- Make use of m_defrag().

- Lower the max # of TX DMA segments from close to the whole ring down
  to a more sensible value. From FreeBSD
- Move the TX ring full check out of and above the for loop.
- Use dm_nsegs to provide the total # of DMA segments instead of the
  value from the for loop.

ok mikeb@

2 files changed, 28 insertions, 10 deletions

diff --git a/sys/dev/pci/if_sis.c b/sys/dev/pci/if_sis.c
index e1991124338..8e1b70d84ad 100644
--- a/sys/dev/pci/if_sis.c
+++ b/sys/dev/pci/if_sis.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_sis.c,v 1.122 2015/01/06 04:05:43 brad Exp $ */
+/*	$OpenBSD: if_sis.c,v 1.123 2015/02/11 21:36:02 brad Exp $ */
 /*
  * Copyright (c) 1997, 1998, 1999
  *	Bill Paul <wpaul@ctr.columbia.edu>.  All rights reserved.
@@ -1168,13 +1168,13 @@ sis_attach(struct device *parent, struct device *self, void *aux)
 
 	for (i = 0; i < SIS_TX_LIST_CNT; i++) {
 		if (bus_dmamap_create(sc->sc_dmat, MCLBYTES,
-		    SIS_TX_LIST_CNT - 3, MCLBYTES, 0, BUS_DMA_NOWAIT,
+		    SIS_MAXTXSEGS, MCLBYTES, 0, BUS_DMA_NOWAIT,
 		    &sc->sis_ldata->sis_tx_list[i].map) != 0) {
 			printf(": can't create tx map\n");
 			goto fail_2;
 		}
 	}
-	if (bus_dmamap_create(sc->sc_dmat, MCLBYTES, SIS_TX_LIST_CNT - 3,
+	if (bus_dmamap_create(sc->sc_dmat, MCLBYTES, SIS_MAXTXSEGS,
 	    MCLBYTES, 0, BUS_DMA_NOWAIT, &sc->sc_tx_sparemap) != 0) {
 		printf(": can't create tx spare map\n");
 		goto fail_2;
@@ -1598,13 +1598,32 @@ int
 sis_encap(struct sis_softc *sc, struct mbuf *m_head, u_int32_t *txidx)
 {
 	struct sis_desc		*f = NULL;
-	int			frag, cur, i;
 	bus_dmamap_t		map;
+	int			frag, cur, i, error;
 
 	map = sc->sc_tx_sparemap;
-	if (bus_dmamap_load_mbuf(sc->sc_dmat, map,
-	    m_head, BUS_DMA_NOWAIT) != 0)
+
+	error = bus_dmamap_load_mbuf(sc->sc_dmat, map, m_head,
+	    BUS_DMA_NOWAIT);
+	switch (error) {
+	case 0:
+		break;
+
+	case EFBIG:
+		if (m_defrag(m_head, M_DONTWAIT) == 0 &&
+		    bus_dmamap_load_mbuf(sc->sc_dmat, map, m_head,
+		    BUS_DMA_NOWAIT) == 0)
+			break;
+
+		/* FALLTHROUGH */
+	default:
 		return (ENOBUFS);
+	}
+
+	if ((SIS_TX_LIST_CNT - (sc->sis_cdata.sis_tx_cnt + map->dm_nsegs)) < 2) {
+		bus_dmamap_unload(sc->sc_dmat, map);
+		return (ENOBUFS);
+	}
 
 	/*
  	 * Start packing the mbufs in this chain into
@@ -1614,8 +1633,6 @@ sis_encap(struct sis_softc *sc, struct mbuf *m_head, u_int32_t *txidx)
 	cur = frag = *txidx;
 
 	for (i = 0; i < map->dm_nsegs; i++) {
-		if ((SIS_TX_LIST_CNT - (sc->sis_cdata.sis_tx_cnt + i)) < 2)
-			return(ENOBUFS);
 		f = &sc->sis_ldata->sis_tx_list[frag];
 		f->sis_ctl = htole32(SIS_CMDSTS_MORE | map->dm_segs[i].ds_len);
 		f->sis_ptr = htole32(map->dm_segs[i].ds_addr);
@@ -1631,7 +1648,7 @@ sis_encap(struct sis_softc *sc, struct mbuf *m_head, u_int32_t *txidx)
 	sc->sis_ldata->sis_tx_list[cur].sis_mbuf = m_head;
 	sc->sis_ldata->sis_tx_list[cur].sis_ctl &= ~htole32(SIS_CMDSTS_MORE);
 	sc->sis_ldata->sis_tx_list[*txidx].sis_ctl |= htole32(SIS_CMDSTS_OWN);
-	sc->sis_cdata.sis_tx_cnt += i;
+	sc->sis_cdata.sis_tx_cnt += map->dm_nsegs;
 	*txidx = frag;
 
 	bus_dmamap_sync(sc->sc_dmat, sc->sc_listmap,
diff --git a/sys/dev/pci/if_sisreg.h b/sys/dev/pci/if_sisreg.h
index 6e54e88634f..9d9074e28fe 100644
--- a/sys/dev/pci/if_sisreg.h
+++ b/sys/dev/pci/if_sisreg.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_sisreg.h,v 1.33 2014/07/08 05:35:18 dlg Exp $ */
+/*	$OpenBSD: if_sisreg.h,v 1.34 2015/02/11 21:36:02 brad Exp $ */
 /*
  * Copyright (c) 1997, 1998, 1999
  *	Bill Paul <wpaul@ee.columbia.edu>.  All rights reserved.
@@ -376,6 +376,7 @@ struct sis_desc {
 #define SIS_TXSTAT_UNDERRUN	0x02000000
 #define SIS_TXSTAT_TX_ABORT	0x04000000
 
+#define SIS_MAXTXSEGS		16
 #define SIS_RX_LIST_CNT		64
 #define SIS_TX_LIST_CNT		128