Subject: [RFC 1/1] net/hsr: Add support for IEC 62439-3 High-availability Seamless Redundancy

From: Arvid Brodin <[email-masked]>
Date: Mon, 12 Mar 2012 20:23:07 +0100

Hello!

I have two wishes with this RFC:

1) General code review. I haven't worked with neither kernel network code nor
   used rcu locking before, so I feel I need a sanity check of the code. Am I
   doing things in a sane way?

   There are some debug printouts and "//" comments in this code. These will be
   removed in the final patch.

2) I have a locking problem that I haven't managed to figure out. This happens
   the first time I send any packet (hsr_dev_xmit() in hsr_device:121, called
   from hsr_device:147). It happens even if I set skb2 to NULL (i.e. only send
   one copy):

=============================================
[ INFO: possible recursive locking detected ]
2.6.37 #118
---------------------------------------------
swapper/0 is trying to acquire lock:
 (_xmit_ETHER#2){+.-...}, at: [<901bf38e>] sch_direct_xmit+0x24/0x152

but task is already holding lock:
 (_xmit_ETHER#2){+.-...}, at: [<901b4d1a>] dev_queue_xmit+0x31e/0x3cc

other info that might help us debug this:
4 locks held by swapper/0:
 #0:  (&n->timer){+.-...}, at: [<9002bc20>] run_timer_softirq+0x98/0x184
 #1:  (rcu_read_lock_bh){.+....}, at: [<901b49fc>] dev_queue_xmit+0x0/0x3cc
 #2:  (_xmit_ETHER#2){+.-...}, at: [<901b4d1a>] dev_queue_xmit+0x31e/0x3cc
 #3:  (rcu_read_lock_bh){.+....}, at: [<901b49fc>] dev_queue_xmit+0x0/0x3cc

stack backtrace:
Call trace:
 [<9001c640>] dump_stack+0x18/0x20
 [<90040eac>] validate_chain+0x40c/0x9ac
 [<90041a58>] __lock_acquire+0x60c/0x670
 [<90042f32>] lock_acquire+0x3a/0x48
 [<902201a4>] _raw_spin_lock+0x20/0x44
 [<901bf38e>] sch_direct_xmit+0x24/0x152
 [<901b4c14>] dev_queue_xmit+0x218/0x3cc
 [<9021c2e0>] slave_xmit+0x10/0x14
 [<9021c540>] hsr_dev_xmit+0x88/0x8c
 [<901b4942>] dev_hard_start_xmit+0x3c6/0x480
 [<901b4d34>] dev_queue_xmit+0x338/0x3cc
 [<901e3cd8>] arp_xmit+0x8/0xc
 [<901e4436>] arp_send+0x2a/0x2c
 [<901e4e74>] arp_solicit+0x15c/0x170
 [<901bad0c>] neigh_timer_handler+0x1c0/0x204
 [<9002bc8a>] run_timer_softirq+0x102/0x184
 [<900287d8>] __do_softirq+0x64/0xe0
 [<9002896a>] do_softirq+0x26/0x48
 [<90028a66>] irq_exit+0x2e/0x64
 [<90019f16>] do_IRQ+0x46/0x5c
 [<90018428>] irq_level0+0x18/0x60
 [<9021cc16>] rest_init+0x72/0x98
 [<9000063c>] start_kernel+0x21c/0x258
 [<00000000>] 0x0

   Any idea why this happens?

And here's the actual patch:

---
 include/linux/if_ether.h |    1 +
 include/linux/if_link.h  |   11 +
 net/Kconfig              |    5 +-
 net/Makefile             |    1 +
 net/hsr/Kconfig          |   84 ++++++++
 net/hsr/Makefile         |    7 +
 net/hsr/hsr_device.c     |  518 ++++++++++++++++++++++++++++++++++++++++++++++
 net/hsr/hsr_device.h     |   22 ++
 net/hsr/hsr_framereg.c   |  157 ++++++++++++++
 net/hsr/hsr_framereg.h   |   23 ++
 net/hsr/hsr_main.c       |  383 ++++++++++++++++++++++++++++++++++
 net/hsr/hsr_netlink.c    |   78 +++++++
 net/hsr/hsr_netlink.h    |   21 ++
 net/hsr/hsr_private.h    |  114 ++++++++++
 14 files changed, 1423 insertions(+), 2 deletions(-)

diff --git a/include/linux/if_ether.h b/include/linux/if_ether.h
index 56d907a..0d0e2f9 100644
--- a/include/linux/if_ether.h
+++ b/include/linux/if_ether.h
@@ -83,6 +83,7 @@
 #define ETH_P_TIPC	0x88CA		/* TIPC 			*/
 #define ETH_P_8021AH	0x88E7          /* 802.1ah Backbone Service Tag */
 #define ETH_P_1588	0x88F7		/* IEEE 1588 Timesync */
+#define ETH_P_HSR	0x88FB		/* IEC 62439-3 HSR/PRP		*/
 #define ETH_P_FCOE	0x8906		/* Fibre Channel over Ethernet  */
 #define ETH_P_TDLS	0x890D          /* TDLS */
 #define ETH_P_FIP	0x8914		/* FCoE Initialization Protocol */
diff --git a/include/linux/if_link.h b/include/linux/if_link.h
index 4b24ff4..3e3efb4 100644
--- a/include/linux/if_link.h
+++ b/include/linux/if_link.h
@@ -391,4 +391,15 @@ struct ifla_port_vsi {
 	__u8 pad[3];
 };
 
+/* HSR section */
+
+enum {
+	IFLA_HSR_UNSPEC,
+	IFLA_HSR_SLAVE1,
+	IFLA_HSR_SLAVE2,
+	__IFLA_HSR_MAX,
+};
+
+#define IFLA_HSR_MAX (__IFLA_HSR_MAX - 1)
+
 #endif /* _LINUX_IF_LINK_H */
diff --git a/net/Kconfig b/net/Kconfig
index e07272d..99d666d 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -216,6 +216,7 @@ source "net/dcb/Kconfig"
 source "net/dns_resolver/Kconfig"
 source "net/batman-adv/Kconfig"
 source "net/openvswitch/Kconfig"
+source "net/hsr/Kconfig"
 
