can: add support of SAE J1939 protocol

SAE J1939 is the vehicle bus recommended practice used for communication
and diagnostics among vehicle components. Originating in the car and
heavy-duty truck industry in the United States, it is now widely used in
other parts of the world.

J1939, ISO 11783 and NMEA 2000 all share the same high level protocol.
SAE J1939 can be considered the replacement for the older SAE J1708 and
SAE J1587 specifications.
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Bastian Stender <bst@pengutronix.de>
Signed-off-by: Elenita Hinds <ecathinds@gmail.com>
Signed-off-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Kurt Van Dijck <dev.kurt@vandijck-laurijssen.be>
Signed-off-by: Maxime Jayat <maxime.jayat@mobile-devices.fr>
Signed-off-by: Robin van der Gracht <robin@protonic.nl>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Documentation/networking/index.rst

@@ -17,6 +17,7 @@ Contents:
    devlink-trap
    devlink-trap-netdevsim
    ieee802154
+   j1939
    kapi
    z8530book
    msg_zerocopy

MAINTAINERS

@@ -3669,6 +3669,16 @@ F:	include/uapi/linux/can/bcm.h
 F:	include/uapi/linux/can/raw.h
 F:	include/uapi/linux/can/gw.h
 
+CAN-J1939 NETWORK LAYER
+M:	Robin van der Gracht <robin@protonic.nl>
+M:	Oleksij Rempel <o.rempel@pengutronix.de>
+R:	Pengutronix Kernel Team <kernel@pengutronix.de>
+L:	linux-can@vger.kernel.org
+S:	Maintained
+F:	Documentation/networking/j1939.txt
+F:	net/can/j1939/
+F:	include/uapi/linux/can/j1939.h
+
 CAPABILITIES
 M:	Serge Hallyn <serge@hallyn.com>
 L:	linux-security-module@vger.kernel.org

include/linux/can/can-ml.h

@@ -60,6 +60,9 @@ struct can_dev_rcv_lists {
 
 struct can_ml_priv {
 	struct can_dev_rcv_lists dev_rcv_lists;
+#ifdef CAN_J1939
+	struct j1939_priv *j1939_priv;
+#endif
 };
 
 #endif /* CAN_ML_H */

include/uapi/linux/can/j1939.h

+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * j1939.h
+ *
+ * Copyright (c) 2010-2011 EIA Electronics
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _UAPI_CAN_J1939_H_
+#define _UAPI_CAN_J1939_H_
+
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/can.h>
+
+#define J1939_MAX_UNICAST_ADDR 0xfd
+#define J1939_IDLE_ADDR 0xfe
+#define J1939_NO_ADDR 0xff		/* == broadcast or no addr */
+#define J1939_NO_NAME 0
+#define J1939_PGN_REQUEST 0x0ea00		/* Request PG */
+#define J1939_PGN_ADDRESS_CLAIMED 0x0ee00	/* Address Claimed */
+#define J1939_PGN_ADDRESS_COMMANDED 0x0fed8	/* Commanded Address */
+#define J1939_PGN_PDU1_MAX 0x3ff00
+#define J1939_PGN_MAX 0x3ffff
+#define J1939_NO_PGN 0x40000
+
+/* J1939 Parameter Group Number
+ *
+ * bit 0-7	: PDU Specific (PS)
+ * bit 8-15	: PDU Format (PF)
+ * bit 16	: Data Page (DP)
+ * bit 17	: Reserved (R)
+ * bit 19-31	: set to zero
+ */
+typedef __u32 pgn_t;
+
+/* J1939 Priority
+ *
+ * bit 0-2	: Priority (P)
+ * bit 3-7	: set to zero
+ */
+typedef __u8 priority_t;
+
+/* J1939 NAME
+ *
+ * bit 0-20	: Identity Number
+ * bit 21-31	: Manufacturer Code
+ * bit 32-34	: ECU Instance
+ * bit 35-39	: Function Instance
+ * bit 40-47	: Function
+ * bit 48	: Reserved
+ * bit 49-55	: Vehicle System
+ * bit 56-59	: Vehicle System Instance
+ * bit 60-62	: Industry Group
+ * bit 63	: Arbitrary Address Capable
+ */
+typedef __u64 name_t;
+
+/* J1939 socket options */
+#define SOL_CAN_J1939 (SOL_CAN_BASE + CAN_J1939)
+enum {
+	SO_J1939_FILTER = 1,	/* set filters */
+	SO_J1939_PROMISC = 2,	/* set/clr promiscuous mode */
+	SO_J1939_SEND_PRIO = 3,
+	SO_J1939_ERRQUEUE = 4,
+};
+
+enum {
+	SCM_J1939_DEST_ADDR = 1,
+	SCM_J1939_DEST_NAME = 2,
+	SCM_J1939_PRIO = 3,
+	SCM_J1939_ERRQUEUE = 4,
+};
+
+enum {
+	J1939_NLA_PAD,
+	J1939_NLA_BYTES_ACKED,
+};
+
+enum {
+	J1939_EE_INFO_NONE,
+	J1939_EE_INFO_TX_ABORT,
+};
+
+struct j1939_filter {
+	name_t name;
+	name_t name_mask;
+	pgn_t pgn;
+	pgn_t pgn_mask;
+	__u8 addr;
+	__u8 addr_mask;
+};
+
+#define J1939_FILTER_MAX 512 /* maximum number of j1939_filter set via setsockopt() */
+
+#endif /* !_UAPI_CAN_J1939_H_ */

net/can/Kconfig

@@ -53,6 +53,8 @@ config CAN_GW
 	  They can be modified with AND/OR/XOR/SET operations as configured
 	  by the netlink configuration interface known e.g. from iptables.
 
