nfp: forbid disabling hw-tc-offload on representors while offload active

All netdevs which can accept TC offloads must implement
.ndo_set_features().  nfp_reprs currently do not do that, which
means hw-tc-offload can be turned on and off even when offloads
are active.

Whether the offloads are active is really a question to nfp_ports,
so remove the per-app tc_busy callback indirection thing, and
simply count the number of offloaded items in nfp_port structure.

Fixes: 8a2768732a4d ("nfp: provide infrastructure for offloading flower based TC filters")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Tested-by: Pieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/bpf/main.c

@@ -182,6 +182,7 @@ static int nfp_bpf_setup_tc_block_cb(enum tc_setup_type type,
 		return err;
 
 	bv->tc_prog = cls_bpf->prog;
+	nn->port->tc_offload_cnt = !!bv->tc_prog;
 	return 0;
 }
 
@@ -219,13 +220,6 @@ static int nfp_bpf_setup_tc(struct nfp_app *app, struct net_device *netdev,
 	}
 }
 
-static bool nfp_bpf_tc_busy(struct nfp_app *app, struct nfp_net *nn)
-{
-	struct nfp_bpf_vnic *bv = nn->app_priv;
-
-	return !!bv->tc_prog;
-}
-
 static int
 nfp_bpf_change_mtu(struct nfp_app *app, struct net_device *netdev, int new_mtu)
 {
@@ -429,7 +423,6 @@ const struct nfp_app_type app_bpf = {
 	.ctrl_msg_rx	= nfp_bpf_ctrl_msg_rx,
 
 	.setup_tc	= nfp_bpf_setup_tc,
-	.tc_busy	= nfp_bpf_tc_busy,
 	.bpf		= nfp_ndo_bpf,
 	.xdp_offload	= nfp_bpf_xdp_offload,
 };

drivers/net/ethernet/netronome/nfp/flower/offload.c

@@ -349,6 +349,7 @@ nfp_flower_add_offload(struct nfp_app *app, struct net_device *netdev,
 		       struct tc_cls_flower_offload *flow, bool egress)
 {
 	enum nfp_flower_tun_type tun_type = NFP_FL_TUNNEL_NONE;
+	struct nfp_port *port = nfp_port_from_netdev(netdev);
 	struct nfp_flower_priv *priv = app->priv;
 	struct nfp_fl_payload *flow_pay;
 	struct nfp_fl_key_ls *key_layer;
@@ -390,6 +391,7 @@ nfp_flower_add_offload(struct nfp_app *app, struct net_device *netdev,
 	INIT_HLIST_NODE(&flow_pay->link);
 	flow_pay->tc_flower_cookie = flow->cookie;
 	hash_add_rcu(priv->flow_table, &flow_pay->link, flow->cookie);
+	port->tc_offload_cnt++;
 
 	/* Deallocate flow payload when flower rule has been destroyed. */
 	kfree(key_layer);
@@ -421,6 +423,7 @@ static int
 nfp_flower_del_offload(struct nfp_app *app, struct net_device *netdev,
 		       struct tc_cls_flower_offload *flow)
 {
+	struct nfp_port *port = nfp_port_from_netdev(netdev);
 	struct nfp_fl_payload *nfp_flow;
 	int err;
 
@@ -442,6 +445,7 @@ nfp_flower_del_offload(struct nfp_app *app, struct net_device *netdev,
 
 err_free_flow:
 	hash_del_rcu(&nfp_flow->link);
+	port->tc_offload_cnt--;
 	kfree(nfp_flow->action_data);
 	kfree(nfp_flow->mask_data);
 	kfree(nfp_flow->unmasked_data);

drivers/net/ethernet/netronome/nfp/nfp_app.h

@@ -92,7 +92,6 @@ extern const struct nfp_app_type app_flower;
  * @stop:	stop application logic
  * @ctrl_msg_rx:    control message handler
  * @setup_tc:	setup TC ndo
- * @tc_busy:	TC HW offload busy (rules loaded)
  * @bpf:	BPF ndo offload-related calls
  * @xdp_offload:    offload an XDP program
  * @eswitch_mode_get:    get SR-IOV eswitch mode
@@ -135,7 +134,6 @@ struct nfp_app_type {
 
 	int (*setup_tc)(struct nfp_app *app, struct net_device *netdev,
 			enum tc_setup_type type, void *type_data);
-	bool (*tc_busy)(struct nfp_app *app, struct nfp_net *nn);
 	int (*bpf)(struct nfp_app *app, struct nfp_net *nn,
 		   struct netdev_bpf *xdp);
 	int (*xdp_offload)(struct nfp_app *app, struct nfp_net *nn,
@@ -301,13 +299,6 @@ static inline bool nfp_app_has_tc(struct nfp_app *app)
 	return app && app->type->setup_tc;
 }
 