 config RPS
 	boolean
diff --git a/net/Makefile b/net/Makefile
index ad432fa..7d8787f 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -70,3 +70,4 @@ obj-$(CONFIG_CEPH_LIB)		+= ceph/
 obj-$(CONFIG_BATMAN_ADV)	+= batman-adv/
 obj-$(CONFIG_NFC)		+= nfc/
 obj-$(CONFIG_OPENVSWITCH)	+= openvswitch/
+obj-$(CONFIG_HSR)		+= hsr/
diff --git a/net/hsr/Kconfig b/net/hsr/Kconfig
new file mode 100644
index 0000000..895afda
--- /dev/null
+++ b/net/hsr/Kconfig
@@ -0,0 +1,84 @@
+#
+# IEC 62439-3 High-availability Seamless Redundancy
+#
+
+config HSR
+	tristate "High-availability Seamless Redundancy (HSR)"
+	---help---
+	  If you say Y here, then your Linux box will be able to act as a
+	  DANH ("Doubly attached node implementing HSR"). For this to work,
+	  your Linux box needs (at least) two physical Ethernet interfaces,
+	  and you need to enslave these to a virtual hsr interface using the
+	  appropriate user space tool, i.e.:
+
+	  # ip link add name hsr0 type hsr dev1 dev2
+
+	  Your Linux box must be connected as a node in a ring network
+	  together with other HSR capable nodes.
+
+	  All Ethernet frames sent over the hsr device will be sent in both
+	  directions on the ring (over both slave ports), giving a redundant,
+	  instant fail-over network.
+
+	  Each HSR node in the ring acts like a bridge for HSR frames, but
+	  filters frames that have been forwarded earlier.
+
+	  This code is a "best effort" to comply with the HSR standard as
+	  described in IEC 62439-3, but no compliancy tests have been made.
+	  You need to perform any and all necessary tests yourself before
+	  relying on this code in a safety critical system. In particular, the
+	  standard is very diffuse on how to use the Ring ID field in the HSR
+	  tag, and it's probable that this code does not do the right thing.
+
+	  If unsure, say N.
+
+if HAVE_EFFICIENT_UNALIGNED_ACCESS
+
+config NONSTANDARD_HSR
+	bool "HSR: Use efficient tag (breaks HSR standard, read help!)"
+	depends on HSR
+	---help---
+	  The HSR standard specifies a 6-byte HSR tag to be inserted into the
+	  transmitted network frames. This breaks the 32-bit alignment that the
+	  Linux network stack relies on, and would cause kernel panics on
+	  certain architectures. To avoid this, the whole frame payload is
+	  memmoved 2 bytes on reception on these architectures - which is very
+	  inefficient!
+
+	  If you select Y here, 2 bytes of padding is inserted into the HSR tag,
+	  which makes it possible to skip the memmove. This however breaks
+	  compatibility with compliant HSR devices. I.e., either all or none of
+	  the devices in your HSR ring needs to have this option set.
+
+	  Your architecture has HAVE_EFFICIENT_UNALIGNED_ACCESS, so you do not
+	  need this unless you have other nodes in your ring which have this
+	  option set.
+
+	  If unsure, say N.
+
+endif # HAVE_EFFICIENT_UNALIGNED_ACCESS
+if !HAVE_EFFICIENT_UNALIGNED_ACCESS
+
+config NONSTANDARD_HSR
+	bool "HSR: Use efficient tag (breaks HSR standard, read help!)"
+	depends on HSR
+	---help---
+	  The HSR standard specifies a 6-byte HSR tag to be inserted into the
+	  transmitted network frames. This breaks the 32-bit alignment that the
+	  Linux network stack relies on, and would cause kernel panics on
+	  certain architectures. To avoid this, the whole frame payload is
+	  memmoved 2 bytes on reception on these architectures - which is very
+	  inefficient!
+
+	  If you select Y here, 2 bytes of padding is inserted into the HSR tag,
+	  which makes it possible to skip the memmove. This however breaks
+	  compatibility with compliant HSR devices. I.e., either all or none of
+	  the devices in your HSR ring needs to have this option set.
+
+	  Your architecture does not have HAVE_EFFICIENT_UNALIGNED_ACCESS, so
+	  you should seriously consider saying Y here if performance is at all
+	  important to you.
+
+	  If unsure, say N.
+
+endif # !HAVE_EFFICIENT_UNALIGNED_ACCESS
diff --git a/net/hsr/Makefile b/net/hsr/Makefile
new file mode 100644
index 0000000..b68359f
--- /dev/null
+++ b/net/hsr/Makefile
@@ -0,0 +1,7 @@
+#
+# Makefile for HSR
+#
+
+obj-$(CONFIG_HSR)	+= hsr.o
+
+hsr-y			:= hsr_main.o hsr_framereg.o hsr_device.o hsr_netlink.o
diff --git a/net/hsr/hsr_device.c b/net/hsr/hsr_device.c
new file mode 100644
index 0000000..f83bdf5
--- /dev/null
+++ b/net/hsr/hsr_device.c
@@ -0,0 +1,518 @@
+/*
+ * Copyright 2011-2012 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2012 Arvid Brodin, [email-masked]
+ *
+ * This file contains device methods for creating, using and destroying
+ * virtual HSR devices.
+ */
+
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/etherdevice.h>
+#include <linux/if_arp.h>
+#include <linux/rtnetlink.h>
+#include <linux/netfilter.h>
+#include "hsr_framereg.h"
+#include "hsr_private.h"
+
+
+static int is_up(struct net_device *dev)
+{
+	return (dev->flags & IFF_UP);
+}
+
+
+void hsr_check_announce(struct net_device *hsr_dev, struct net_device *slave1,
+						struct net_device *slave2)
+{
+	struct hsr_priv *hsr_priv;
+
+	hsr_priv = netdev_priv(hsr_dev);
+
+	if (!hsr_priv->online && is_up(hsr_dev) &&
+					(is_up(slave1) || is_up(slave2))) {
+		hsr_priv->online = 1;
+		hsr_priv->announce_count = 0;
+		hsr_priv->announce_timer.expires = jiffies +
+					HSR_ANNOUNCE_INTERVAL * HZ / 1000;
+		add_timer(&hsr_priv->announce_timer);
+	} else {
+		hsr_priv->online = 0;
+		del_timer(&hsr_priv->announce_timer);
+	}
+}
+
+static int hsr_dev_open(struct net_device *dev)
+{
+	struct hsr_priv *hsr_priv;
+
+	hsr_priv = netdev_priv(dev);
+
+	dev_open(hsr_priv->slave_data[0].dev_data.dev);
