Merge branch 'net-dsa-tag_dsa-unify-regular-and-ethertype-dsa-taggers'

Tobias Waldekranz says:

====================
net: dsa: tag_dsa: Unify regular and ethertype DSA taggers

The first patch ports tag_edsa.c's handling of IGMP/MLD traps to
tag_dsa.c. That way, we start from two logically equivalent taggers
that are then merged. The second commit does the heavy lifting of
actually fusing tag_dsa.c and tag_edsa.c. The final one just follows
up with some clean up of existing comments.

v2 -> v3:
  - Add the first patch described above as suggested by Andrew.
  - Better documentation of TO_SNIFFER and FORWARD tags.
  - Spelling.

v1 -> v2:
  - Fixed some grammar and whitespace errors.
  - Removed unnecessary default value in Kconfig.
  - Removed unnecessary #ifdef.
  - Split out comment fixes from functional changes.
  - Fully document enum dsa_code.
====================

Link: https://lore.kernel.org/r/20201114234558.31203-1-tobias@waldekranz.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/dsa/Kconfig

@@ -68,14 +68,19 @@ config NET_DSA_TAG_GSWIP
 	  Say Y or M if you want to enable support for tagging frames for the
 	  Lantiq / Intel GSWIP switches.
 
+config NET_DSA_TAG_DSA_COMMON
+	tristate
+
 config NET_DSA_TAG_DSA
 	tristate "Tag driver for Marvell switches using DSA headers"
+	select NET_DSA_TAG_DSA_COMMON
 	help
 	  Say Y or M if you want to enable support for tagging frames for the
 	  Marvell switches which use DSA headers.
 
 config NET_DSA_TAG_EDSA
 	tristate "Tag driver for Marvell switches using EtherType DSA headers"
+	select NET_DSA_TAG_DSA_COMMON
 	help
 	  Say Y or M if you want to enable support for tagging frames for the
 	  Marvell switches which use EtherType DSA headers.

net/dsa/Makefile

@@ -7,8 +7,7 @@ dsa_core-y += dsa.o dsa2.o master.o port.o slave.o switch.o
 obj-$(CONFIG_NET_DSA_TAG_8021Q) += tag_8021q.o
 obj-$(CONFIG_NET_DSA_TAG_AR9331) += tag_ar9331.o
 obj-$(CONFIG_NET_DSA_TAG_BRCM_COMMON) += tag_brcm.o
-obj-$(CONFIG_NET_DSA_TAG_DSA) += tag_dsa.o
-obj-$(CONFIG_NET_DSA_TAG_EDSA) += tag_edsa.o
+obj-$(CONFIG_NET_DSA_TAG_DSA_COMMON) += tag_dsa.o
 obj-$(CONFIG_NET_DSA_TAG_GSWIP) += tag_gswip.o
 obj-$(CONFIG_NET_DSA_TAG_HELLCREEK) += tag_hellcreek.o
 obj-$(CONFIG_NET_DSA_TAG_KSZ) += tag_ksz.o