+source "net/can/j1939/Kconfig"
+
 source "drivers/net/can/Kconfig"
 
 endif

net/can/Makefile

@@ -15,3 +15,5 @@ can-bcm-y		:= bcm.o
 
 obj-$(CONFIG_CAN_GW)	+= can-gw.o
 can-gw-y		:= gw.o
+
+obj-$(CONFIG_CAN_J1939)	+= j1939/

net/can/j1939/Kconfig

+# SPDX-License-Identifier: GPL-2.0
+#
+# SAE J1939 network layer core configuration
+#
+
+config CAN_J1939
+	tristate "SAE J1939"
+	depends on CAN
+	help
+	  SAE J1939
+	  Say Y to have in-kernel support for j1939 socket type. This
+	  allows communication according to SAE j1939.
+	  The relevant parts in kernel are
+	  SAE j1939-21 (datalink & transport protocol)
+	  & SAE j1939-81 (network management).

net/can/j1939/Makefile

+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_CAN_J1939) += can-j1939.o
+
+can-j1939-objs := \
+	address-claim.o \
+	bus.o \
+	main.o \
+	socket.o \
+	transport.o

net/can/j1939/address-claim.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2010-2011 EIA Electronics,
+//                         Kurt Van Dijck <kurt.van.dijck@eia.be>
+// Copyright (c) 2010-2011 EIA Electronics,
+//                         Pieter Beyens <pieter.beyens@eia.be>
+// Copyright (c) 2017-2019 Pengutronix,
+//                         Marc Kleine-Budde <kernel@pengutronix.de>
+// Copyright (c) 2017-2019 Pengutronix,
+//                         Oleksij Rempel <kernel@pengutronix.de>
+
+/* J1939 Address Claiming.
+ * Address Claiming in the kernel
+ * - keeps track of the AC states of ECU's,
+ * - resolves NAME<=>SA taking into account the AC states of ECU's.
+ *
+ * All Address Claim msgs (including host-originated msg) are processed
+ * at the receive path (a sent msg is always received again via CAN echo).
+ * As such, the processing of AC msgs is done in the order on which msgs
+ * are sent on the bus.
+ *
+ * This module doesn't send msgs itself (e.g. replies on Address Claims),
+ * this is the responsibility of a user space application or daemon.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+
+#include "j1939-priv.h"
+
+static inline name_t j1939_skb_to_name(const struct sk_buff *skb)
+{
+	return le64_to_cpup((__le64 *)skb->data);
+}
+
+static inline bool j1939_ac_msg_is_request(struct sk_buff *skb)
+{
+	struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
+	int req_pgn;
+
+	if (skb->len < 3 || skcb->addr.pgn != J1939_PGN_REQUEST)
+		return false;
+
+	req_pgn = skb->data[0] | (skb->data[1] << 8) | (skb->data[2] << 16);
+
+	return req_pgn == J1939_PGN_ADDRESS_CLAIMED;
+}
+
+static int j1939_ac_verify_outgoing(struct j1939_priv *priv,
+				    struct sk_buff *skb)
+{
+	struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
+
+	if (skb->len != 8) {
+		netdev_notice(priv->ndev, "tx address claim with dlc %i\n",
+			      skb->len);
+		return -EPROTO;
+	}
+
+	if (skcb->addr.src_name != j1939_skb_to_name(skb)) {
+		netdev_notice(priv->ndev, "tx address claim with different name\n");
+		return -EPROTO;
+	}
+
+	if (skcb->addr.sa == J1939_NO_ADDR) {
+		netdev_notice(priv->ndev, "tx address claim with broadcast sa\n");
+		return -EPROTO;
+	}
+
+	/* ac must always be a broadcast */
+	if (skcb->addr.dst_name || skcb->addr.da != J1939_NO_ADDR) {
+		netdev_notice(priv->ndev, "tx address claim with dest, not broadcast\n");
+		return -EPROTO;
+	}
+	return 0;
+}
+
+int j1939_ac_fixup(struct j1939_priv *priv, struct sk_buff *skb)
+{
+	struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
+	int ret;
+	u8 addr;
+
+	/* network mgmt: address claiming msgs */
+	if (skcb->addr.pgn == J1939_PGN_ADDRESS_CLAIMED) {
+		struct j1939_ecu *ecu;
+
+		ret = j1939_ac_verify_outgoing(priv, skb);
+		/* return both when failure & when successful */
+		if (ret < 0)
+			return ret;