+	dev_open(hsr_priv->slave_data[1].dev_data.dev);
+
+	return 0;
+}
+
+static int hsr_dev_close(struct net_device *dev)
+{
+	// FIXME: reset status of slaves
+	return 0;
+}
+
+
+static void hsr_fill_tag(struct hsr_ethhdr *hsr_ethhdr, struct hsr_priv *hsr_priv)
+{
+	u16 path;
+	u16 LSDU_size;
+	unsigned long irqflags;
+
+	/*
+	 * IEC 62439-1, p 48, says the 4-bit "path" field can take values
+	 * between 0001-1001 ("ring identifier", for regular HSR frames),
+	 * or 1111 ("HSR management", supervision frames). Unfortunately, the
+	 * spec writers forgot to explain what a "ring identifier" is, or
+	 * how it is used. So we just set this to 0001 for regular frames,
+	 * and 1111 for supervision frames.
+	 */
+	path = 0x1;
+
+	/*
+	 * IEC 62439-1, p 12: "The link service data unit in an Ethernet frame
+	 * is the content of the frame located between the Length/Type field
+	 * and the Frame Check Sequence."
+	 *
+	 * IEC 62439-3, p 48, specifies the "original LPDU" to include the
+	 * original "LT" field (what "LT" means is not explained anywhere as
+	 * far as I can see - perhaps "Length/Type"?). So LSDU_size might
+	 * equal original length + 2.
+	 *   Also, the fact that this field is not used anywhere (might be used
+	 * by a RedBox connecting HSR and PRP nets?) means I cannot test its
+	 * correctness. Instead of guessing, I set this to 0 here, to make any
+	 * problems immediately apparent. Anyone using this driver with PRP/HSR
+	 * RedBoxes might need to fix this...
+	 */
+	LSDU_size = 0;
+	hsr_ethhdr->hsr_tag.path_and_LSDU_size =
+					htons((u16) (path << 12) | LSDU_size);
+
+	spin_lock_irqsave(&hsr_priv->seqlock, irqflags);
+	hsr_ethhdr->hsr_tag.sequence_nr = htons(hsr_priv->sequence_nr);
+	hsr_priv->sequence_nr++;
+	spin_unlock_irqrestore(&hsr_priv->seqlock, irqflags);
+
+	hsr_ethhdr->hsr_tag.encap_proto = hsr_ethhdr->ethhdr.h_proto;
+
+	hsr_ethhdr->ethhdr.h_proto = htons(ETH_P_HSR);
+}
+
+static int slave_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	skb->dev = dev;
+	skb->priority = 1; // FIXME: what does this mean?
+
+	return dev_queue_xmit(skb);
+}
+
+
+static int hsr_dev_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct hsr_priv *hsr_priv;
+	struct hsr_ethhdr *hsr_ethhdr;
+	struct sk_buff *skb2;
+	int res1, res2;
+
+	hsr_priv = netdev_priv(dev);
+	hsr_ethhdr = (struct hsr_ethhdr *) skb->data;
+
+	if ((ntohs(skb->protocol) != ETH_P_HSR) ||
+			(ntohs(hsr_ethhdr->ethhdr.h_proto) != ETH_P_HSR)) {
+
+		hsr_fill_tag(hsr_ethhdr, hsr_priv);
+		skb->protocol = htons(ETH_P_HSR);
+	}
+
+	skb2 = skb_clone(skb, GFP_ATOMIC);
+
+	res1 = NET_XMIT_DROP;
+	res2 = NET_XMIT_DROP;
+	if (!register_frame(&hsr_priv->slave_data[0].dev_data, skb))
+		res1 = slave_xmit(skb, hsr_priv->slave_data[0].dev_data.dev);
+	if (skb2 && !register_frame(&hsr_priv->slave_data[1].dev_data, skb2))
+		res2 = slave_xmit(skb2, hsr_priv->slave_data[1].dev_data.dev);
+
+	if (likely(res1 == NET_XMIT_SUCCESS || res1 == NET_XMIT_CN ||
+			res2 == NET_XMIT_SUCCESS || res2 == NET_XMIT_CN)) {
+		hsr_priv->dev_data.dev->stats.tx_packets++;
+		hsr_priv->dev_data.dev->stats.tx_bytes += skb->len;
+	} else
+		hsr_priv->dev_data.dev->stats.tx_dropped++;
+
+	return NETDEV_TX_OK;
+}
+
+
+static int hsr_header_create(struct sk_buff *skb, struct net_device *dev,
+					unsigned short type,
+					const void *daddr, const void *saddr,
+					unsigned int len)
+{
+	int res;
+
+	/* Make room for the HSR tag now. We will fill it in later (in
+	   hsr_dev_xmit) */
+	skb_push(skb, HSR_TAGLEN);
+	res = eth_header(skb, dev, type, daddr, saddr, len + HSR_TAGLEN);
+	if (res <= 0)
+		return res;
+	skb_reset_mac_header(skb);
+
+	return res + HSR_TAGLEN;
+}
+
+
+static const struct header_ops hsr_header_ops = {
+	.create	 = hsr_header_create,
+	.parse	 = eth_header_parse,
+};
+
+
+static int set_mac_address(struct net_device *dev, const char new_mac[ETH_ALEN])
+{
+	struct sockaddr sockaddr;
+	int res;
+
+	memcpy(sockaddr.sa_data, new_mac, dev->addr_len);
+	sockaddr.sa_family = dev->type;
+	res = dev_set_mac_address(dev, &sockaddr);
+
+	return res;
+}
+
+
+static void send_hsr_supervision_frame(struct net_device *hsr_dev, u8 type)
+{
+	struct hsr_priv *hsr_priv;
+	struct sk_buff *skb;
+	struct hsr_ethhdr *hsr_ethhdr;
+	unsigned char *MacAddressA;
+	u16 path, HSR_Ver, HSR_TLV_Length;
+	unsigned long irqflags;
+
+	skb = alloc_skb(sizeof(struct ethhdr) +
+				sizeof(struct hsr_supervision_tag) +
+				LL_RESERVED_SPACE(hsr_dev) +
+				hsr_dev->needed_tailroom, GFP_ATOMIC);
+	if (skb == NULL)
+		return;
+
+	hsr_priv = netdev_priv(hsr_dev);
+
+	skb_reserve(skb, LL_RESERVED_SPACE(hsr_dev));
+	skb_reset_network_header(skb);
+	MacAddressA = (unsigned char *) skb_put(skb, ETH_ALEN);
+	memcpy(MacAddressA, hsr_dev->dev_addr, ETH_ALEN);
+	*MacAddressA = 0xff;
+
+	skb->dev = hsr_dev;
+	skb->protocol = htons(ETH_P_HSR);
+
+	if (dev_hard_header(skb, skb->dev, ETH_P_HSR, hsr_multicast_addr,
+					skb->dev->dev_addr, skb->len) < 0)
+		goto out;
+
+	hsr_ethhdr = (struct hsr_ethhdr *) skb->data;
+
+	path = 0x0f;
+	HSR_Ver = 0;
+	hsr_ethhdr->hsr_tag.path_and_LSDU_size = htons(path << 12 | HSR_Ver);
+
+	spin_lock_irqsave(&hsr_priv->seqlock, irqflags);
+	hsr_ethhdr->hsr_tag.sequence_nr = htons(hsr_priv->sequence_nr);
+	hsr_priv->sequence_nr++;
+	spin_unlock_irqrestore(&hsr_priv->seqlock, irqflags);
+
+	HSR_TLV_Length = 12;
+	hsr_ethhdr->hsr_tag.encap_proto = htons(type << 8 | HSR_TLV_Length);
+
+	dev_queue_xmit(skb);
+	return;
+
+out:
+	kfree_skb(skb);
+}
+
+
+/*
+ * Announce (supervision frame) timer function
+ */
+static void hsr_announce(unsigned long data)