net/dsa/tag_edsa.c

-// SPDX-License-Identifier: GPL-2.0+
-/*
- * net/dsa/tag_edsa.c - Ethertype DSA tagging
- * Copyright (c) 2008-2009 Marvell Semiconductor
- */
-
-#include <linux/etherdevice.h>
-#include <linux/list.h>
-#include <linux/slab.h>
-
-#include "dsa_priv.h"
-
-#define DSA_HLEN	4
-#define EDSA_HLEN	8
-
-#define FRAME_TYPE_TO_CPU	0x00
-#define FRAME_TYPE_FORWARD	0x03
-
-#define TO_CPU_CODE_MGMT_TRAP		0x00
-#define TO_CPU_CODE_FRAME2REG		0x01
-#define TO_CPU_CODE_IGMP_MLD_TRAP	0x02
-#define TO_CPU_CODE_POLICY_TRAP		0x03
-#define TO_CPU_CODE_ARP_MIRROR		0x04
-#define TO_CPU_CODE_POLICY_MIRROR	0x05
-
-static struct sk_buff *edsa_xmit(struct sk_buff *skb, struct net_device *dev)
-{
-	struct dsa_port *dp = dsa_slave_to_port(dev);
-	u8 *edsa_header;
-
-	/*
-	 * Convert the outermost 802.1q tag to a DSA tag and prepend
-	 * a DSA ethertype field is the packet is tagged, or insert
-	 * a DSA ethertype plus DSA tag between the addresses and the
-	 * current ethertype field if the packet is untagged.
-	 */
-	if (skb->protocol == htons(ETH_P_8021Q)) {
-		skb_push(skb, DSA_HLEN);
-
-		memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
-
-		/*
-		 * Construct tagged FROM_CPU DSA tag from 802.1q tag.
-		 */
-		edsa_header = skb->data + 2 * ETH_ALEN;
-		edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
-		edsa_header[1] = ETH_P_EDSA & 0xff;
-		edsa_header[2] = 0x00;
-		edsa_header[3] = 0x00;
-		edsa_header[4] = 0x60 | dp->ds->index;
-		edsa_header[5] = dp->index << 3;
-
-		/*
-		 * Move CFI field from byte 6 to byte 5.
-		 */
-		if (edsa_header[6] & 0x10) {
-			edsa_header[5] |= 0x01;
-			edsa_header[6] &= ~0x10;
-		}
-	} else {
-		skb_push(skb, EDSA_HLEN);
-
-		memmove(skb->data, skb->data + EDSA_HLEN, 2 * ETH_ALEN);
-
-		/*
-		 * Construct untagged FROM_CPU DSA tag.
-		 */
-		edsa_header = skb->data + 2 * ETH_ALEN;
-		edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
-		edsa_header[1] = ETH_P_EDSA & 0xff;
-		edsa_header[2] = 0x00;
-		edsa_header[3] = 0x00;
-		edsa_header[4] = 0x40 | dp->ds->index;
-		edsa_header[5] = dp->index << 3;
-		edsa_header[6] = 0x00;
-		edsa_header[7] = 0x00;
-	}
-
-	return skb;
-}
-
-static struct sk_buff *edsa_rcv(struct sk_buff *skb, struct net_device *dev,
-				struct packet_type *pt)
-{
-	u8 *edsa_header;
-	int frame_type;
-	int code;
-	int source_device;
-	int source_port;
-
-	if (unlikely(!pskb_may_pull(skb, EDSA_HLEN)))
-		return NULL;
-
-	/*
-	 * Skip the two null bytes after the ethertype.
-	 */
-	edsa_header = skb->data + 2;
-
-	/*
-	 * Check that frame type is either TO_CPU or FORWARD.
-	 */
-	frame_type = edsa_header[0] >> 6;
-
-	switch (frame_type) {
-	case FRAME_TYPE_TO_CPU:
-		code = (edsa_header[1] & 0x6) | ((edsa_header[2] >> 4) & 1);
-
-		/*
-		 * Mark the frame to never egress on any port of the same switch
-		 * unless it's a trapped IGMP/MLD packet, in which case the
-		 * bridge might want to forward it.
-		 */
-		if (code != TO_CPU_CODE_IGMP_MLD_TRAP)
-			skb->offload_fwd_mark = 1;
-
-		break;
-
-	case FRAME_TYPE_FORWARD:
-		skb->offload_fwd_mark = 1;
-		break;
-
-	default:
-		return NULL;
-	}
-
-	/*
-	 * Determine source device and port.
-	 */
-	source_device = edsa_header[0] & 0x1f;
-	source_port = (edsa_header[1] >> 3) & 0x1f;
-
-	skb->dev = dsa_master_find_slave(dev, source_device, source_port);
-	if (!skb->dev)
-		return NULL;
-
-	/*
-	 * If the 'tagged' bit is set, convert the DSA tag to a 802.1q
-	 * tag and delete the ethertype part.  If the 'tagged' bit is
-	 * clear, delete the ethertype and the DSA tag parts.
-	 */
-	if (edsa_header[0] & 0x20) {
-		u8 new_header[4];
-
-		/*
-		 * Insert 802.1q ethertype and copy the VLAN-related
-		 * fields, but clear the bit that will hold CFI (since
-		 * DSA uses that bit location for another purpose).
-		 */
-		new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
-		new_header[1] = ETH_P_8021Q & 0xff;
-		new_header[2] = edsa_header[2] & ~0x10;
-		new_header[3] = edsa_header[3];
-
-		/*
-		 * Move CFI bit from its place in the DSA header to
-		 * its 802.1q-designated place.
-		 */
-		if (edsa_header[1] & 0x01)
-			new_header[2] |= 0x10;
-
-		skb_pull_rcsum(skb, DSA_HLEN);
-
-		/*
-		 * Update packet checksum if skb is CHECKSUM_COMPLETE.
-		 */
-		if (skb->ip_summed == CHECKSUM_COMPLETE) {
-			__wsum c = skb->csum;
-			c = csum_add(c, csum_partial(new_header + 2, 2, 0));
-			c = csum_sub(c, csum_partial(edsa_header + 2, 2, 0));
-			skb->csum = c;
-		}
-
-		memcpy(edsa_header, new_header, DSA_HLEN);
-
-		memmove(skb->data - ETH_HLEN,
-			skb->data - ETH_HLEN - DSA_HLEN,
-			2 * ETH_ALEN);
-	} else {
-		/*
-		 * Remove DSA tag and update checksum.
-		 */
-		skb_pull_rcsum(skb, EDSA_HLEN);
-		memmove(skb->data - ETH_HLEN,
-			skb->data - ETH_HLEN - EDSA_HLEN,
-			2 * ETH_ALEN);
-	}
-
-	return skb;
-}
-
-static const struct dsa_device_ops edsa_netdev_ops = {
-	.name	= "edsa",
-	.proto	= DSA_TAG_PROTO_EDSA,
-	.xmit	= edsa_xmit,
-	.rcv	= edsa_rcv,
-	.overhead = EDSA_HLEN,
-};
-
-MODULE_LICENSE("GPL");
-MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_EDSA);
-
-module_dsa_tag_driver(edsa_netdev_ops);