netmap: iflib: add nm_config callback

This per-driver callback is invoked by netmap when it wants
to align the number of TX/RX netmap rings and/or the number of
TX/RX netmap slots to the actual state configured in the hardware.
The alignment happens when netmap mode is switched on (with no
active netmap file descriptors for that netmap port), or when
collecting netmap port information.

MFC after:	1 week

sys/net/iflib.c

@@ -829,6 +829,26 @@ iflib_netmap_register(struct netmap_adapter *na, int onoff)
 	return (status);
 }
 
+static int
+iflib_netmap_config(struct netmap_adapter *na, struct nm_config_info *info)
+{
+	if_t ifp = na->ifp;
+	if_ctx_t ctx = ifp->if_softc;
+	iflib_rxq_t rxq = &ctx->ifc_rxqs[0];
+	iflib_fl_t fl = &rxq->ifr_fl[0];
+
+	info->num_tx_rings = ctx->ifc_softc_ctx.isc_ntxqsets;
+	info->num_rx_rings = ctx->ifc_softc_ctx.isc_nrxqsets;
+	info->num_tx_descs = iflib_num_tx_descs(ctx);
+	info->num_rx_descs = iflib_num_rx_descs(ctx);
+	info->rx_buf_maxsize = fl->ifl_buf_size;
+	nm_prinf("txr %u rxr %u txd %u rxd %u rbufsz %u",
+		info->num_tx_rings, info->num_rx_rings, info->num_tx_descs,
+		info->num_rx_descs, info->rx_buf_maxsize);
+
+	return 0;
+}
+
 static int
 netmap_fl_refill(iflib_rxq_t rxq, struct netmap_kring *kring, bool init)
 {
@@ -1279,6 +1299,7 @@ iflib_netmap_attach(if_ctx_t ctx)
 	na.nm_rxsync = iflib_netmap_rxsync;
 	na.nm_register = iflib_netmap_register;
 	na.nm_intr = iflib_netmap_intr;
+	na.nm_config = iflib_netmap_config;
 	na.num_tx_rings = ctx->ifc_softc_ctx.isc_ntxqsets;
 	na.num_rx_rings = ctx->ifc_softc_ctx.isc_nrxqsets;
 	return (netmap_attach(&na));