+{
+	struct hsr_priv *hsr_priv;
+
+	hsr_priv = (struct hsr_priv *) data;
+
+	if (hsr_priv->announce_count < 3) {
+		send_hsr_supervision_frame(hsr_priv->dev_data.dev, 22);
+		hsr_priv->announce_count++;
+	} else
+		send_hsr_supervision_frame(hsr_priv->dev_data.dev, 23);
+
+	if (hsr_priv->announce_count < 3)
+		hsr_priv->announce_timer.expires = jiffies +
+					HSR_ANNOUNCE_INTERVAL * HZ / 1000;
+	else
+		hsr_priv->announce_timer.expires = jiffies +
+					HSR_LIFE_CHECK_INTERVAL * HZ / 1000;
+
+	if (hsr_priv->online)
+		add_timer(&hsr_priv->announce_timer);
+}
+
+
+
+
+static void restore_slaves(struct net_device *hsr_dev)
+{
+	struct hsr_priv *hsr_priv;
+	struct net_device *slave[2];
+	int i;
+	int res;
+
+	hsr_priv = netdev_priv(hsr_dev);
+	for (i = 0; i < 2; i++)
+		slave[i] = hsr_priv->slave_data[i].dev_data.dev;
+
+	rtnl_lock();
+
+	/* Restore promiscuity */
+	for (i = 0; i < 2; i++) {
+		if (!hsr_priv->slave_data[i].promisc)
+			continue;
+		res = dev_set_promiscuity(slave[i],
+					-hsr_priv->slave_data[i].promisc);
+		if (res)
+			pr_info("HSR: Cannot restore promiscuity (%s, %d)\n",
+							slave[i]->name,
+							res);
+	}
+
+	/* Restore MAC addresses */
+	for (i = 0; i < 2; i++) {
+		if (!memcmp(hsr_priv->slave_data[i].orig_mac,
+							slave[i]->dev_addr,
+							slave[i]->addr_len))
+			continue;
+		dev_close(slave[i]);
+		res = set_mac_address(slave[i],
+					hsr_priv->slave_data[i].orig_mac);
+		if (res)
+			pr_info("HSR: Could not restore MAC address "
+							"(%s, %d)\n",
+							slave[i]->name,
+							res);
+		}
+
+	/* Restore up state */
+	for (i = 0; i < 2; i++)
+		if (hsr_priv->slave_data[i].was_up)
+			dev_open(slave[i]);
+		else
+			dev_close(slave[i]);
+
+	rtnl_unlock();
+}
+
+static void reclaim_hsr_dev(struct rcu_head *rh)
+{
+	struct hsr_priv *hsr_priv;
+
+	hsr_priv = container_of(rh, struct hsr_priv, rcu_head);
+	free_netdev(hsr_priv->dev_data.dev);
+}
+
+/*
+ * According to comments in the declaration of struct net_device, this function
+ * is "Called from unregister, can be used to call free_netdev". Ok then...
+ */
+static void hsr_dev_destroy(struct net_device *hsr_dev)
+{
+	struct hsr_priv *hsr_priv;
+
+	hsr_priv = netdev_priv(hsr_dev);
+
+	unregister_hsr_master(hsr_priv);    /* calls list_del_rcu on hsr_priv */
+	restore_slaves(hsr_dev);
+	call_rcu(&hsr_priv->rcu_head, reclaim_hsr_dev);   /* reclaim hsr_priv */
+}
+
+static struct net_device_ops hsr_device_ops = {
+	.ndo_open = hsr_dev_open,
+	.ndo_stop = hsr_dev_close,
+	.ndo_start_xmit = hsr_dev_xmit,
+};
+
+
+void hsr_dev_setup(struct net_device *dev)
+{
+	random_ether_addr(dev->dev_addr);
+
+	ether_setup(dev);
+	dev->header_ops		 = &hsr_header_ops;
+	dev->netdev_ops		 = &hsr_device_ops;
+	dev->hard_header_len	+= HSR_TAGLEN;
+	dev->mtu		-= HSR_TAGLEN;
+	dev->tx_queue_len	 = 0;
+
+	dev->destructor = hsr_dev_destroy;
+}
+
+
+/*
+ * If dev is a HSR master, return 1; otherwise, return 0.
+ */
+int is_hsr_master(struct net_device *dev)
+{
+	return (dev->netdev_ops->ndo_start_xmit == hsr_dev_xmit);
+}
+
+static int check_slave_ok(struct net_device *dev)
+{
+	/* Don't allow HSR on non-ethernet like devices */
+	if ((dev->flags & IFF_LOOPBACK) || (dev->type != ARPHRD_ETHER) ||
+						(dev->addr_len != ETH_ALEN)) {
+		pr_info("%s: Cannot enslave loopback or non-ethernet device\n",
+								dev->name);
+		return -EINVAL;
+	}
+
+	/* Don't allow enslaving hsr devices */
+	if (is_hsr_master(dev)) {
+		pr_info("%s: Don't try to create trees of hsr devices!\n",
+								dev->name);
+		return -ELOOP;
+	}
+
+	/* FIXME: What about VLAN devices, bonded devices, etc? */
+
+	return 0;
+}
+
+static void init_dev_data(struct hsr_dev_data *dev_data, struct net_device *dev)
+{
+	dev_data->dev = dev;
+	INIT_LIST_HEAD(&dev_data->frame_db);
+}
+
+int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *slave[2])
+{
+	struct hsr_priv *hsr_priv;
+	struct hsr_slave_data *mac_slave_data1, *mac_slave_data2;
+	int i;
+	int res;
+
+	hsr_priv = netdev_priv(hsr_dev);
+	init_dev_data(&hsr_priv->dev_data, hsr_dev);
+	for (i = 0; i < 2; i++)
+		init_dev_data(&hsr_priv->slave_data[i].dev_data, slave[i]);
+
+	spin_lock_init(&hsr_priv->seqlock);
+	hsr_priv->sequence_nr = 0;
+
+	init_timer(&hsr_priv->announce_timer);
+	hsr_priv->announce_timer.function = hsr_announce;
+	hsr_priv->announce_timer.data = (unsigned long) hsr_priv;
+
+
+/*
+ * FIXME: do I need to set the value of these?
+ *
+ * - hsr_dev->flags
+ * - hsr_dev->priv_flags
+ */
+
+	for (i = 0; i < 2; i++) {
+		res = check_slave_ok(slave[i]);
+		if (res)
+			return res;
+	}
+
+	hsr_dev->features = slave[0]->features & slave[1]->features;
+
+	/* Save/init data needed for restore */
+	for (i = 0; i < 2; i++) {
+		hsr_priv->slave_data[i].was_up = slave[i]->flags & IFF_UP;
+		memcpy(hsr_priv->slave_data[i].orig_mac, slave[i]->dev_addr,
+								ETH_ALEN);
+		hsr_priv->slave_data[i].promisc = 0;
+	}
+
+	/* MAC addresses */
+	if ((!slave[1]->netdev_ops->ndo_set_mac_address) &&
+				(slave[0]->netdev_ops->ndo_set_mac_address)) {
+		mac_slave_data1 = &hsr_priv->slave_data[1];
+		mac_slave_data2 = &hsr_priv->slave_data[0];
+	} else {
+		mac_slave_data1 = &hsr_priv->slave_data[0];
+		mac_slave_data2 = &hsr_priv->slave_data[1];
+	}
+
+	/* Set hsr_dev's MAC address to that of mac_slave1 */
+	memcpy(hsr_dev->dev_addr, mac_slave_data1->dev_data.dev->dev_addr,
+							hsr_dev->addr_len);
+
+	/* Set mac_slave2's MAC address to that of the hsr device and slave1 */
+	if (!mac_slave_data2->dev_data.dev->netdev_ops->ndo_set_mac_address) {
+		pr_info("None of the slaves support changing MAC address; at "
