Switch gem(4) over to using MCLGETI when allocating mbufs for the rx ring.

help from dlg@, tested by a few, ok dlg@

2 files changed, 46 insertions, 65 deletions

diff --git a/sys/dev/ic/gem.c b/sys/dev/ic/gem.c
index 08620c290ce..c81f1f3319f 100644
--- a/sys/dev/ic/gem.c
+++ b/sys/dev/ic/gem.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: gem.c,v 1.85 2008/12/10 20:37:48 brad Exp $	*/
+/*	$OpenBSD: gem.c,v 1.86 2008/12/14 21:31:50 kettenis Exp $	*/
 /*	$NetBSD: gem.c,v 1.1 2001/09/16 00:11:43 eeh Exp $ */
 
 /*
@@ -98,6 +98,7 @@ int		gem_reset_tx(struct gem_softc *);
 int		gem_disable_rx(struct gem_softc *);
 int		gem_disable_tx(struct gem_softc *);
 void		gem_rxdrain(struct gem_softc *);
+void		gem_fill_rx_ring(struct gem_softc *);
 int		gem_add_rxbuf(struct gem_softc *, int idx);
 void		gem_setladrf(struct gem_softc *);
 
@@ -227,6 +228,9 @@ gem_config(struct gem_softc *sc)
 	IFQ_SET_MAXLEN(&ifp->if_snd, GEM_NTXDESC - 1);
 	IFQ_SET_READY(&ifp->if_snd);
 
+	/* Hardware reads RX descriptors in multiples of four. */
+	m_clsetlwm(ifp, MCLBYTES, 4);
+
 	ifp->if_capabilities = IFCAP_VLAN_MTU;
 
 	/* Initialize ifmedia structures and MII info */
@@ -475,6 +479,7 @@ gem_rxdrain(struct gem_softc *sc)
 			rxs->rxs_mbuf = NULL;
 		}
 	}
+	sc->sc_rx_prod = sc->sc_rx_cons = sc->sc_rx_cnt = 0;
 }
 
 /*
@@ -630,8 +635,7 @@ gem_disable_tx(struct gem_softc *sc)
 int
 gem_meminit(struct gem_softc *sc)
 {
-	struct gem_rxsoft *rxs;
-	int i, error;
+	int i;
 
 	/*
 	 * Initialize the transmit descriptor ring.
@@ -648,23 +652,10 @@ gem_meminit(struct gem_softc *sc)
 	 * descriptor rings.
 	 */
 	for (i = 0; i < GEM_NRXDESC; i++) {
-		rxs = &sc->sc_rxsoft[i];
-		if (rxs->rxs_mbuf == NULL) {
-			if ((error = gem_add_rxbuf(sc, i)) != 0) {
-				printf("%s: unable to allocate or map rx "
-				    "buffer %d, error = %d\n",
-				    sc->sc_dev.dv_xname, i, error);
-				/*
-				 * XXX Should attempt to run with fewer receive
-				 * XXX buffers instead of just failing.
-				 */
-				gem_rxdrain(sc);
-				return (1);
-			}
-		} else
-			GEM_INIT_RXDESC(sc, i);
+		sc->sc_rxdescs[i].gd_flags = 0;
+		sc->sc_rxdescs[i].gd_addr = 0;
 	}
-	sc->sc_rxptr = 0;
+	gem_fill_rx_ring(sc);
 
 	return (0);
 }
@@ -810,9 +801,8 @@ gem_init(struct ifnet *ifp)
 	if (sc->sc_hwinit)
 		(*sc->sc_hwinit)(sc);
 
-
 	/* step 15.  Give the receiver a swift kick */
-	bus_space_write_4(t, h, GEM_RX_KICK, GEM_NRXDESC-4);
+	bus_space_write_4(t, h, GEM_RX_KICK, sc->sc_rx_prod);
 
 	/* Start the one second timer. */
 	timeout_add_sec(&sc->sc_tick_ch, 1);
@@ -931,7 +921,7 @@ gem_rint(struct gem_softc *sc)
 	u_int64_t rxstat;
 	int i, len;
 
-	for (i = sc->sc_rxptr;; i = GEM_NEXTRX(i)) {
+	for (i = sc->sc_rx_cons; sc->sc_rx_cnt > 0; i = GEM_NEXTRX(i)) {
 		rxs = &sc->sc_rxsoft[i];
 
