b/sys/arch/armv7/sunxi/sxie.c
index c74bbaf7d19..062b0d06337 100644
--- a/sys/arch/armv7/sunxi/sxie.c
+++ b/sys/arch/armv7/sunxi/sxie.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sxie.c,v 1.12 2015/11/24 17:11:38 mpi Exp $	*/
+/*	$OpenBSD: sxie.c,v 1.13 2015/11/25 03:09:58 dlg Exp $	*/
 /*
  * Copyright (c) 2012-2013 Patrick Wildt <patrick@blueri.se>
  * Copyright (c) 2013 Artturi Alm
@@ -396,7 +396,7 @@ sxie_init(struct sxie_softc *sc)
 
 	/* Indicate we are up and running. */
 	ifp->if_flags |= IFF_RUNNING;
-	ifp->if_flags &= ~IFF_OACTIVE;
+	ifq_clr_oactive(&ifp->if_snd);
 
 	SXISET4(sc, SXIE_INTCR, SXIE_INTR_ENABLE);
 
@@ -426,7 +426,7 @@ sxie_intr(void *arg)
 	pending &= 3;
 
 	if (pending) {
-		ifp->if_flags &= ~IFF_OACTIVE;
+		ifq_clr_oactive(&ifp->if_snd);
 		sc->txf_inuse--;
 		ifp->if_opackets++;
 		if (pending == 3) { /* 2 packets got sent */
@@ -461,9 +461,9 @@ sxie_start(struct ifnet *ifp)
 	uint32_t txbuf[SXIE_MAX_PKT_SIZE / sizeof(uint32_t)]; /* XXX !!! */
 
 	if (sc->txf_inuse > 1)
-		ifp->if_flags |= IFF_OACTIVE;
+		ifq_set_oactive(&ifp->if_snd);
 
-	if ((ifp->if_flags & (IFF_OACTIVE | IFF_RUNNING)) != IFF_RUNNING)
+	if (!(ifp->if_flags & IFF_RUNNING) || ifq_is_oactive(&ifp->if_snd))
 		return;
 
 	td = (uint8_t *)&txbuf[0];
@@ -484,7 +484,7 @@ trynext:
 	if (sc->txf_inuse > 1) {
 		ifq_deq_rollback(&ifp->if_snd, m);
 		printf("sxie_start: tx fifos in use.\n");
-		ifp->if_flags |= IFF_OACTIVE;
+		ifq_set_oactive(&ifp->if_snd);
 		return;
 	}
 
@@ -524,8 +524,9 @@ sxie_stop(struct sxie_softc *sc)
 
 	sxie_reset(sc);
 
-	ifp->if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);
+	ifp->if_flags &= ~IFF_RUNNING;
 	ifp->if_timer = 0;
+	ifq_clr_oactive(&ifp->if_snd);
 }
 
 void