+			 "least one slave must support this for HSR\n");
+		return -EOPNOTSUPP;
+	}
+	dev_close(mac_slave_data2->dev_data.dev);
+	res = set_mac_address(mac_slave_data2->dev_data.dev, hsr_dev->dev_addr);
+	if (res) {
+		pr_info("HSR: dev_set_mac_address failed (%s, %d)\n",
+					mac_slave_data2->dev_data.dev->name,
+					res);
+		goto fail;
+	}
+	if (mac_slave_data2->was_up)
+		dev_open(mac_slave_data2->dev_data.dev);
+
+	/* MTU */
+	for (i = 0; i < 2; i++)
+		if (slave[i]->mtu < hsr_dev->mtu)
+			hsr_dev->mtu = slave[i]->mtu;
+
+
+	/* Promiscuity */
+	for (i = 0; i < 2; i++) {
+		res = dev_set_promiscuity(slave[i], 1);
+		if (res) {
+			pr_info("HSR: Cannot set promiscuous mode (%s, %d)\n",
+								slave[i]->name,
+								res);
+			goto fail;
+		}
+		/* Remember what we have done so we can restore it later */
+		hsr_priv->slave_data[i].promisc = 1;
+	}
+
+	res = register_netdevice(hsr_dev);
+	if (res)
+		goto fail;
+
+	register_hsr_master(hsr_priv);
+
+	return 0;
+
+fail:
+	restore_slaves(hsr_dev);
+	return res;
+}
diff --git a/net/hsr/hsr_device.h b/net/hsr/hsr_device.h
new file mode 100644
index 0000000..a1adab4
--- /dev/null
+++ b/net/hsr/hsr_device.h
@@ -0,0 +1,22 @@
+/*
+ * Copyright 2011-2012 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2012 Arvid Brodin, [email-masked]
+ */
+
+#ifndef __HSR_DEVICE_H
+#define __HSR_DEVICE_H
+
+#include <linux/netdevice.h>
+
+void hsr_dev_setup(struct net_device *dev);
+int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *dev1,
+						struct net_device *dev2);
+
+#endif /* __HSR_DEVICE_H */
diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c
new file mode 100644
index 0000000..8747242
--- /dev/null
+++ b/net/hsr/hsr_framereg.c
@@ -0,0 +1,157 @@
+/*
+ * Copyright 2011-2012 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2012 Arvid Brodin, [email-masked]
+ *
+ * The HSR spec says never to forward the same frame twice on the same
+ * interface. A frame is identified by its source MAC address and its HSR
+ * sequence number. This code keeps track of senders and their sequence numbers
+ * to allow filtering of duplicate frames.
+ */
+
+#include <linux/if_ether.h>
+#include <linux/etherdevice.h>
+#include <linux/slab.h>
+#include <linux/rculist.h>
+#include "hsr_private.h"
+#include "hsr_framereg.h"
+
+
+/*
+	TODO: use hash lists for mac addresses (linux/jhash.h)?
+*/
+
+struct mac_entry {
+	struct list_head mac_list;
+	unsigned char addr[ETH_ALEN];
+	unsigned long timestamp;
+	u16 last_seq;
+	struct rcu_head rcu_head;
+};
+
+/*
+ * Search for mac entry. Caller must hold rcu read lock.
+ */
+static struct mac_entry *find_mac_entry(struct list_head *frame_db,
+						unsigned char addr[ETH_ALEN])
+{
+	struct mac_entry *mac_entry;
+
+	list_for_each_entry_rcu(mac_entry, frame_db, mac_list)
+		if (!compare_ether_addr(mac_entry->addr, addr))
+			return mac_entry;
+
+	return NULL;
+}
+
+
+/*
+ * above(a, b) - return 1 if a > b, 0 otherwise.
+ * Uses C 16-bit unsigned arithmetic, with differences > (1 << 15) interpreted
+ * as negative.
+ */
+#define	MAX_RANGE_DIFF	(1 << 15)
+static int above(u16 a, u16 b)
+{
+	if ((u16) (a - b) == (u16) (b - a))
+		return (a > b);
+	return (((u16) (a - b) > (u16) 0) &&
+		((u16) (a - b) <= (u16) MAX_RANGE_DIFF));
+}
+#define below(a, b)		above((b), (a))
+#define above_or_equal(a, b)	(!below((a), (b)))
+#define below_or_equal(a, b)	(!above((a), (b)))
+
+
+/*
+ * Parameters:
+ *	'skb' is a HSR Ethernet frame (with a HSR tag inserted), with a valid
+ *	ethhdr->h_source address and skb->mac_header set.
+ *
+ * Return:
+ *	 1 if frame can be shown to have been sent recently on this interface,
+ *	 0 otherwise, or
+ *	-1 on error
+ */
+int register_frame(struct hsr_dev_data *dev_data, struct sk_buff *skb)
+{
+	struct mac_entry *mac_entry;
+	struct hsr_ethhdr *hsr_ethhdr;
+
+	if (!skb_mac_header_was_set(skb)) {
+		printk(KERN_INFO "%s:%d: MAC header not set\n", __func__, __LINE__);
+		return -1;
+	}
+	hsr_ethhdr = (struct hsr_ethhdr *) skb_mac_header(skb);
+
+	rcu_read_lock();
+	mac_entry = find_mac_entry(&dev_data->frame_db, hsr_ethhdr->ethhdr.h_source);
+	if (!mac_entry) {
+		rcu_read_unlock();
+
+		mac_entry = kmalloc(sizeof(*mac_entry), GFP_ATOMIC);
+		if (!mac_entry)
+			return -1;
+
+		memcpy(mac_entry->addr, hsr_ethhdr->ethhdr.h_source, ETH_ALEN);
+		mac_entry->last_seq = hsr_ethhdr->hsr_tag.sequence_nr;
+		mac_entry->timestamp = jiffies;
+		list_add_tail_rcu(&mac_entry->mac_list, &dev_data->frame_db);
+
+		return 0;
+	}
+
+	if (below_or_equal(hsr_ethhdr->hsr_tag.sequence_nr, mac_entry->last_seq)) {
+		rcu_read_unlock();
+		return 1;
+	}
+
+	mac_entry->last_seq = hsr_ethhdr->hsr_tag.sequence_nr;
+	mac_entry->timestamp = jiffies;
+	rcu_read_unlock();
+	return 0;
+}
+
+/*
+ * Caller must hold rcu read lock.
+ */
+void update_node_seqnr(struct list_head *frame_db, u8 ethaddr[ETH_ALEN],
+							u16 sequence_nr)
+{
+	struct mac_entry *mac_entry;
+
+	mac_entry = find_mac_entry(frame_db, ethaddr);
+	if (mac_entry) {
+		mac_entry->last_seq = sequence_nr;
+		mac_entry->timestamp = jiffies;
+	}
+}
+
+
+static void mac_entry_reclaim(struct rcu_head *rh)
+{
+	kfree(container_of(rh, struct mac_entry, rcu_head));
+}
+
+/*
+ * Remove stale sequence_nr records. Called by timer every
+ * HSR_LIFE_CHECK_INTERVAL (two seconds or so). This is also the only function
+ * that removes mac_entries; it shouldn't need to be rcu_read_lock():ed.
+ */
+void prune_mac_entries(struct list_head *frame_db)
+{
+	struct mac_entry *mac_entry, *mac_entry_next;
+
+	list_for_each_entry_safe(mac_entry, mac_entry_next, frame_db, mac_list)
