Merge branch 'Generic-adjustment-for-flow-dissector-in-DSA'

Vladimir Oltean says:

====================
Generic adjustment for flow dissector in DSA

This is the v2 of a series initially submitted in May:
https://www.spinics.net/lists/netdev/msg651866.html

The end goal is to get rid of the unintuitive code for the flow
dissector that currently exists in the taggers. It can all be replaced
by a single, common function.

Some background work needs to be done for that. Especially the ocelot
driver poses some problems, since it has a different tag length between
RX and TX, and I didn't want to make DSA aware of that, since I could
instead make the tag lengths equal.

Changes in v3:
- Added an optimization (08/15) that makes the generic case not need to
  call the .flow_dissect function pointer. Basically .flow_dissect now
  currently only exists for sja1105.
- Moved the .promisc_on_master property to the tagger structure.
- Added the .tail_tag property to the tagger structure.
- Disabled "suppresscc = all" from my .gitconfig.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 36 insertions, 5 deletions

diff --git a/include/net/dsa.h b/include/net/dsa.h
index d16057c5987a..b502a63d196e 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -74,8 +74,8 @@ struct dsa_device_ops {
 	struct sk_buff *(*xmit)(struct sk_buff *skb, struct net_device *dev);
 	struct sk_buff *(*rcv)(struct sk_buff *skb, struct net_device *dev,
 			       struct packet_type *pt);
-	int (*flow_dissect)(const struct sk_buff *skb, __be16 *proto,
-			    int *offset);
+	void (*flow_dissect)(const struct sk_buff *skb, __be16 *proto,
+			     int *offset);
 	/* Used to determine which traffic should match the DSA filter in
 	 * eth_type_trans, and which, if any, should bypass it and be processed
 	 * as regular on the master net device.
@@ -84,6 +84,13 @@ struct dsa_device_ops {
 	unsigned int overhead;
 	const char *name;
 	enum dsa_tag_protocol proto;
+	/* Some tagging protocols either mangle or shift the destination MAC
+	 * address, in which case the DSA master would drop packets on ingress
+	 * if what it understands out of the destination MAC address is not in
+	 * its RX filter.
+	 */
+	bool promisc_on_master;
+	bool tail_tag;
 };
 
 /* This structure defines the control interfaces that are overlayed by the
@@ -705,6 +712,32 @@ static inline bool dsa_can_decode(const struct sk_buff *skb,
 	return false;
 }
 
+/* All DSA tags that push the EtherType to the right (basically all except tail
+ * tags, which don't break dissection) can be treated the same from the
+ * perspective of the flow dissector.
+ *
+ * We need to return:
+ *  - offset: the (B - A) difference between:
+ *    A. the position of the real EtherType and
+ *    B. the current skb->data (aka ETH_HLEN bytes into the frame, aka 2 bytes
+ *       after the normal EtherType was supposed to be)
+ *    The offset in bytes is exactly equal to the tagger overhead (and half of
+ *    that, in __be16 shorts).
+ *
+ *  - proto: the value of the real EtherType.
+ */
+static inline void dsa_tag_generic_flow_dissect(const struct sk_buff *skb,
+						__be16 *proto, int *offset)
+{
+#if IS_ENABLED(CONFIG_NET_DSA)
+	const struct dsa_device_ops *ops = skb->dev->dsa_ptr->tag_ops;
+	int tag_len = ops->overhead;
+
+	*offset = tag_len;
+	*proto = ((__be16 *)skb->data)[(tag_len / 2) - 1];
+#endif
+}
+
 #if IS_ENABLED(CONFIG_NET_DSA)
 static inline int __dsa_netdevice_ops_check(struct net_device *dev)
 {
diff --git a/include/soc/mscc/ocelot.h b/include/soc/mscc/ocelot.h
index 3105bbb6cdcf..3093385f6147 100644
--- a/include/soc/mscc/ocelot.h
+++ b/include/soc/mscc/ocelot.h
@@ -101,6 +101,7 @@
 #define OCELOT_TAG_LEN			16
 #define OCELOT_SHORT_PREFIX_LEN		4
 #define OCELOT_LONG_PREFIX_LEN		16
+#define OCELOT_TOTAL_TAG_LEN	(OCELOT_SHORT_PREFIX_LEN + OCELOT_TAG_LEN)
 
 #define OCELOT_SPEED_2500		0
 #define OCELOT_SPEED_1000		1
@@ -672,9 +673,6 @@ void __ocelot_rmw_ix(struct ocelot *ocelot, u32 val, u32 mask, u32 reg,
 int ocelot_regfields_init(struct ocelot *ocelot,
 			  const struct reg_field *const regfields);
 struct regmap *ocelot_regmap_init(struct ocelot *ocelot, struct resource *res);
-void ocelot_configure_cpu(struct ocelot *ocelot, int npi,
-			  enum ocelot_tag_prefix injection,
-			  enum ocelot_tag_prefix extraction);
 int ocelot_init(struct ocelot *ocelot);
 void ocelot_deinit(struct ocelot *ocelot);
 void ocelot_init_port(struct ocelot *ocelot, int port);