 		GEM_CDRXSYNC(sc, i,
@@ -940,23 +930,29 @@ gem_rint(struct gem_softc *sc)
 		rxstat = GEM_DMA_READ(sc, sc->sc_rxdescs[i].gd_flags);
 
 		if (rxstat & GEM_RD_OWN) {
-			/*
-			 * We have processed all of the receive buffers.
-			 */
+			/* We have processed all of the receive buffers. */
 			break;
 		}
 
+		bus_dmamap_sync(sc->sc_dmatag, rxs->rxs_dmamap, 0,
+		    rxs->rxs_dmamap->dm_mapsize, BUS_DMASYNC_POSTREAD);
+		bus_dmamap_unload(sc->sc_dmatag, rxs->rxs_dmamap);
+
+		m = rxs->rxs_mbuf;
+		rxs->rxs_mbuf = NULL;
+
+		sc->sc_rx_cnt--;
+
 		if (rxstat & GEM_RD_BAD_CRC) {
+			ifp->if_ierrors++;
 #ifdef GEM_DEBUG
 			printf("%s: receive error: CRC error\n",
 				sc->sc_dev.dv_xname);
 #endif
-			GEM_INIT_RXDESC(sc, i);
+			m_freem(m);
 			continue;
 		}
 
-		bus_dmamap_sync(sc->sc_dmatag, rxs->rxs_dmamap, 0,
-		    rxs->rxs_dmamap->dm_mapsize, BUS_DMASYNC_POSTREAD);
 #ifdef GEM_DEBUG
 		if (ifp->if_flags & IFF_DEBUG) {
 			printf("    rxsoft %p descriptor %d: ", rxs, i);
@@ -970,19 +966,6 @@ gem_rint(struct gem_softc *sc)
 		/* No errors; receive the packet. */
 		len = GEM_RD_BUFLEN(rxstat);
 
-		/*
-		 * Allocate a new mbuf cluster.  If that fails, we are
-		 * out of memory, and must drop the packet and recycle
-		 * the buffer that's already attached to this descriptor.
-		 */
-		m = rxs->rxs_mbuf;
-		if (gem_add_rxbuf(sc, i) != 0) {
-			ifp->if_ierrors++;
-			GEM_INIT_RXDESC(sc, i);
-			bus_dmamap_sync(sc->sc_dmatag, rxs->rxs_dmamap, 0,
-			    rxs->rxs_dmamap->dm_mapsize, BUS_DMASYNC_PREREAD);
-			continue;
-		}
 		m->m_data += 2; /* We're already off by two */
 
 		ifp->if_ipackets++;
@@ -990,10 +973,6 @@ gem_rint(struct gem_softc *sc)
 		m->m_pkthdr.len = m->m_len = len;
 
 #if NBPFILTER > 0
-		/*
-		 * Pass this up to any BPF listeners, but only
-		 * pass it up the stack if its for us.
-		 */
 		if (ifp->if_bpf)
 			bpf_mtap(ifp->if_bpf, m, BPF_DIRECTION_IN);
 #endif /* NBPFILTER > 0 */
@@ -1003,15 +982,24 @@ gem_rint(struct gem_softc *sc)
 	}
 
 	/* Update the receive pointer. */
-	sc->sc_rxptr = i;
-	bus_space_write_4(t, h, GEM_RX_KICK, i);
+	sc->sc_rx_cons = i;
+	gem_fill_rx_ring(sc);
+	bus_space_write_4(t, h, GEM_RX_KICK, sc->sc_rx_prod);
 
-	DPRINTF(sc, ("gem_rint: done sc->rxptr %d, complete %d\n",
-		sc->sc_rxptr, bus_space_read_4(t, h, GEM_RX_COMPLETION)));
+	DPRINTF(sc, ("gem_rint: done sc->sc_rx_cons %d, complete %d\n",
+		sc->sc_rx_cons, bus_space_read_4(t, h, GEM_RX_COMPLETION)));
 
 	return (1);
 }
 
+void
+gem_fill_rx_ring(struct gem_softc *sc)
+{
+	while (sc->sc_rx_cnt < (GEM_NRXDESC - 4)) {
+		if (gem_add_rxbuf(sc, sc->sc_rx_prod))
+			break;
+	}
+}
 