+		if (time_after(jiffies, mac_entry->timestamp +
+					HSR_NODE_FORGET_TIME * HZ / 1000)) {
+			list_del_rcu(&mac_entry->mac_list);
+			call_rcu(&mac_entry->rcu_head, mac_entry_reclaim);
+		}
+}
diff --git a/net/hsr/hsr_framereg.h b/net/hsr/hsr_framereg.h
new file mode 100644
index 0000000..970181e
--- /dev/null
+++ b/net/hsr/hsr_framereg.h
@@ -0,0 +1,23 @@
+/*
+ * Copyright 2011-2012 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2012 Arvid Brodin, [email-masked]
+ */
+
+#ifndef _HSR_FRAMEREG_H
+#define _HSR_FRAMEREG_H
+
+#include "hsr_private.h"
+
+int register_frame(struct hsr_dev_data *dev_data, struct sk_buff *skb);
+void update_node_seqnr(struct list_head *frame_db, u8 ethaddr[ETH_ALEN],
+							u16 sequence_nr);
+void prune_mac_entries(struct list_head *frame_db);
+
+#endif /* _HSR_FRAMEREG_H */
diff --git a/net/hsr/hsr_main.c b/net/hsr/hsr_main.c
new file mode 100644
index 0000000..dda5062
--- /dev/null
+++ b/net/hsr/hsr_main.c
@@ -0,0 +1,383 @@
+/*
+ * Copyright 2011-2012 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2012 Arvid Brodin, [email-masked]
+ *
+ * In addition to routines for registering and unregistering HSR support, this
+ * file also contains the receive routine that handles all incoming frames with
+ * Ethertype (protocol) ETH_P_HSR.
+ */
+
+#include <linux/netdevice.h>
+#include <linux/rculist.h>
+#include <linux/timer.h>
+#include <linux/etherdevice.h>
+#include "hsr_private.h"
+#include "hsr_framereg.h"
+#include "hsr_netlink.h"
+
+
+/* Multicast address for HSR Supervision frames */
+const u8 hsr_multicast_addr[ETH_ALEN] = {0x01, 0x15, 0x4e, 0x00, 0x01, 0x00};
+
+
+/* List of all registered virtual HSR devices */
+static LIST_HEAD(hsr_list);
+
+void register_hsr_master(struct hsr_priv *hsr_priv)
+{
+	list_add_tail_rcu(&hsr_priv->hsr_list, &hsr_list);
+}
+
+void unregister_hsr_master(struct hsr_priv *hsr_priv)
+{
+	struct hsr_priv *hsr_priv_it;
+
+	list_for_each_entry(hsr_priv_it, &hsr_list, hsr_list)
+		if (hsr_priv_it == hsr_priv) {
+			list_del_rcu(&hsr_priv_it->hsr_list);
+			return;
+		}
+}
+
+
+/*
+ * If dev is a HSR slave device, return the virtual master device. Return NULL
+ * otherwise.
+ */
+static struct hsr_priv *get_hsr_master(struct net_device *dev)
+{
+	struct hsr_priv *hsr_priv;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(hsr_priv, &hsr_list, hsr_list)
+		if ((dev == hsr_priv->slave_data[0].dev_data.dev) ||
+				(dev == hsr_priv->slave_data[1].dev_data.dev)) {
+			rcu_read_unlock();
+			return hsr_priv;
+		}
+
+	rcu_read_unlock();
+	return NULL;
+}
+
+/*
+ * If dev is a HSR slave device, return the other slave device. Return NULL
+ * otherwise.
+ */
+static struct hsr_slave_data *get_other_slave(struct hsr_priv *hsr_priv,
+							struct net_device *dev)
+{
+	if (dev == hsr_priv->slave_data[0].dev_data.dev)
+		return (&hsr_priv->slave_data[1]);
+	if (dev == hsr_priv->slave_data[1].dev_data.dev)
+		return (&hsr_priv->slave_data[0]);
+
+	return NULL;
+}
+
+
+static int hsr_netdev_notify(struct notifier_block *nb, unsigned long event, void *ptr)
+{
+
+/*
+ * Should do:
+ *
+ * - error monitoring (broken link)
+ * - slave monitoring (disallow down, reconfiguring ?)
+
+	register_netdevice_notifier(...);
+	NETDEV_GOING_DOWN
+	NETDEV_CHANGEADDR
+	NETDEV_CHANGE (dev->flags)
+	NETDEV_UNREGISTER
+ */
+
+	struct net_device *slave, *other_slave;
+	struct hsr_priv *hsr_priv;
+	struct hsr_slave_data *other_data;
+
+	hsr_priv = get_hsr_master(ptr);
+	if (hsr_priv) {
+		slave = ptr;
+		other_data = get_other_slave(hsr_priv, slave);
+		other_slave = other_data->dev_data.dev;
+	} else {
+		if (!is_hsr_master(ptr))
+			return NOTIFY_DONE;
+		hsr_priv = netdev_priv(ptr);
+		slave = hsr_priv->slave_data[0].dev_data.dev;
+		other_slave = hsr_priv->slave_data[1].dev_data.dev;
+	}
+
+	switch (event) {
+	case NETDEV_UP:
+	case NETDEV_DOWN:
+//		printk(KERN_INFO "Got %s event\n", ((struct net_device *) ptr)->name);
+		hsr_check_announce(hsr_priv->dev_data.dev, slave, other_slave);
+	}
+
+	return NOTIFY_DONE;
+}
+
+
+static struct timer_list prune_timer;
+
+static void hsr_prune_nodes(unsigned long data)
+{
+	struct hsr_priv *hsr_priv;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(hsr_priv, &hsr_list, hsr_list) {
+		prune_mac_entries(&hsr_priv->dev_data.frame_db);
+		prune_mac_entries(&hsr_priv->slave_data[0].dev_data.frame_db);
+		prune_mac_entries(&hsr_priv->slave_data[1].dev_data.frame_db);
+	}
+	rcu_read_unlock();
+
+	prune_timer.expires = jiffies + PRUNE_PERIOD * HZ / 1000;
+	add_timer(&prune_timer);
+}
+
+/*
+ * Find all occurences of node with source addr ethaddr, and set their
+ * sequence number to sequence_nr. Used e.g. when a node re-announces itself
+ * after a reboot. Without this, its frames might get filtered until its
+ * entry expires.
+ */
+static void hsr_update_nodes(u8 ethaddr[ETH_ALEN], u16 sequence_nr)
+{
+	struct hsr_priv *hsr_priv;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(hsr_priv, &hsr_list, hsr_list) {
+		update_node_seqnr(&hsr_priv->dev_data.frame_db,
+							ethaddr, sequence_nr);
+		update_node_seqnr(&hsr_priv->slave_data[0].dev_data.frame_db,
+							ethaddr, sequence_nr);
+		update_node_seqnr(&hsr_priv->slave_data[1].dev_data.frame_db,
+							ethaddr, sequence_nr);
+	}
+	rcu_read_unlock();
+}
+
+
+static struct sk_buff *strip_hsr_tag(struct sk_buff *skb)
+{
+	struct hsr_tag *hsr_tag;
+	struct sk_buff *skb2;
+
+	skb2 = skb_share_check(skb, GFP_ATOMIC);
+	if (unlikely(!skb2))
+		goto err_free;
+	skb = skb2;
+
+	if (unlikely(!pskb_may_pull(skb, HSR_TAGLEN)))
+		goto err_free;
+
