nfp: implement netpoll ndo (thus enabling netconsole)

NFP NAPI handling will only complete the TXed packets when called
with budget of 0, implement ndo_poll_controller by scheduling NAPI
on all TX queues.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/nfp_net_common.c

@@ -3115,6 +3115,21 @@ nfp_net_vlan_rx_kill_vid(struct net_device *netdev, __be16 proto, u16 vid)
 	return nfp_net_reconfig_mbox(nn, NFP_NET_CFG_MBOX_CMD_CTAG_FILTER_KILL);
 }
 
+#ifdef CONFIG_NET_POLL_CONTROLLER
+static void nfp_net_netpoll(struct net_device *netdev)
+{
+	struct nfp_net *nn = netdev_priv(netdev);
+	int i;
+
+	/* nfp_net's NAPIs are statically allocated so even if there is a race
+	 * with reconfig path this will simply try to schedule some disabled
+	 * NAPI instances.
+	 */
+	for (i = 0; i < nn->dp.num_stack_tx_rings; i++)
+		napi_schedule_irqoff(&nn->r_vecs[i].napi);
+}
+#endif
+
 static void nfp_net_stat64(struct net_device *netdev,
 			   struct rtnl_link_stats64 *stats)
 {
@@ -3482,6 +3497,9 @@ const struct net_device_ops nfp_net_netdev_ops = {
 	.ndo_get_stats64	= nfp_net_stat64,
 	.ndo_vlan_rx_add_vid	= nfp_net_vlan_rx_add_vid,
 	.ndo_vlan_rx_kill_vid	= nfp_net_vlan_rx_kill_vid,
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	.ndo_poll_controller	= nfp_net_netpoll,
+#endif
 	.ndo_set_vf_mac         = nfp_app_set_vf_mac,
 	.ndo_set_vf_vlan        = nfp_app_set_vf_vlan,
 	.ndo_set_vf_spoofchk    = nfp_app_set_vf_spoofchk,