 /*
  * Add a receive buffer to the indicated descriptor.
@@ -1027,24 +1015,21 @@ gem_add_rxbuf(struct gem_softc *sc, int idx)
 	if (m == NULL)
 		return (ENOBUFS);
 
-	MCLGET(m, M_DONTWAIT);
+	MCLGETI(m, M_DONTWAIT, &sc->sc_arpcom.ac_if, MCLBYTES);
 	if ((m->m_flags & M_EXT) == 0) {
 		m_freem(m);
 		return (ENOBUFS);
 	}
+	m->m_len = m->m_pkthdr.len = MCLBYTES;
 
 #ifdef GEM_DEBUG
 /* bzero the packet to check dma */
 	memset(m->m_ext.ext_buf, 0, m->m_ext.ext_size);
 #endif
 
-	if (rxs->rxs_mbuf != NULL)
-		bus_dmamap_unload(sc->sc_dmatag, rxs->rxs_dmamap);
-
 	rxs->rxs_mbuf = m;
 
-	error = bus_dmamap_load(sc->sc_dmatag, rxs->rxs_dmamap,
-	    m->m_ext.ext_buf, m->m_ext.ext_size, NULL,
+	error = bus_dmamap_load_mbuf(sc->sc_dmatag, rxs->rxs_dmamap, m,
 	    BUS_DMA_READ|BUS_DMA_NOWAIT);
 	if (error) {
 		printf("%s: can't load rx DMA map %d, error = %d\n",
@@ -1057,6 +1042,9 @@ gem_add_rxbuf(struct gem_softc *sc, int idx)
 
 	GEM_INIT_RXDESC(sc, idx);
 
+	sc->sc_rx_prod = GEM_NEXTRX(sc->sc_rx_prod);
+	sc->sc_rx_cnt++;
+
 	return (0);
 }
 
@@ -1135,14 +1123,8 @@ gem_intr(void *v)
  			printf("%s: MAC rx fault, status %x\n",
  			    sc->sc_dev.dv_xname, rxstat);
 #endif
-		/*
-		 * On some chip revisions GEM_MAC_RX_OVERFLOW happen often
-		 * due to a silicon bug so handle them silently.
-		 */
-		if (rxstat & GEM_MAC_RX_OVERFLOW) {
+		if (rxstat & GEM_MAC_RX_OVERFLOW)
 			ifp->if_ierrors++;
-			gem_init(ifp);
-		}
 #ifdef GEM_DEBUG
 		else if (rxstat & ~(GEM_MAC_RX_DONE | GEM_MAC_RX_FRAME_CNT))
 			printf("%s: MAC rx fault, status %x\n",
diff --git a/sys/dev/ic/gemvar.h b/sys/dev/ic/gemvar.h
index cf394795928..1abe2ce3cfa 100644
--- a/sys/dev/ic/gemvar.h
+++ b/sys/dev/ic/gemvar.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: gemvar.h,v 1.19 2008/11/07 18:03:52 brad Exp $	*/
+/*	$OpenBSD: gemvar.h,v 1.20 2008/12/14 21:31:50 kettenis Exp $	*/
 /*	$NetBSD: gemvar.h,v 1.1 2001/09/16 00:11:43 eeh Exp $ */
 
 /*
@@ -175,6 +175,7 @@ struct gem_softc {
 	u_int32_t sc_tx_cnt, sc_tx_prod, sc_tx_cons;
 
 	struct gem_rxsoft sc_rxsoft[GEM_NRXDESC];
+	u_int32_t sc_rx_cnt, sc_rx_prod, sc_rx_cons;
 
 	/*
 	 * Control data structures.
@@ -191,7 +192,6 @@ struct gem_softc {
 
 	u_int32_t		sc_setup_fsls;	/* FS|LS on setup descriptor */
 
-	int			sc_rxptr;		/* next ready RX descriptor/descsoft */
 	int			sc_rxfifosize;
 
 	/* ========== */
@@ -262,7 +262,6 @@ do {									\
 	struct gem_desc *__rxd = &sc->sc_rxdescs[(x)];			\
 	struct mbuf *__m = __rxs->rxs_mbuf;				\
 									\
-	__m->m_data = __m->m_ext.ext_buf;				\
 	__rxd->gd_addr =						\
 	    GEM_DMA_WRITE((sc), __rxs->rxs_dmamap->dm_segs[0].ds_addr);	\
 	__rxd->gd_flags =						\