+	hsr_tag = (struct hsr_tag *) skb->data;
+	skb->protocol = hsr_tag->encap_proto;
+	skb_reset_network_header(skb);  // Huh???
+	skb_pull_rcsum(skb, HSR_TAGLEN);
+
+	return skb;
+
+err_free:
+	kfree_skb(skb);
+	return NULL;
+}
+
+
+/*
+ * The only uses I can see for these HSR supervision frames are:
+ * 1) Use the frames that are sent after node initialization ("HSR_TLV.Type =
+ *    22") to reset any sequence_nr counters belonging to that node.
+ * 2) Perhaps use the LifeCheck frames to detect ring breaks? I.e., the
+ *    LifeCheck frames, since they are periodically sent, will make sure broken
+ *    connections are detected even if the network is completely silent
+ *    otherwise. They don't need any special treatment for this though; just
+ *    register them as normal frames and throw them away.
+ */
+static int handle_supervision_frame(struct hsr_priv *hsr_priv,
+							struct sk_buff *skb)
+{
+	struct hsr_supervision_tag *hsr_stag;
+
+	if (compare_ether_addr(eth_hdr(skb)->h_dest, hsr_multicast_addr))
+		return 0;
+
+	hsr_stag = (struct hsr_supervision_tag *) skb->data;
+	if (ntohs(hsr_stag->path_and_HSR_ver) >> 12 != 0x0f)
+		return 0;
+	if ((hsr_stag->HSR_TLV_Type != 22) && (hsr_stag->HSR_TLV_Type != 23))
+		return 0;
+	if (hsr_stag->HSR_TLV_Length != 12)
+		return 0;
+
+//	printk("%s:%d: got HSR supervision frame (type %d)\n", __FILE__, __LINE__, hsr_stag->HSR_TLV_Type);
+
+	/* Ok, we have a valid HSR supervision frame. */
+	if (hsr_stag->HSR_TLV_Type == 23)
+		hsr_update_nodes(hsr_stag->MacAddressA, hsr_stag->sequence_nr);
+
+	return 1;
+}
+
+
+/*
+ * Implementation somewhat according to IEC-62439-3, p. 43
+ */
+static int hsr_rcv(struct sk_buff *skb, struct net_device *dev,
+			struct packet_type *pt, struct net_device *orig_dev)
+{
+	struct hsr_priv *hsr_priv;
+	struct hsr_slave_data *other_slave_data;
+	int deliver_to_self;
+	struct sk_buff *skb_deliver;
+	int ret;
+
+	hsr_priv = get_hsr_master(dev);
+
+	if (!hsr_priv) {
+		printk(KERN_INFO "HSR: Got HSR frame on non-HSR device; dropping it.\n");
+		kfree_skb(skb);
+		return NET_RX_DROP;
+	}
+
+	/* Receive this frame? */
+	deliver_to_self = 0;
+// ???	if (is_etherdev_addr(hsr_dev, eth_hdr(skb)->h_dest)) {
+	if ((skb->pkt_type == PACKET_HOST) ||
+				(skb->pkt_type == PACKET_MULTICAST) ||
+				(skb->pkt_type == PACKET_BROADCAST))
+		if (register_frame(&hsr_priv->dev_data, skb) == 0)
+			deliver_to_self = 1;
+
+	if (handle_supervision_frame(hsr_priv, skb))
+		deliver_to_self = 0;
+
+	/* Forward this frame? */
+	other_slave_data = NULL;
+	if (skb->pkt_type != PACKET_HOST) {
+		other_slave_data = get_other_slave(hsr_priv, dev);
+		if (register_frame(&other_slave_data->dev_data, skb) == 1)
+			other_slave_data = NULL;
+	}
+
+	if (!deliver_to_self && !other_slave_data) {
+		kfree_skb(skb);
+		return NET_RX_SUCCESS;
+	}
+
+	skb_deliver = skb;
+	if (deliver_to_self && other_slave_data) {
+#if !defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && \
+						!defined(CONFIG_NONSTANDARD_HSR)
+		/* We have to memmove the whole payload below */
+		skb_deliver = skb_copy(skb, GFP_ATOMIC);
+#else
+		skb_deliver = skb_clone(skb, GFP_ATOMIC);
+#endif
+		if (!skb_deliver) {
+			deliver_to_self = 0;
+			hsr_priv->dev_data.dev->stats.rx_dropped++;
+		}
+	}
+
+	if (deliver_to_self) {
+		skb_deliver = strip_hsr_tag(skb_deliver);
+		if (!skb_deliver) {
+			hsr_priv->dev_data.dev->stats.rx_dropped++;
+			goto forward;
+		}
+#if !defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && \
+						!defined(CONFIG_NONSTANDARD_HSR)
+		/*
+		 * skb_deliver should be linear here, after the call to
+		 * skb_copy() in the block above. We need to memmove the
+		 * whole payload to work around alignment problems caused by
+		 * the 6-byte HSR tag.
+		 */
+		memmove(skb_deliver->data - HSR_TAGLEN, skb_deliver->data,
+							skb_deliver->len);
+		skb_deliver->data -= HSR_TAGLEN;
+		skb_deliver->tail -= HSR_TAGLEN;
+		skb_reset_network_header(skb_deliver);
+#endif
+		skb_deliver->dev = hsr_priv->dev_data.dev;
+		ret = netif_rx(skb_deliver);
+		// ^^ Pass frame to hsrX (receive);
+		/*	netif_rx(skb)? VLAN code does this...
+			dev_forward_skb(hsr_dev, skb)? (loopback)
+			netif_receive_skb(skb)? bridge code does this:
+				NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL, netif_receive_skb);
+			What's the "right way"?
+		 */
+		if (ret == NET_RX_DROP)
+			hsr_priv->dev_data.dev->stats.rx_dropped++;
+		else {
+			hsr_priv->dev_data.dev->stats.rx_packets++;
+			hsr_priv->dev_data.dev->stats.rx_bytes += skb->len;
+		}
+	}
+
+forward:
+	if (other_slave_data) {
+		skb_push(skb, ETH_HLEN);
+		skb->dev = other_slave_data->dev_data.dev;
+		dev_queue_xmit(skb);
+	}
+
+	return NET_RX_SUCCESS;
+}
+
+
+static struct packet_type hsr_pt __read_mostly = {
+	.type = htons(ETH_P_HSR),
+	.func = hsr_rcv,
+};
+
+static struct notifier_block hsr_nb = {
+	.notifier_call = hsr_netdev_notify,	/* Slave event notifications */
+};
+
+
+static int __init hsr_init(void)
+{
+	int res;
+
+	BUG_ON(sizeof(struct hsr_tag) != HSR_TAGLEN);
+	BUG_ON(sizeof(struct hsr_ethhdr) != ETH_HLEN + HSR_TAGLEN);
+
+	dev_add_pack(&hsr_pt);
+
+	init_timer(&prune_timer);
+	prune_timer.function = hsr_prune_nodes;
+	prune_timer.data = 0;
+	prune_timer.expires = jiffies + PRUNE_PERIOD * HZ / 1000;
+	add_timer(&prune_timer);
+
+	register_netdevice_notifier(&hsr_nb);
+
+	res = hsr_netlink_init();
+
+	return res;
+}
+
+static void __exit hsr_exit(void)
+{
+	unregister_netdevice_notifier(&hsr_nb);
+	del_timer(&prune_timer);
+	hsr_netlink_exit();
+	dev_remove_pack(&hsr_pt);
+}
+
+module_init(hsr_init);
+module_exit(hsr_exit);