+		ecu = j1939_ecu_get_by_name(priv, skcb->addr.src_name);
+		if (!ecu)
+			return -ENODEV;
+
+		if (ecu->addr != skcb->addr.sa)
+			/* hold further traffic for ecu, remove from parent */
+			j1939_ecu_unmap(ecu);
+		j1939_ecu_put(ecu);
+	} else if (skcb->addr.src_name) {
+		/* assign source address */
+		addr = j1939_name_to_addr(priv, skcb->addr.src_name);
+		if (!j1939_address_is_unicast(addr) &&
+		    !j1939_ac_msg_is_request(skb)) {
+			netdev_notice(priv->ndev, "tx drop: invalid sa for name 0x%016llx\n",
+				      skcb->addr.src_name);
+			return -EADDRNOTAVAIL;
+		}
+		skcb->addr.sa = addr;
+	}
+
+	/* assign destination address */
+	if (skcb->addr.dst_name) {
+		addr = j1939_name_to_addr(priv, skcb->addr.dst_name);
+		if (!j1939_address_is_unicast(addr)) {
+			netdev_notice(priv->ndev, "tx drop: invalid da for name 0x%016llx\n",
+				      skcb->addr.dst_name);
+			return -EADDRNOTAVAIL;
+		}
+		skcb->addr.da = addr;
+	}
+	return 0;
+}
+
+static void j1939_ac_process(struct j1939_priv *priv, struct sk_buff *skb)
+{
+	struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
+	struct j1939_ecu *ecu, *prev;
+	name_t name;
+
+	if (skb->len != 8) {
+		netdev_notice(priv->ndev, "rx address claim with wrong dlc %i\n",
+			      skb->len);
+		return;
+	}
+
+	name = j1939_skb_to_name(skb);
+	skcb->addr.src_name = name;
+	if (!name) {
+		netdev_notice(priv->ndev, "rx address claim without name\n");
+		return;
+	}
+
+	if (!j1939_address_is_valid(skcb->addr.sa)) {
+		netdev_notice(priv->ndev, "rx address claim with broadcast sa\n");
+		return;
+	}
+
+	write_lock_bh(&priv->lock);
+
+	/* Few words on the ECU ref counting:
+	 *
+	 * First we get an ECU handle, either with
+	 * j1939_ecu_get_by_name_locked() (increments the ref counter)
+	 * or j1939_ecu_create_locked() (initializes an ECU object
+	 * with a ref counter of 1).
+	 *
+	 * j1939_ecu_unmap_locked() will decrement the ref counter,
+	 * but only if the ECU was mapped before. So "ecu" still
+	 * belongs to us.
+	 *
+	 * j1939_ecu_timer_start() will increment the ref counter
+	 * before it starts the timer, so we can put the ecu when
+	 * leaving this function.
+	 */
+	ecu = j1939_ecu_get_by_name_locked(priv, name);
+	if (!ecu && j1939_address_is_unicast(skcb->addr.sa))
+		ecu = j1939_ecu_create_locked(priv, name);
+
+	if (IS_ERR_OR_NULL(ecu))
+		goto out_unlock_bh;
+
+	/* cancel pending (previous) address claim */
+	j1939_ecu_timer_cancel(ecu);
+
+	if (j1939_address_is_idle(skcb->addr.sa)) {
+		j1939_ecu_unmap_locked(ecu);
+		goto out_ecu_put;
+	}
+
+	/* save new addr */
+	if (ecu->addr != skcb->addr.sa)
+		j1939_ecu_unmap_locked(ecu);
+	ecu->addr = skcb->addr.sa;
+
+	prev = j1939_ecu_get_by_addr_locked(priv, skcb->addr.sa);
+	if (prev) {
+		if (ecu->name > prev->name) {
+			j1939_ecu_unmap_locked(ecu);
+			j1939_ecu_put(prev);
+			goto out_ecu_put;
+		} else {
+			/* kick prev if less or equal */
+			j1939_ecu_unmap_locked(prev);
+			j1939_ecu_put(prev);
+		}
+	}
+
+	j1939_ecu_timer_start(ecu);
+ out_ecu_put:
+	j1939_ecu_put(ecu);
+ out_unlock_bh:
+	write_unlock_bh(&priv->lock);
+}
+
+void j1939_ac_recv(struct j1939_priv *priv, struct sk_buff *skb)
+{
+	struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
+	struct j1939_ecu *ecu;
+
+	/* network mgmt */
+	if (skcb->addr.pgn == J1939_PGN_ADDRESS_CLAIMED) {
+		j1939_ac_process(priv, skb);
+	} else if (j1939_address_is_unicast(skcb->addr.sa)) {
+		/* assign source name */
+		ecu = j1939_ecu_get_by_addr(priv, skcb->addr.sa);
+		if (ecu) {
+			skcb->addr.src_name = ecu->name;
+			j1939_ecu_put(ecu);
+		}
+	}
+
+	/* assign destination name */
+	ecu = j1939_ecu_get_by_addr(priv, skcb->addr.da);
+	if (ecu) {
+		skcb->addr.dst_name = ecu->name;
+		j1939_ecu_put(ecu);
+	}
+}

