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/arch/octeon/dev/if_cnmac.c b/sys/arch/octeon/dev/if_cnmac.c
index c31b889c85a..f7ac8d6fd63 100644
--- a/sys/arch/octeon/dev/if_cnmac.c
+++ b/sys/arch/octeon/dev/if_cnmac.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_cnmac.c,v 1.34 2015/11/24 17:11:38 mpi Exp $	*/
+/*	$OpenBSD: if_cnmac.c,v 1.35 2015/11/25 03:09:58 dlg Exp $	*/
 
 /*
  * Copyright (c) 2007 Internet Initiative Japan, Inc.
@@ -1006,7 +1006,7 @@ octeon_eth_start(struct ifnet *ifp)
 	 */
 	octeon_eth_send_queue_flush_prefetch(sc);
 
-	if ((ifp->if_flags & (IFF_RUNNING | IFF_OACTIVE)) != IFF_RUNNING)
+	if (!(ifp->if_flags & IFF_RUNNING) || ifq_is_oactive(&ifp->if_snd))
 		goto last;
 
 	if (__predict_false(!cn30xxgmx_link_status(sc->sc_gmx_port)))
@@ -1063,7 +1063,7 @@ octeon_eth_watchdog(struct ifnet *ifp)
 	octeon_eth_configure(sc);
 
 	SET(ifp->if_flags, IFF_RUNNING);
-	CLR(ifp->if_flags, IFF_OACTIVE);
+	ifq_clr_oactive(&ifp->if_snd);
 	ifp->if_timer = 0;
 
 	octeon_eth_start(ifp);
@@ -1097,7 +1097,7 @@ octeon_eth_init(struct ifnet *ifp)
 	timeout_add_sec(&sc->sc_tick_free_ch, 1);
 
 	SET(ifp->if_flags, IFF_RUNNING);
-	CLR(ifp->if_flags, IFF_OACTIVE);
+	ifq_clr_oactive(&ifp->if_snd);
 
 	return 0;
 }
@@ -1116,7 +1116,8 @@ octeon_eth_stop(struct ifnet *ifp, int disable)
 	cn30xxgmx_port_enable(sc->sc_gmx_port, 0);
 
 	/* Mark the interface as down and cancel the watchdog timer. */
-	CLR(ifp->if_flags, IFF_RUNNING | IFF_OACTIVE);
+	CLR(ifp->if_flags, IFF_RUNNING);
+	ifq_clr_oactive(&ifp->if_snd);
 	ifp->if_timer = 0;
 
 	intr_barrier(octeon_eth_pow_recv_ih);