+MODULE_LICENSE("GPL");
diff --git a/net/hsr/hsr_netlink.c b/net/hsr/hsr_netlink.c
new file mode 100644
index 0000000..f391a12
--- /dev/null
+++ b/net/hsr/hsr_netlink.c
@@ -0,0 +1,78 @@
+/*
+ * Copyright 2011-2012 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2012 Arvid Brodin, [email-masked]
+ *
+ * Routines for handling Netlink messages for HSR.
+ */
+
+#include "hsr_netlink.h"
+#include <linux/kernel.h>
+#include <net/rtnetlink.h>
+#include "hsr_private.h"
+
+static const struct nla_policy hsr_policy[IFLA_HSR_MAX + 1] = {
+	[IFLA_HSR_SLAVE1]	= { .type = NLA_U32 },
+	[IFLA_HSR_SLAVE2]	= { .type = NLA_U32 },
+};
+
+
+/*
+ * Here, it seems a netdevice has already been allocated for us, and the
+ * hsr_dev_setup routine has been executed. Nice!
+ */
+static int hsr_newlink(struct net *src_net, struct net_device *dev,
+				struct nlattr *tb[], struct nlattr *data[])
+{
+	struct net_device *link[2];
+
+	if (!data[IFLA_HSR_SLAVE1]) {
+		printk(KERN_INFO "IFLA_HSR_SLAVE1 missing!\n");
+		return -EINVAL;
+	}
+	link[0] = __dev_get_by_index(src_net, nla_get_u32(data[IFLA_HSR_SLAVE1]));
+	if (!data[IFLA_HSR_SLAVE2]) {
+		printk(KERN_INFO "IFLA_HSR_SLAVE2 missing!\n");
+		return -EINVAL;
+	}
+	link[1] = __dev_get_by_index(src_net, nla_get_u32(data[IFLA_HSR_SLAVE2]));
+
+	if (!link[0] || !link[1])
+		return -ENODEV;
+	if (link[0] == link[1])
+		return -EINVAL;
+
+	return hsr_dev_finalize(dev, link);
+}
+
+static struct rtnl_link_ops hsr_link_ops __read_mostly = {
+	.kind		= "hsr",
+	.maxtype	= IFLA_HSR_MAX,
+	.policy		= hsr_policy,
+	.priv_size	= sizeof(struct hsr_priv),
+	.setup		= hsr_dev_setup,
+//	.validate	= vlan_validate,
+	.newlink	= hsr_newlink,
+//	.changelink	= vlan_changelink,
+//	.dellink	= hsr_dellink,  dev->destructor() called automatically?
+//	.get_size	= vlan_get_size,
+//	.fill_info	= vlan_fill_info,
+};
+
+int __init hsr_netlink_init(void)
+{
+	return rtnl_link_register(&hsr_link_ops);
+}
+
+void __exit hsr_netlink_exit(void)
+{
+	rtnl_link_unregister(&hsr_link_ops);
+}
+
+MODULE_ALIAS_RTNL_LINK("hsr");
diff --git a/net/hsr/hsr_netlink.h b/net/hsr/hsr_netlink.h
new file mode 100644
index 0000000..9d8a14d
--- /dev/null
+++ b/net/hsr/hsr_netlink.h
@@ -0,0 +1,21 @@
+/*
+ * Copyright 2011-2012 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2012 Arvid Brodin, [email-masked]
+ */
+
+#ifndef __HSR_NETLINK_H
+#define __HSR_NETLINK_H
+
+#include <linux/module.h>
+
+int __init hsr_netlink_init(void);
+void __exit hsr_netlink_exit(void);
+
+#endif /* __HSR_NETLINK_H */
diff --git a/net/hsr/hsr_private.h b/net/hsr/hsr_private.h
new file mode 100644
index 0000000..2bab99e
--- /dev/null
+++ b/net/hsr/hsr_private.h
@@ -0,0 +1,114 @@
+/*
+ * Copyright 2011-2012 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2012 Arvid Brodin, [email-masked]
+ */
+
+#ifndef _HSR_PRIVATE_H
+#define _HSR_PRIVATE_H
+
+#include <linux/netdevice.h>
+#include <linux/list.h>
+
+
+/*
+ * Time constants as specified in the HSR specification (IEC-62439-3) Table 8.
+ * All values in milliseconds.
+ */
+#define HSR_LIFE_CHECK_INTERVAL		 2000
+#define HSR_NODE_FORGET_TIME		60000
+#define HSR_ANNOUNCE_INTERVAL		  100
+
+/* How often shall we check if node entry is older than HSR_NODE_FORGET_TIME? */
+#define PRUNE_PERIOD			 5000
+
+/*
+ * HSR Tag.
+ * As defined in IEC-62439-3, the HSR tag is really { ethertype = 0x88FB, path,
+ * LSDU_size, sequence Nr }. But we let eth_header() create { h_dest, h_source,
+ * h_proto = 0x88FB }, and add { path, LSDU_size, sequence Nr, encapsulated
+ * protocol } instead.
+ */
+#ifdef CONFIG_NONSTANDARD_HSR
+#define HSR_TAGLEN	8
+#else
+#define HSR_TAGLEN	6
+#endif
+struct hsr_tag {
+/*
+	This is nice but I'm not sure it is "portably compatible" with
+	endianness swaps:
+	__be16		path:4;
+	__be16		LSDU_size:12;
+*/
+	__be16		path_and_LSDU_size;
+	__be16		sequence_nr;
+	__be16		encap_proto;
+#ifdef CONFIG_NONSTANDARD_HSR
+	__be16		padding;
+#endif
+} __attribute__((packed));
+
+struct hsr_ethhdr {
+	struct ethhdr	ethhdr;
+	struct hsr_tag	hsr_tag;
+} __attribute__((packed));
+
+
+struct hsr_supervision_tag {
+	__be16		path_and_HSR_ver;
+	__be16		sequence_nr;
+	__u8		HSR_TLV_Type;
+	__u8		HSR_TLV_Length;
+#ifdef CONFIG_NONSTANDARD_HSR
+	__be16		padding;
+#endif
+	unsigned char	MacAddressA[ETH_ALEN];
+} __attribute__((packed));
+
+
+struct hsr_dev_data {
+	struct net_device *dev;
+	struct list_head frame_db;
+};
+
+struct hsr_slave_data {
+	struct hsr_dev_data dev_data;
+	unsigned char orig_mac[ETH_ALEN];
+	int promisc;
+	int was_up;
+};
+
+struct hsr_priv {
+	struct list_head hsr_list;		/* List of hsr devices */
+	struct rcu_head rcu_head;
+	struct hsr_dev_data dev_data;
+	struct hsr_slave_data slave_data[2];
+	struct timer_list announce_timer;	/* Supervision frame dispatch */
+	int announce_count;
+	int online;
+	u16 sequence_nr;
+	spinlock_t seqlock;
+};
+
+extern const u8 hsr_multicast_addr[ETH_ALEN];
+
+void register_hsr_master(struct hsr_priv *hsr_priv);
+void unregister_hsr_master(struct hsr_priv *hsr_priv);
+
+void hsr_dev_setup(struct net_device *dev);
+int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *slave[2]);
+
+void hsr_check_announce(struct net_device *hsr_dev, struct net_device *slave1,
+						struct net_device *slave2);
+int is_hsr_master(struct net_device *dev);
+
+void skb_print(struct sk_buff *skb, const char *file, const int line);
+
+#endif /*  _HSR_PRIVATE_H */

-- 
Arvid Brodin
Enea Services Stockholm AB - since February 16 a part of Xdin in the Alten
Group. Soon we will be working under the common brand Xdin. Read more at
www.xdin.com.