net/can/j1939/bus.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2010-2011 EIA Electronics,
+//                         Kurt Van Dijck <kurt.van.dijck@eia.be>
+// Copyright (c) 2017-2019 Pengutronix,
+//                         Marc Kleine-Budde <kernel@pengutronix.de>
+// Copyright (c) 2017-2019 Pengutronix,
+//                         Oleksij Rempel <kernel@pengutronix.de>
+
+/* bus for j1939 remote devices
+ * Since rtnetlink, no real bus is used.
+ */
+
+#include <net/sock.h>
+
+#include "j1939-priv.h"
+
+static void __j1939_ecu_release(struct kref *kref)
+{
+	struct j1939_ecu *ecu = container_of(kref, struct j1939_ecu, kref);
+	struct j1939_priv *priv = ecu->priv;
+
+	list_del(&ecu->list);
+	kfree(ecu);
+	j1939_priv_put(priv);
+}
+
+void j1939_ecu_put(struct j1939_ecu *ecu)
+{
+	kref_put(&ecu->kref, __j1939_ecu_release);
+}
+
+static void j1939_ecu_get(struct j1939_ecu *ecu)
+{
+	kref_get(&ecu->kref);
+}
+
+static bool j1939_ecu_is_mapped_locked(struct j1939_ecu *ecu)
+{
+	struct j1939_priv *priv = ecu->priv;
+
+	lockdep_assert_held(&priv->lock);
+
+	return j1939_ecu_find_by_addr_locked(priv, ecu->addr) == ecu;
+}
+
+/* ECU device interface */
+/* map ECU to a bus address space */
+static void j1939_ecu_map_locked(struct j1939_ecu *ecu)
+{
+	struct j1939_priv *priv = ecu->priv;
+	struct j1939_addr_ent *ent;
+
+	lockdep_assert_held(&priv->lock);
+
+	if (!j1939_address_is_unicast(ecu->addr))
+		return;
+
+	ent = &priv->ents[ecu->addr];
+
+	if (ent->ecu) {
+		netdev_warn(priv->ndev, "Trying to map already mapped ECU, addr: 0x%02x, name: 0x%016llx. Skip it.\n",
+			    ecu->addr, ecu->name);
+		return;
+	}
+
+	j1939_ecu_get(ecu);
+	ent->ecu = ecu;
+	ent->nusers += ecu->nusers;
+}
+
+/* unmap ECU from a bus address space */
+void j1939_ecu_unmap_locked(struct j1939_ecu *ecu)
+{
+	struct j1939_priv *priv = ecu->priv;
+	struct j1939_addr_ent *ent;
+
+	lockdep_assert_held(&priv->lock);
+
+	if (!j1939_address_is_unicast(ecu->addr))
+		return;
+
+	if (!j1939_ecu_is_mapped_locked(ecu))
+		return;
+
+	ent = &priv->ents[ecu->addr];
+	ent->ecu = NULL;
+	ent->nusers -= ecu->nusers;
+	j1939_ecu_put(ecu);
+}
+
+void j1939_ecu_unmap(struct j1939_ecu *ecu)
+{
+	write_lock_bh(&ecu->priv->lock);
+	j1939_ecu_unmap_locked(ecu);
+	write_unlock_bh(&ecu->priv->lock);
+}
+
+void j1939_ecu_unmap_all(struct j1939_priv *priv)
+{
+	int i;
+
+	write_lock_bh(&priv->lock);
+	for (i = 0; i < ARRAY_SIZE(priv->ents); i++)
+		if (priv->ents[i].ecu)
+			j1939_ecu_unmap_locked(priv->ents[i].ecu);
+	write_unlock_bh(&priv->lock);
+}
+
+void j1939_ecu_timer_start(struct j1939_ecu *ecu)
+{
+	/* The ECU is held here and released in the
+	 * j1939_ecu_timer_handler() or j1939_ecu_timer_cancel().
+	 */
+	j1939_ecu_get(ecu);
+
+	/* Schedule timer in 250 msec to commit address change. */
+	hrtimer_start(&ecu->ac_timer, ms_to_ktime(250),
+		      HRTIMER_MODE_REL_SOFT);
+}
+
+void j1939_ecu_timer_cancel(struct j1939_ecu *ecu)
+{
+	if (hrtimer_cancel(&ecu->ac_timer))
+		j1939_ecu_put(ecu);
+}
+
+static enum hrtimer_restart j1939_ecu_timer_handler(struct hrtimer *hrtimer)
+{
+	struct j1939_ecu *ecu =
+		container_of(hrtimer, struct j1939_ecu, ac_timer);
+	struct j1939_priv *priv = ecu->priv;
+
+	write_lock_bh(&priv->lock);
+	/* TODO: can we test if ecu->addr is unicast before starting
+	 * the timer?
+	 */
+	j1939_ecu_map_locked(ecu);
+
+	/* The corresponding j1939_ecu_get() is in
+	 * j1939_ecu_timer_start().
+	 */
+	j1939_ecu_put(ecu);
+	write_unlock_bh(&priv->lock);
+
+	return HRTIMER_NORESTART;
+}
+
+struct j1939_ecu *j1939_ecu_create_locked(struct j1939_priv *priv, name_t name)
+{
+	struct j1939_ecu *ecu;
+
+	lockdep_assert_held(&priv->lock);
+
+	ecu = kzalloc(sizeof(*ecu), gfp_any());
+	if (!ecu)
+		return ERR_PTR(-ENOMEM);
