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_wb.c b/sys/dev/pci/if_wb.c
index 8cf4c154d8f..ea52e9a4bf9 100644
--- a/sys/dev/pci/if_wb.c
+++ b/sys/dev/pci/if_wb.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_wb.c,v 1.65 2015/11/24 17:11:39 mpi Exp $	*/
+/*	$OpenBSD: if_wb.c,v 1.66 2015/11/25 03:09:59 dlg Exp $	*/
 
 /*
  * Copyright (c) 1997, 1998
@@ -1065,7 +1065,7 @@ void wb_txeoc(sc)
 	ifp->if_timer = 0;
 
 	if (sc->wb_cdata.wb_tx_head == NULL) {
-		ifp->if_flags &= ~IFF_OACTIVE;
+		ifq_clr_oactive(&ifp->if_snd);
 		sc->wb_cdata.wb_tx_tail = NULL;
 	} else {
 		if (WB_TXOWN(sc->wb_cdata.wb_tx_head) == WB_UNSENT) {
@@ -1285,7 +1285,7 @@ void wb_start(ifp)
 	 * punt.
 	 */
 	if (sc->wb_cdata.wb_tx_free->wb_mbuf != NULL) {
-		ifp->if_flags |= IFF_OACTIVE;
+		ifq_set_oactive(&ifp->if_snd);
 		return;
 	}
 
@@ -1468,7 +1468,7 @@ void wb_init(xsc)
 	WB_SETBIT(sc, WB_NETCFG, WB_NETCFG_TX_ON);
 
 	ifp->if_flags |= IFF_RUNNING;
-	ifp->if_flags &= ~IFF_OACTIVE;
+	ifq_clr_oactive(&ifp->if_snd);
 
 	splx(s);
 
@@ -1593,7 +1593,8 @@ void wb_stop(sc)
 
 	timeout_del(&sc->wb_tick_tmo);
 
-	ifp->if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);
+	ifp->if_flags &= ~IFF_RUNNING;
+	ifq_clr_oactive(&ifp->if_snd);
 
 	WB_CLRBIT(sc, WB_NETCFG, (WB_NETCFG_RX_ON|WB_NETCFG_TX_ON));
 	CSR_WRITE_4(sc, WB_IMR, 0x00000000);