Fix the panic recently reported on -current@ occuring when configuring

a vlan interface attached to a fxp(4) card when it has not been
initialized yet.  We now set the links from our internel TX descriptor
structure to the TX command blocks at attach time rather than at init
time.  While I'm here, slightly improve the style in fxp_attach().

PR:		kern/78112
Reported by:	Gavin Atkinson <gavin.atkinson@ury.york.ac.uk> and others
Tested by:	flz, Gavin Atkinson <gavin.atkinson@ury.york.ac.uk>
MFC after:	1 week

1 files changed, 13 insertions, 8 deletions

diff --git a/sys/dev/fxp/if_fxp.c b/sys/dev/fxp/if_fxp.c
index 644ec2c..9b003f8 100644
--- a/sys/dev/fxp/if_fxp.c
+++ b/sys/dev/fxp/if_fxp.c
@@ -364,15 +364,18 @@ fxp_dma_map_addr(void *arg, bus_dma_segment_t *segs, int nseg, int error)
 static int
 fxp_attach(device_t dev)
 {
-	int error = 0;
-	struct fxp_softc *sc = device_get_softc(dev);
-	struct ifnet *ifp;
+	struct fxp_softc *sc;
+	struct fxp_cb_tx *tcbp;
+	struct fxp_tx *txp;
 	struct fxp_rx *rxp;
+	struct ifnet *ifp;
 	u_int32_t val;
 	u_int16_t data, myea[ETHER_ADDR_LEN / 2];
 	int i, rid, m1, m2, prefer_iomap, maxtxseg;
-	int s;
+	int error, s;
 
+	error = 0;
+	sc = device_get_softc(dev);
 	sc->dev = dev;
 	callout_init(&sc->stat_ch, CALLOUT_MPSAFE);
 	mtx_init(&sc->sc_mtx, device_get_nameunit(dev), MTX_NETWORK_LOCK,
@@ -658,11 +661,14 @@ fxp_attach(device_t dev)
 	}
 
 	/*
-	 * Pre-allocate the TX DMA maps.
+	 * Pre-allocate the TX DMA maps and setup the pointers to
+	 * the TX command blocks.
 	 */
+	txp = sc->fxp_desc.tx_list;
+	tcbp = sc->fxp_desc.cbl_list;
 	for (i = 0; i < FXP_NTXCB; i++) {
-		error = bus_dmamap_create(sc->fxp_mtag, 0,
-		    &sc->fxp_desc.tx_list[i].tx_map);
+		txp[i].tx_cb = tcbp + i;
+		error = bus_dmamap_create(sc->fxp_mtag, 0, &txp[i].tx_map);
 		if (error) {
 			device_printf(dev, "can't create DMA map for TX\n");
 			goto fail;
@@ -2132,7 +2138,6 @@ fxp_init_body(struct fxp_softc *sc)
 	tcbp = sc->fxp_desc.cbl_list;
 	bzero(tcbp, FXP_TXCB_SZ);
 	for (i = 0; i < FXP_NTXCB; i++) {
-		txp[i].tx_cb = tcbp + i;
 		txp[i].tx_mbuf = NULL;
 		tcbp[i].cb_status = htole16(FXP_CB_STATUS_C | FXP_CB_STATUS_OK);
 		tcbp[i].cb_command = htole16(FXP_CB_COMMAND_NOP);