+	kref_init(&ecu->kref);
+	ecu->addr = J1939_IDLE_ADDR;
+	ecu->name = name;
+
+	hrtimer_init(&ecu->ac_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
+	ecu->ac_timer.function = j1939_ecu_timer_handler;
+	INIT_LIST_HEAD(&ecu->list);
+
+	j1939_priv_get(priv);
+	ecu->priv = priv;
+	list_add_tail(&ecu->list, &priv->ecus);
+
+	return ecu;
+}
+
+struct j1939_ecu *j1939_ecu_find_by_addr_locked(struct j1939_priv *priv,
+						u8 addr)
+{
+	lockdep_assert_held(&priv->lock);
+
+	return priv->ents[addr].ecu;
+}
+
+struct j1939_ecu *j1939_ecu_get_by_addr_locked(struct j1939_priv *priv, u8 addr)
+{
+	struct j1939_ecu *ecu;
+
+	lockdep_assert_held(&priv->lock);
+
+	if (!j1939_address_is_unicast(addr))
+		return NULL;
+
+	ecu = j1939_ecu_find_by_addr_locked(priv, addr);
+	if (ecu)
+		j1939_ecu_get(ecu);
+
+	return ecu;
+}
+
+struct j1939_ecu *j1939_ecu_get_by_addr(struct j1939_priv *priv, u8 addr)
+{
+	struct j1939_ecu *ecu;
+
+	read_lock_bh(&priv->lock);
+	ecu = j1939_ecu_get_by_addr_locked(priv, addr);
+	read_unlock_bh(&priv->lock);
+
+	return ecu;
+}
+
+/* get pointer to ecu without increasing ref counter */
+static struct j1939_ecu *j1939_ecu_find_by_name_locked(struct j1939_priv *priv,
+						       name_t name)
+{
+	struct j1939_ecu *ecu;
+
+	lockdep_assert_held(&priv->lock);
+
+	list_for_each_entry(ecu, &priv->ecus, list) {
+		if (ecu->name == name)
+			return ecu;
+	}
+
+	return NULL;
+}
+
+struct j1939_ecu *j1939_ecu_get_by_name_locked(struct j1939_priv *priv,
+					       name_t name)
+{
+	struct j1939_ecu *ecu;
+
+	lockdep_assert_held(&priv->lock);
+
+	if (!name)
+		return NULL;
+
+	ecu = j1939_ecu_find_by_name_locked(priv, name);
+	if (ecu)
+		j1939_ecu_get(ecu);
+
+	return ecu;
+}
+
+struct j1939_ecu *j1939_ecu_get_by_name(struct j1939_priv *priv, name_t name)
+{
+	struct j1939_ecu *ecu;
+
+	read_lock_bh(&priv->lock);
+	ecu = j1939_ecu_get_by_name_locked(priv, name);
+	read_unlock_bh(&priv->lock);
+
+	return ecu;
+}
+
+u8 j1939_name_to_addr(struct j1939_priv *priv, name_t name)
+{
+	struct j1939_ecu *ecu;
+	int addr = J1939_IDLE_ADDR;
+
+	if (!name)
+		return J1939_NO_ADDR;
+
+	read_lock_bh(&priv->lock);
+	ecu = j1939_ecu_find_by_name_locked(priv, name);
+	if (ecu && j1939_ecu_is_mapped_locked(ecu))
+		/* ecu's SA is registered */
+		addr = ecu->addr;
+
+	read_unlock_bh(&priv->lock);
+
+	return addr;
+}
+
+/* TX addr/name accounting
+ * Transport protocol needs to know if a SA is local or not
+ * These functions originate from userspace manipulating sockets,
+ * so locking is straigforward
+ */
+
+int j1939_local_ecu_get(struct j1939_priv *priv, name_t name, u8 sa)
+{
+	struct j1939_ecu *ecu;
+	int err = 0;
+
+	write_lock_bh(&priv->lock);
+
+	if (j1939_address_is_unicast(sa))
+		priv->ents[sa].nusers++;
+
+	if (!name)
+		goto done;
+
+	ecu = j1939_ecu_get_by_name_locked(priv, name);
+	if (!ecu)
+		ecu = j1939_ecu_create_locked(priv, name);
+	err = PTR_ERR_OR_ZERO(ecu);
+	if (err)
+		goto done;
+
+	ecu->nusers++;
+	/* TODO: do we care if ecu->addr != sa? */
+	if (j1939_ecu_is_mapped_locked(ecu))
+		/* ecu's sa is active already */
+		priv->ents[ecu->addr].nusers++;
+
+ done:
+	write_unlock_bh(&priv->lock);
+
+	return err;
+}
+
+void j1939_local_ecu_put(struct j1939_priv *priv, name_t name, u8 sa)
+{
+	struct j1939_ecu *ecu;
+
+	write_lock_bh(&priv->lock);
+
+	if (j1939_address_is_unicast(sa))
+		priv->ents[sa].nusers--;
+
+	if (!name)
+		goto done;
+
+	ecu = j1939_ecu_find_by_name_locked(priv, name);
+	if (WARN_ON_ONCE(!ecu))
+		goto done;
+
+	ecu->nusers--;
+	/* TODO: do we care if ecu->addr != sa? */
+	if (j1939_ecu_is_mapped_locked(ecu))
+		/* ecu's sa is active already */
+		priv->ents[ecu->addr].nusers--;
+	j1939_ecu_put(ecu);
+
+ done:
+	write_unlock_bh(&priv->lock);
+}

