Big polling(4) cleanup.

o Axe poll in trap.

o Axe IFF_POLLING flag from if_flags.

o Rework revision 1.21 (Giant removal), in such a way that
  poll_mtx is not dropped during call to polling handler.
  This fixes problem with idle polling.

o Make registration and deregistration from polling in a
  functional way, insted of next tick/interrupt.

o Obsolete kern.polling.enable. Polling is turned on/off
  with ifconfig.

Detailed kern_poll.c changes:
  - Remove polling handler flags, introduced in 1.21. The are not
    needed now.
  - Forget and do not check if_flags, if_capenable and if_drv_flags.
  - Call all registered polling handlers unconditionally.
  - Do not drop poll_mtx, when entering polling handlers.
  - In ether_poll() NET_LOCK_GIANT prior to locking poll_mtx.
  - In netisr_poll() axe the block, where polling code asks drivers
    to unregister.
  - In netisr_poll() and ether_poll() do polling always, if any
    handlers are present.
  - In ether_poll_[de]register() remove a lot of error hiding code. Assert
    that arguments are correct, instead.
  - In ether_poll_[de]register() use standard return values in case of
    error or success.
  - Introduce poll_switch() that is a sysctl handler for kern.polling.enable.
    poll_switch() goes through interface list and enabled/disables polling.
    A message that kern.polling.enable is deprecated is printed.

Detailed driver changes:
  - On attach driver announces IFCAP_POLLING in if_capabilities, but
    not in if_capenable.
  - On detach driver calls ether_poll_deregister() if polling is enabled.
  - In polling handler driver obtains its lock and checks IFF_DRV_RUNNING
    flag. If there is no, then unlocks and returns.
  - In ioctl handler driver checks for IFCAP_POLLING flag requested to
    be set or cleared. Driver first calls ether_poll_[de]register(), then
    obtains driver lock and [dis/en]ables interrupts.
  - In interrupt handler driver checks IFCAP_POLLING flag in if_capenable.
    If present, then returns.This is important to protect from spurious
    interrupts.

Reviewed by:	ru, sam, jhb

1 files changed, 44 insertions, 31 deletions

diff --git a/sys/pci/if_sis.c b/sys/pci/if_sis.c
index 117a46a..c0417be 100644
--- a/sys/pci/if_sis.c
+++ b/sys/pci/if_sis.c
@@ -1217,11 +1217,10 @@ sis_attach(device_t dev)
 	 */
 	ifp->if_data.ifi_hdrlen = sizeof(struct ether_vlan_header);
 	ifp->if_capabilities |= IFCAP_VLAN_MTU;
-
+	ifp->if_capenable = ifp->if_capabilities;
 #ifdef DEVICE_POLLING
 	ifp->if_capabilities |= IFCAP_POLLING;
 #endif
-	ifp->if_capenable = ifp->if_capabilities;
 
 	/* Hook interrupt last to avoid having to lock softc */
 	error = bus_setup_intr(dev, sc->sis_res[1], INTR_TYPE_NET | INTR_MPSAFE,
@@ -1257,6 +1256,11 @@ sis_detach(device_t dev)
 	KASSERT(mtx_initialized(&sc->sis_mtx), ("sis mutex not initialized"));
 	ifp = sc->sis_ifp;
 
+#ifdef DEVICE_POLLING
+	if (ifp->if_capenable & IFCAP_POLLING)
+		ether_poll_deregister(ifp);
+#endif
+
 	/* These should only be active if attach succeeded. */
 	if (device_is_attached(dev)) {
 		SIS_LOCK(sc);
@@ -1404,12 +1408,12 @@ sis_rxeof(struct sis_softc *sc)
 	    cur_rx = cur_rx->sis_nextdesc) {
 
 #ifdef DEVICE_POLLING
-		if (ifp->if_flags & IFF_POLLING) {
+		if (ifp->if_capenable & IFCAP_POLLING) {
 			if (sc->rxcycles <= 0)
 				break;
 			sc->rxcycles--;
 		}
-#endif /* DEVICE_POLLING */
+#endif
 		rxstat = cur_rx->sis_rxstat;
 		bus_dmamap_sync(sc->sis_tag,
 		    cur_rx->sis_map, BUS_DMASYNC_POSTWRITE);
@@ -1574,13 +1578,9 @@ sis_poll(struct ifnet *ifp, enum poll_cmd cmd, int count)
 	struct	sis_softc *sc = ifp->if_softc;
 