-static inline bool nfp_app_tc_busy(struct nfp_app *app, struct nfp_net *nn)
-{
-	if (!app || !app->type->tc_busy)
-		return false;
-	return app->type->tc_busy(app, nn);
-}
-
 static inline int nfp_app_setup_tc(struct nfp_app *app,
 				   struct net_device *netdev,
 				   enum tc_setup_type type, void *type_data)

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

@@ -3210,10 +3210,9 @@ static int nfp_net_set_features(struct net_device *netdev,
 			new_ctrl &= ~NFP_NET_CFG_CTRL_GATHER;
 	}
 
-	if (changed & NETIF_F_HW_TC && nfp_app_tc_busy(nn->app, nn)) {
-		nn_err(nn, "Cannot disable HW TC offload while in use\n");
-		return -EBUSY;
-	}
+	err = nfp_port_set_features(netdev, features);
+	if (err)
+		return err;
 
 	nn_dbg(nn, "Feature change 0x%llx -> 0x%llx (changed=0x%llx)\n",
 	       netdev->features, features, changed);

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

@@ -265,6 +265,7 @@ const struct net_device_ops nfp_repr_netdev_ops = {
 	.ndo_set_vf_spoofchk	= nfp_app_set_vf_spoofchk,
 	.ndo_get_vf_config	= nfp_app_get_vf_config,
 	.ndo_set_vf_link_state	= nfp_app_set_vf_link_state,
+	.ndo_set_features	= nfp_port_set_features,
 };
 
 static void nfp_repr_clean(struct nfp_repr *repr)

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

@@ -32,6 +32,7 @@
  */
 
 #include <linux/lockdep.h>
+#include <linux/netdevice.h>
 #include <net/switchdev.h>
 
 #include "nfpcore/nfp_cpp.h"
@@ -100,6 +101,23 @@ int nfp_port_setup_tc(struct net_device *netdev, enum tc_setup_type type,
 	return nfp_app_setup_tc(port->app, netdev, type, type_data);
 }
 
+int nfp_port_set_features(struct net_device *netdev, netdev_features_t features)
+{
+	struct nfp_port *port;
+
+	port = nfp_port_from_netdev(netdev);
+	if (!port)
+		return 0;
+
+	if ((netdev->features & NETIF_F_HW_TC) > (features & NETIF_F_HW_TC) &&
+	    port->tc_offload_cnt) {
+		netdev_err(netdev, "Cannot disable HW TC offload while offloads active\n");
+		return -EBUSY;
+	}
+
+	return 0;
+}
+
 struct nfp_port *
 nfp_port_from_id(struct nfp_pf *pf, enum nfp_port_type type, unsigned int id)
 {

drivers/net/ethernet/netronome/nfp/nfp_port.h

@@ -72,6 +72,8 @@ enum nfp_port_flags {
  * @netdev:	backpointer to associated netdev
  * @type:	what port type does the entity represent
  * @flags:	port flags
+ * @tc_offload_cnt:	number of active TC offloads, how offloads are counted
+ *			is not defined, use as a boolean
  * @app:	backpointer to the app structure
  * @dl_port:	devlink port structure
  * @eth_id:	for %NFP_PORT_PHYS_PORT port ID in NFP enumeration scheme
@@ -87,6 +89,7 @@ struct nfp_port {
 	enum nfp_port_type type;
 
 	unsigned long flags;
+	unsigned long tc_offload_cnt;
 
 	struct nfp_app *app;
 
@@ -121,6 +124,9 @@ static inline bool nfp_port_is_vnic(const struct nfp_port *port)
 	return port->type == NFP_PORT_PF_PORT || port->type == NFP_PORT_VF_PORT;
 }
 
+int
+nfp_port_set_features(struct net_device *netdev, netdev_features_t features);
+
 struct nfp_port *nfp_port_from_netdev(struct net_device *netdev);
 struct nfp_port *
 nfp_port_from_id(struct nfp_pf *pf, enum nfp_port_type type, unsigned int id);