net/can/j1939/j1939-priv.h

+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (c) 2010-2011 EIA Electronics,
+//                         Kurt Van Dijck <kurt.van.dijck@eia.be>
+// Copyright (c) 2017-2019 Pengutronix,
+//                         Marc Kleine-Budde <kernel@pengutronix.de>
+// Copyright (c) 2017-2019 Pengutronix,
+//                         Oleksij Rempel <kernel@pengutronix.de>
+
+#ifndef _J1939_PRIV_H_
+#define _J1939_PRIV_H_
+
+#include <linux/can/j1939.h>
+#include <net/sock.h>
+
+/* Timeout to receive the abort signal over loop back. In case CAN
+ * bus is open, the timeout should be triggered.
+ */
+#define J1939_XTP_ABORT_TIMEOUT_MS 500
+#define J1939_SIMPLE_ECHO_TIMEOUT_MS (10 * 1000)
+
+struct j1939_session;
+enum j1939_sk_errqueue_type {
+	J1939_ERRQUEUE_ACK,
+	J1939_ERRQUEUE_SCHED,
+	J1939_ERRQUEUE_ABORT,
+};
+
+/* j1939 devices */
+struct j1939_ecu {
+	struct list_head list;
+	name_t name;
+	u8 addr;
+
+	/* indicates that this ecu successfully claimed @sa as its address */
+	struct hrtimer ac_timer;
+	struct kref kref;
+	struct j1939_priv *priv;
+
+	/* count users, to help transport protocol decide for interaction */
+	int nusers;
+};
+
+struct j1939_priv {
+	struct list_head ecus;
+	/* local list entry in priv
+	 * These allow irq (& softirq) context lookups on j1939 devices
+	 * This approach (separate lists) is done as the other 2 alternatives
+	 * are not easier or even wrong
+	 * 1) using the pure kobject methods involves mutexes, which are not
+	 *    allowed in irq context.
+	 * 2) duplicating data structures would require a lot of synchronization
+	 *    code
+	 * usage:
+	 */
+
+	/* segments need a lock to protect the above list */
+	rwlock_t lock;
+
+	struct net_device *ndev;
+
+	/* list of 256 ecu ptrs, that cache the claimed addresses.
+	 * also protected by the above lock
+	 */
+	struct j1939_addr_ent {
+		struct j1939_ecu *ecu;
+		/* count users, to help transport protocol */
+		int nusers;
+	} ents[256];
+
+	struct kref kref;
+
+	/* List of active sessions to prevent start of conflicting
+	 * one.
+	 *
+	 * Do not start two sessions of same type, addresses and
+	 * direction.
+	 */
+	struct list_head active_session_list;
+
+	/* protects active_session_list */
+	spinlock_t active_session_list_lock;
+
+	unsigned int tp_max_packet_size;
+
+	/* lock for j1939_socks list */
+	spinlock_t j1939_socks_lock;
+	struct list_head j1939_socks;
+
+	struct kref rx_kref;
+};
+
+void j1939_ecu_put(struct j1939_ecu *ecu);
+
+/* keep the cache of what is local */
+int j1939_local_ecu_get(struct j1939_priv *priv, name_t name, u8 sa);
+void j1939_local_ecu_put(struct j1939_priv *priv, name_t name, u8 sa);
+
+static inline bool j1939_address_is_unicast(u8 addr)
+{
+	return addr <= J1939_MAX_UNICAST_ADDR;
+}
+
+static inline bool j1939_address_is_idle(u8 addr)
+{
+	return addr == J1939_IDLE_ADDR;
+}
+
+static inline bool j1939_address_is_valid(u8 addr)
+{
+	return addr != J1939_NO_ADDR;
+}
+
+static inline bool j1939_pgn_is_pdu1(pgn_t pgn)
+{
+	/* ignore dp & res bits for this */
+	return (pgn & 0xff00) < 0xf000;
+}
+
+/* utility to correctly unmap an ECU */
+void j1939_ecu_unmap_locked(struct j1939_ecu *ecu);
+void j1939_ecu_unmap(struct j1939_ecu *ecu);
+
+u8 j1939_name_to_addr(struct j1939_priv *priv, name_t name);
+struct j1939_ecu *j1939_ecu_find_by_addr_locked(struct j1939_priv *priv,
+						u8 addr);
+struct j1939_ecu *j1939_ecu_get_by_addr(struct j1939_priv *priv, u8 addr);
+struct j1939_ecu *j1939_ecu_get_by_addr_locked(struct j1939_priv *priv,
+					       u8 addr);
+struct j1939_ecu *j1939_ecu_get_by_name(struct j1939_priv *priv, name_t name);
+struct j1939_ecu *j1939_ecu_get_by_name_locked(struct j1939_priv *priv,
+					       name_t name);
+
+enum j1939_transfer_type {
+	J1939_TP,
+	J1939_ETP,
+	J1939_SIMPLE,
+};
+
+struct j1939_addr {
+	name_t src_name;
+	name_t dst_name;
+	pgn_t pgn;
+
+	u8 sa;
+	u8 da;
+
+	u8 type;
+};
+
+/* control buffer of the sk_buff */
+struct j1939_sk_buff_cb {
+	/* Offset in bytes within one ETP session */
+	u32 offset;
+
+	/* for tx, MSG_SYN will be used to sync on sockets */
+	u32 msg_flags;
+	u32 tskey;
+
+	struct j1939_addr addr;
+
+	/* Flags for quick lookups during skb processing.
+	 * These are set in the receive path only.
+	 */
+#define J1939_ECU_LOCAL_SRC BIT(0)
+#define J1939_ECU_LOCAL_DST BIT(1)
+	u8 flags;
+
+	priority_t priority;
+};
+
+static inline
+struct j1939_sk_buff_cb *j1939_skb_to_cb(const struct sk_buff *skb)
+{
+	BUILD_BUG_ON(sizeof(struct j1939_sk_buff_cb) > sizeof(skb->cb));
+
+	return (struct j1939_sk_buff_cb *)skb->cb;
+}
+
+int j1939_send_one(struct j1939_priv *priv, struct sk_buff *skb);
+void j1939_sk_recv(struct j1939_priv *priv, struct sk_buff *skb);
+bool j1939_sk_recv_match(struct j1939_priv *priv,
+			 struct j1939_sk_buff_cb *skcb);
+void j1939_sk_send_loop_abort(struct sock *sk, int err);
+void j1939_sk_errqueue(struct j1939_session *session,
