net: dsa: tag_ocelot: convert to tagger-owned data

The felix driver makes very light use of dp->priv, and the tagger is
effectively stateless. dp->priv is practically only needed to set up a
callback to perform deferred xmit of PTP and STP packets using the
ocelot-8021q tagging protocol (the main ocelot tagging protocol makes no
use of dp->priv, although this driver sets up dp->priv irrespective of
actual tagging protocol in use).

struct felix_port (what used to be pointed to by dp->priv) is removed
and replaced with a two-sided structure. The public side of this
structure, visible to the switch driver, is ocelot_8021q_tagger_data.
The private side is ocelot_8021q_tagger_private, and the latter
structure physically encapsulates the former. The public half of the
tagger data structure can be accessed through a helper of the same name
(ocelot_8021q_tagger_data) which also sanity-checks the protocol
currently in use by the switch. The public/private split was requested
by Andrew Lunn.

Suggested-by: Andrew Lunn <[e-mail]>
Signed-off-by: Vladimir Oltean <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/dsa/ocelot/felix.c

···
 	kfree(xmit_work);
 }
 
-static int felix_port_setup_tagger_data(struct dsa_switch *ds, int port)
+static int felix_connect_tag_protocol(struct dsa_switch *ds,
+				      enum dsa_tag_protocol proto)
 {
-	struct dsa_port *dp = dsa_to_port(ds, port);
-	struct ocelot *ocelot = ds->priv;
-	struct felix *felix = ocelot_to_felix(ocelot);
-	struct felix_port *felix_port;
+	struct ocelot_8021q_tagger_data *tagger_data;
 
-	if (!dsa_port_is_user(dp))
+	switch (proto) {
+	case DSA_TAG_PROTO_OCELOT_8021Q:
+		tagger_data = ocelot_8021q_tagger_data(ds);
+		tagger_data->xmit_work_fn = felix_port_deferred_xmit;
 		return 0;
-
-	felix_port = kzalloc(sizeof(*felix_port), GFP_KERNEL);
-	if (!felix_port)
-		return -ENOMEM;
-
-	felix_port->xmit_worker = felix->xmit_worker;
-	felix_port->xmit_work_fn = felix_port_deferred_xmit;
-
-	dp->priv = felix_port;
-
-	return 0;
-}
-
-static void felix_port_teardown_tagger_data(struct dsa_switch *ds, int port)
-{
-	struct dsa_port *dp = dsa_to_port(ds, port);
-	struct felix_port *felix_port = dp->priv;
-
-	if (!felix_port)
-		return;
-
-	dp->priv = NULL;
-	kfree(felix_port);
+	case DSA_TAG_PROTO_OCELOT:
+	case DSA_TAG_PROTO_SEVILLE:
+		return 0;
+	default:
+		return -EPROTONOSUPPORT;
+	}
 }
 
 /* Hardware initialization done here so that we can allocate structures with
···
 		}
 	}
 
-	felix->xmit_worker = kthread_create_worker(0, "felix_xmit");
-	if (IS_ERR(felix->xmit_worker)) {
-		err = PTR_ERR(felix->xmit_worker);
-		goto out_deinit_timestamp;
-	}
-
 	for (port = 0; port < ds->num_ports; port++) {
 		if (dsa_is_unused_port(ds, port))
 			continue;
···
 		 * bits of vlan tag.
 		 */
 		felix_port_qos_map_init(ocelot, port);
-
-		err = felix_port_setup_tagger_data(ds, port);
-		if (err) {
-			dev_err(ds->dev,
-				"port %d failed to set up tagger data: %pe\n",
-				port, ERR_PTR(err));
-			goto out_deinit_ports;
-		}
 	}
 
 	err = ocelot_devlink_sb_register(ocelot);
···
 		if (dsa_is_unused_port(ds, port))
 			continue;
 
-		felix_port_teardown_tagger_data(ds, port);
 		ocelot_deinit_port(ocelot, port);
 	}
 
-	kthread_destroy_worker(felix->xmit_worker);
-
-out_deinit_timestamp:
 	ocelot_deinit_timestamp(ocelot);
 	ocelot_deinit(ocelot);
 
···
 		if (dsa_is_unused_port(ds, port))
 			continue;
 
-		felix_port_teardown_tagger_data(ds, port);
 		ocelot_deinit_port(ocelot, port);
 	}
-
-	kthread_destroy_worker(felix->xmit_worker);
 
 	ocelot_devlink_sb_unregister(ocelot);
 	ocelot_deinit_timestamp(ocelot);
···
 const struct dsa_switch_ops felix_switch_ops = {
 	.get_tag_protocol		= felix_get_tag_protocol,
 	.change_tag_protocol		= felix_change_tag_protocol,
+	.connect_tag_protocol		= felix_connect_tag_protocol,
 	.setup				= felix_setup,
 	.teardown			= felix_teardown,
 	.set_ageing_time		= felix_set_ageing_time,

include/linux/dsa/ocelot.h

···
 #include <linux/kthread.h>
 #include <linux/packing.h>
 #include <linux/skbuff.h>
+#include <net/dsa.h>
 
 struct ocelot_skb_cb {
 	struct sk_buff *clone;
···
 	struct kthread_work work;
 };
 