 	SIS_LOCK(sc);
-	if (!(ifp->if_capenable & IFCAP_POLLING)) {
-		ether_poll_deregister(ifp);
-		cmd = POLL_DEREGISTER;
-	}
-	if (cmd == POLL_DEREGISTER) { /* final call, enable interrupts */
-		CSR_WRITE_4(sc, SIS_IER, 1);
-		goto done;
+	if (!(ifp->if_drv_flags & IFF_DRV_RUNNING)) {
+		SIS_UNLOCK(sc);
+		return;
 	}
 
 	/*
@@ -1613,7 +1613,7 @@ sis_poll(struct ifnet *ifp, enum poll_cmd cmd, int count)
 			sis_initl(sc);
 		}
 	}
-done:
+
 	SIS_UNLOCK(sc);
 }
 #endif /* DEVICE_POLLING */
@@ -1633,14 +1633,11 @@ sis_intr(void *arg)
 
 	SIS_LOCK(sc);
 #ifdef DEVICE_POLLING
-	if (ifp->if_flags & IFF_POLLING)
-		goto done;
-	if ((ifp->if_capenable & IFCAP_POLLING) &&
-	    ether_poll_register(sis_poll, ifp)) { /* ok, disable interrupts */
-		CSR_WRITE_4(sc, SIS_IER, 0);
-		goto done;
+	if (ifp->if_capenable & IFCAP_POLLING) {
+		SIS_UNLOCK(sc);
+		return;
 	}
-#endif /* DEVICE_POLLING */
+#endif
 
 	/* Disable interrupts. */
 	CSR_WRITE_4(sc, SIS_IER, 0);
@@ -1679,9 +1676,6 @@ sis_intr(void *arg)
 	if (!IFQ_DRV_IS_EMPTY(&ifp->if_snd))
 		sis_startl(ifp);
 
-#ifdef DEVICE_POLLING
-done:
-#endif /* DEVICE_POLLING */
 	SIS_UNLOCK(sc);
 }
 
@@ -2033,10 +2027,10 @@ sis_initl(struct sis_softc *sc)
 	 * ... only enable interrupts if we are not polling, make sure
 	 * they are off otherwise.
 	 */
-	if (ifp->if_flags & IFF_POLLING)
+	if (ifp->if_capenable & IFCAP_POLLING)
 		CSR_WRITE_4(sc, SIS_IER, 0);
 	else
-#endif /* DEVICE_POLLING */
+#endif
 	CSR_WRITE_4(sc, SIS_IER, 1);
 
 	/* Enable receiver and transmitter. */
@@ -2133,10 +2127,32 @@ sis_ioctl(struct ifnet *ifp, u_long command, caddr_t data)
 		error = ifmedia_ioctl(ifp, ifr, &mii->mii_media, command);
 		break;
 	case SIOCSIFCAP:
-		SIS_LOCK(sc);
-		ifp->if_capenable &= ~IFCAP_POLLING;
-		ifp->if_capenable |= ifr->ifr_reqcap & IFCAP_POLLING;
-		SIS_UNLOCK(sc);
+		/* ok, disable interrupts */
+#ifdef DEVICE_POLLING
+		if (ifr->ifr_reqcap & IFCAP_POLLING &&
+		    !(ifp->if_capenable & IFCAP_POLLING)) {
+			error = ether_poll_register(sis_poll, ifp);
+			if (error)
+				return(error);
+			SIS_LOCK(sc);
+			/* Disable interrupts */
+			CSR_WRITE_4(sc, SIS_IER, 0);
+			ifp->if_capenable |= IFCAP_POLLING;
+			SIS_UNLOCK(sc);
+			return (error);
+			
+		}
+		if (!(ifr->ifr_reqcap & IFCAP_POLLING) &&
+		    ifp->if_capenable & IFCAP_POLLING) {
+			error = ether_poll_deregister(ifp);
+			/* Enable interrupts. */
+			SIS_LOCK(sc);
+			CSR_WRITE_4(sc, SIS_IER, 1);
+			ifp->if_capenable &= ~IFCAP_POLLING;
+			SIS_UNLOCK(sc);
+			return (error);
+		}
+#endif /* DEVICE_POLLING */
 		break;
 	default:
 		error = ether_ioctl(ifp, command, data);
@@ -2192,9 +2208,6 @@ sis_stop(struct sis_softc *sc)
 	callout_stop(&sc->sis_stat_ch);
 
 	ifp->if_drv_flags &= ~(IFF_DRV_RUNNING | IFF_DRV_OACTIVE);
-#ifdef DEVICE_POLLING
-	ether_poll_deregister(ifp);
-#endif
 	CSR_WRITE_4(sc, SIS_IER, 0);
 	CSR_WRITE_4(sc, SIS_IMR, 0);
 	CSR_READ_4(sc, SIS_ISR); /* clear any interrupts already pending */