+		       enum j1939_sk_errqueue_type type);
+void j1939_sk_queue_activate_next(struct j1939_session *session);
+
+/* stack entries */
+struct j1939_session *j1939_tp_send(struct j1939_priv *priv,
+				    struct sk_buff *skb, size_t size);
+int j1939_tp_recv(struct j1939_priv *priv, struct sk_buff *skb);
+int j1939_ac_fixup(struct j1939_priv *priv, struct sk_buff *skb);
+void j1939_ac_recv(struct j1939_priv *priv, struct sk_buff *skb);
+void j1939_simple_recv(struct j1939_priv *priv, struct sk_buff *skb);
+
+/* network management */
+struct j1939_ecu *j1939_ecu_create_locked(struct j1939_priv *priv, name_t name);
+
+void j1939_ecu_timer_start(struct j1939_ecu *ecu);
+void j1939_ecu_timer_cancel(struct j1939_ecu *ecu);
+void j1939_ecu_unmap_all(struct j1939_priv *priv);
+
+struct j1939_priv *j1939_netdev_start(struct net_device *ndev);
+void j1939_netdev_stop(struct j1939_priv *priv);
+
+void j1939_priv_put(struct j1939_priv *priv);
+void j1939_priv_get(struct j1939_priv *priv);
+
+/* notify/alert all j1939 sockets bound to ifindex */
+void j1939_sk_netdev_event_netdown(struct j1939_priv *priv);
+int j1939_cancel_active_session(struct j1939_priv *priv, struct sock *sk);
+void j1939_tp_init(struct j1939_priv *priv);
+
+/* decrement pending skb for a j1939 socket */
+void j1939_sock_pending_del(struct sock *sk);
+
+enum j1939_session_state {
+	J1939_SESSION_NEW,
+	J1939_SESSION_ACTIVE,
+	/* waiting for abort signal on the bus */
+	J1939_SESSION_WAITING_ABORT,
+	J1939_SESSION_ACTIVE_MAX,
+	J1939_SESSION_DONE,
+};
+
+struct j1939_session {
+	struct j1939_priv *priv;
+	struct list_head active_session_list_entry;
+	struct list_head sk_session_queue_entry;
+	struct kref kref;
+	struct sock *sk;
+
+	/* ifindex, src, dst, pgn define the session block
+	 * the are _never_ modified after insertion in the list
+	 * this decreases locking problems a _lot_
+	 */
+	struct j1939_sk_buff_cb skcb;
+	struct sk_buff_head skb_queue;
+
+	/* all tx related stuff (last_txcmd, pkt.tx)
+	 * is protected (modified only) with the txtimer hrtimer
+	 * 'total' & 'block' are never changed,
+	 * last_cmd, last & block are protected by ->lock
+	 * this means that the tx may run after cts is received that should
+	 * have stopped tx, but this time discrepancy is never avoided anyhow
+	 */
+	u8 last_cmd, last_txcmd;
+	bool transmission;
+	bool extd;
+	/* Total message size, number of bytes */
+	unsigned int total_message_size;
+	/* Total number of bytes queue from socket to the session */
+	unsigned int total_queued_size;
+	unsigned int tx_retry;
+
+	int err;
+	u32 tskey;
+	enum j1939_session_state state;
+
+	/* Packets counters for a (extended) transfer session. The packet is
+	 * maximal of 7 bytes.
+	 */
+	struct {
+		/* total - total number of packets for this session */
+		unsigned int total;
+		/* last - last packet of a transfer block after which
+		 * responder should send ETP.CM_CTS and originator
+		 * ETP.CM_DPO
+		 */
+		unsigned int last;
+		/* tx - number of packets send by originator node.
+		 * this counter can be set back if responder node
+		 * didn't received all packets send by originator.
+		 */
+		unsigned int tx;
+		unsigned int tx_acked;
+		/* rx - number of packets received */
+		unsigned int rx;
+		/* block - amount of packets expected in one block */
+		unsigned int block;
+		/* dpo - ETP.CM_DPO, Data Packet Offset */
+		unsigned int dpo;
+	} pkt;
+	struct hrtimer txtimer, rxtimer;
+};
+
+struct j1939_sock {
+	struct sock sk; /* must be first to skip with memset */
+	struct j1939_priv *priv;
+	struct list_head list;
+
+#define J1939_SOCK_BOUND BIT(0)
+#define J1939_SOCK_CONNECTED BIT(1)
+#define J1939_SOCK_PROMISC BIT(2)
+#define J1939_SOCK_ERRQUEUE BIT(3)
+	int state;
+
+	int ifindex;
+	struct j1939_addr addr;
+	struct j1939_filter *filters;
+	int nfilters;
+	pgn_t pgn_rx_filter;
+
+	/* j1939 may emit equal PGN (!= equal CAN-id's) out of order
+	 * when transport protocol comes in.
+	 * To allow emitting in order, keep a 'pending' nr. of packets
+	 */
+	atomic_t skb_pending;
+	wait_queue_head_t waitq;
+
+	/* lock for the sk_session_queue list */
+	spinlock_t sk_session_queue_lock;
+	struct list_head sk_session_queue;
+};
+
+static inline struct j1939_sock *j1939_sk(const struct sock *sk)
+{
+	return container_of(sk, struct j1939_sock, sk);
+}
+
+void j1939_session_get(struct j1939_session *session);
+void j1939_session_put(struct j1939_session *session);
+void j1939_session_skb_queue(struct j1939_session *session,
+			     struct sk_buff *skb);
+int j1939_session_activate(struct j1939_session *session);
+void j1939_tp_schedule_txtimer(struct j1939_session *session, int msec);
+void j1939_session_timers_cancel(struct j1939_session *session);
+
+#define J1939_MAX_TP_PACKET_SIZE (7 * 0xff)
+#define J1939_MAX_ETP_PACKET_SIZE (7 * 0x00ffffff)
+
+#define J1939_REGULAR 0
+#define J1939_EXTENDED 1
+
+/* CAN protocol */
+extern const struct can_proto j1939_can_proto;
+
+#endif /* _J1939_PRIV_H_ */