-struct felix_port {
+struct ocelot_8021q_tagger_data {
 	void (*xmit_work_fn)(struct kthread_work *work);
-	struct kthread_worker *xmit_worker;
 };
+
+static inline struct ocelot_8021q_tagger_data *
+ocelot_8021q_tagger_data(struct dsa_switch *ds)
+{
+	BUG_ON(ds->dst->tag_ops->proto != DSA_TAG_PROTO_OCELOT_8021Q);
+
+	return ds->tagger_data;
+}
 
 static inline void ocelot_xfh_get_rew_val(void *extraction, u64 *rew_val)
 {

net/dsa/tag_ocelot_8021q.c

···
 #include <linux/dsa/ocelot.h>
 #include "dsa_priv.h"
 
+struct ocelot_8021q_tagger_private {
+	struct ocelot_8021q_tagger_data data; /* Must be first */
+	struct kthread_worker *xmit_worker;
+};
+
 static struct sk_buff *ocelot_defer_xmit(struct dsa_port *dp,
 					 struct sk_buff *skb)
 {
+	struct ocelot_8021q_tagger_private *priv = dp->ds->tagger_data;
+	struct ocelot_8021q_tagger_data *data = &priv->data;
+	void (*xmit_work_fn)(struct kthread_work *work);
 	struct felix_deferred_xmit_work *xmit_work;
-	struct felix_port *felix_port = dp->priv;
+	struct kthread_worker *xmit_worker;
+
+	xmit_work_fn = data->xmit_work_fn;
+	xmit_worker = priv->xmit_worker;
+
+	if (!xmit_work_fn || !xmit_worker)
+		return NULL;
 
 	xmit_work = kzalloc(sizeof(*xmit_work), GFP_ATOMIC);
 	if (!xmit_work)
 		return NULL;
 
 	/* Calls felix_port_deferred_xmit in felix.c */
-	kthread_init_work(&xmit_work->work, felix_port->xmit_work_fn);
+	kthread_init_work(&xmit_work->work, xmit_work_fn);
 	/* Increase refcount so the kfree_skb in dsa_slave_xmit
 	 * won't really free the packet.
 	 */
 	xmit_work->dp = dp;
 	xmit_work->skb = skb_get(skb);
 
-	kthread_queue_work(felix_port->xmit_worker, &xmit_work->work);
+	kthread_queue_work(xmit_worker, &xmit_work->work);
 
 	return NULL;
 }
···
 	return skb;
 }
 
+static void ocelot_disconnect(struct dsa_switch_tree *dst)
+{
+	struct ocelot_8021q_tagger_private *priv;
+	struct dsa_port *dp;
+
+	list_for_each_entry(dp, &dst->ports, list) {
+		priv = dp->ds->tagger_data;
+
+		if (!priv)
+			continue;
+
+		if (priv->xmit_worker)
+			kthread_destroy_worker(priv->xmit_worker);
+
+		kfree(priv);
+		dp->ds->tagger_data = NULL;
+	}
+}
+
+static int ocelot_connect(struct dsa_switch_tree *dst)
+{
+	struct ocelot_8021q_tagger_private *priv;
+	struct dsa_port *dp;
+	int err;
+
+	list_for_each_entry(dp, &dst->ports, list) {
+		if (dp->ds->tagger_data)
+			continue;
+
+		priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+		if (!priv) {
+			err = -ENOMEM;
+			goto out;
+		}
+
+		priv->xmit_worker = kthread_create_worker(0, "felix_xmit");
+		if (IS_ERR(priv->xmit_worker)) {
+			err = PTR_ERR(priv->xmit_worker);
+			goto out;
+		}
+
+		dp->ds->tagger_data = priv;
+	}
+
+	return 0;
+
+out:
+	ocelot_disconnect(dst);
+	return err;
+}
+
 static const struct dsa_device_ops ocelot_8021q_netdev_ops = {
 	.name			= "ocelot-8021q",
 	.proto			= DSA_TAG_PROTO_OCELOT_8021Q,
 	.xmit			= ocelot_xmit,
 	.rcv			= ocelot_rcv,
+	.connect		= ocelot_connect,
+	.disconnect		= ocelot_disconnect,
 	.needed_headroom	= VLAN_HLEN,
 	.promisc_on_master	= true,
 };