net/can/j1939/main.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2010-2011 EIA Electronics,
+//                         Pieter Beyens <pieter.beyens@eia.be>
+// Copyright (c) 2010-2011 EIA Electronics,
+//                         Kurt Van Dijck <kurt.van.dijck@eia.be>
+// Copyright (c) 2018 Protonic,
+//                         Robin van der Gracht <robin@protonic.nl>
+// Copyright (c) 2017-2019 Pengutronix,
+//                         Marc Kleine-Budde <kernel@pengutronix.de>
+// Copyright (c) 2017-2019 Pengutronix,
+//                         Oleksij Rempel <kernel@pengutronix.de>
+
+/* Core of can-j1939 that links j1939 to CAN. */
+
+#include <linux/can/can-ml.h>
+#include <linux/can/core.h>
+#include <linux/can/skb.h>
+#include <linux/if_arp.h>
+#include <linux/module.h>
+
+#include "j1939-priv.h"
+
+MODULE_DESCRIPTION("PF_CAN SAE J1939");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("EIA Electronics (Kurt Van Dijck & Pieter Beyens)");
+MODULE_ALIAS("can-proto-" __stringify(CAN_J1939));
+
+/* LOWLEVEL CAN interface */
+
+/* CAN_HDR: #bytes before can_frame data part */
+#define J1939_CAN_HDR (offsetof(struct can_frame, data))
+
+/* CAN_FTR: #bytes beyond data part */
+#define J1939_CAN_FTR (sizeof(struct can_frame) - J1939_CAN_HDR - \
+		 sizeof(((struct can_frame *)0)->data))
+
+/* lowest layer */
+static void j1939_can_recv(struct sk_buff *iskb, void *data)
+{
+	struct j1939_priv *priv = data;
+	struct sk_buff *skb;
+	struct j1939_sk_buff_cb *skcb, *iskcb;
+	struct can_frame *cf;
+
+	/* create a copy of the skb
+	 * j1939 only delivers the real data bytes,
+	 * the header goes into sockaddr.
+	 * j1939 may not touch the incoming skb in such way
+	 */
+	skb = skb_clone(iskb, GFP_ATOMIC);
+	if (!skb)
+		return;
+
+	can_skb_set_owner(skb, iskb->sk);
+
+	/* get a pointer to the header of the skb
+	 * the skb payload (pointer) is moved, so that the next skb_data
+	 * returns the actual payload
+	 */
+	cf = (void *)skb->data;
+	skb_pull(skb, J1939_CAN_HDR);
+
+	/* fix length, set to dlc, with 8 maximum */
+	skb_trim(skb, min_t(uint8_t, cf->can_dlc, 8));
+
+	/* set addr */
+	skcb = j1939_skb_to_cb(skb);
+	memset(skcb, 0, sizeof(*skcb));
+
+	iskcb = j1939_skb_to_cb(iskb);
+	skcb->tskey = iskcb->tskey;
+	skcb->priority = (cf->can_id >> 26) & 0x7;
+	skcb->addr.sa = cf->can_id;
+	skcb->addr.pgn = (cf->can_id >> 8) & J1939_PGN_MAX;
+	/* set default message type */
+	skcb->addr.type = J1939_TP;
+	if (j1939_pgn_is_pdu1(skcb->addr.pgn)) {
+		/* Type 1: with destination address */
+		skcb->addr.da = skcb->addr.pgn;
+		/* normalize pgn: strip dst address */
+		skcb->addr.pgn &= 0x3ff00;
+	} else {
+		/* set broadcast address */
+		skcb->addr.da = J1939_NO_ADDR;
+	}
+
+	/* update localflags */
+	read_lock_bh(&priv->lock);
+	if (j1939_address_is_unicast(skcb->addr.sa) &&
+	    priv->ents[skcb->addr.sa].nusers)
+		skcb->flags |= J1939_ECU_LOCAL_SRC;
+	if (j1939_address_is_unicast(skcb->addr.da) &&
+	    priv->ents[skcb->addr.da].nusers)
+		skcb->flags |= J1939_ECU_LOCAL_DST;
+	read_unlock_bh(&priv->lock);
+
+	/* deliver into the j1939 stack ... */
+	j1939_ac_recv(priv, skb);
+
+	if (j1939_tp_recv(priv, skb))
+		/* this means the transport layer processed the message */
+		goto done;
+
+	j1939_simple_recv(priv, skb);
+	j1939_sk_recv(priv, skb);
+ done:
+	kfree_skb(skb);
+}
+
+/* NETDEV MANAGEMENT */
+
+/* values for can_rx_(un)register */
+#define J1939_CAN_ID CAN_EFF_FLAG
+#define J1939_CAN_MASK (CAN_EFF_FLAG | CAN_RTR_FLAG)
+
+static DEFINE_SPINLOCK(j1939_netdev_lock);
+
+static struct j1939_priv *j1939_priv_create(struct net_device *ndev)
+{
+	struct j1939_priv *priv;
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return NULL;
+
+	rwlock_init(&priv->lock);
+	INIT_LIST_HEAD(&priv->ecus);
+	priv->ndev = ndev;
+	kref_init(&priv->kref);
+	kref_init(&priv->rx_kref);
+	dev_hold(ndev);
+
+	netdev_dbg(priv->ndev, "%s : 0x%p\n", __func__, priv);
+
+	return priv;
+}
+
+static inline void j1939_priv_set(struct net_device *ndev,
+				  struct j1939_priv *priv)
+{
+	struct can_ml_priv *can_ml_priv = ndev->ml_priv;
+
+	can_ml_priv->j1939_priv = priv;
+}
+
+static void __j1939_priv_release(struct kref *kref)
+{
+	struct j1939_priv *priv = container_of(kref, struct j1939_priv, kref);
+	struct net_device *ndev = priv->ndev;
+
+	netdev_dbg(priv->ndev, "%s: 0x%p\n", __func__, priv);
+
+	dev_put(ndev);
+	kfree(priv);
+}
+
+void j1939_priv_put(struct j1939_priv *priv)
+{
+	kref_put(&priv->kref, __j1939_priv_release);
+}
+
+void j1939_priv_get(struct j1939_priv *priv)
+{
+	kref_get(&priv->kref);
+}
+
+static int j1939_can_rx_register(struct j1939_priv *priv)
+{
+	struct net_device *ndev = priv->ndev;
+	int ret;
+
+	j1939_priv_get(priv);
+	ret = can_rx_register(dev_net(ndev), ndev, J1939_CAN_ID, J1939_CAN_MASK,
+			      j1939_can_recv, priv, "j1939", NULL);
+	if (ret < 0) {
+		j1939_priv_put(priv);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void j1939_can_rx_unregister(struct j1939_priv *priv)
+{
+	struct net_device *ndev = priv->ndev;
+
+	can_rx_unregister(dev_net(ndev), ndev, J1939_CAN_ID, J1939_CAN_MASK,
+			  j1939_can_recv, priv);
+
+	j1939_priv_put(priv);
+}
+
+static void __j1939_rx_release(struct kref *kref)
+	__releases(&j1939_netdev_lock)
+{
+	struct j1939_priv *priv = container_of(kref, struct j1939_priv,
+					       rx_kref);
+
+	j1939_can_rx_unregister(priv);
+	j1939_ecu_unmap_all(priv);
+	j1939_priv_set(priv->ndev, NULL);
+	spin_unlock(&j1939_netdev_lock);
+}
+
+/* get pointer to priv without increasing ref counter */
+static inline struct j1939_priv *j1939_ndev_to_priv(struct net_device *ndev)
+{
+	struct can_ml_priv *can_ml_priv = ndev->ml_priv;
+
+	return can_ml_priv->j1939_priv;
+}
+
+static struct j1939_priv *j1939_priv_get_by_ndev_locked(struct net_device *ndev)
+{
+	struct j1939_priv *priv;
+
+	lockdep_assert_held(&j1939_netdev_lock);
+
+	if (ndev->type != ARPHRD_CAN)
+		return NULL;
+
+	priv = j1939_ndev_to_priv(ndev);
+	if (priv)
+		j1939_priv_get(priv);
+
+	return priv;
+}
+
+static struct j1939_priv *j1939_priv_get_by_ndev(struct net_device *ndev)
+{
+	struct j1939_priv *priv;
+
+	spin_lock(&j1939_netdev_lock);
+	priv = j1939_priv_get_by_ndev_locked(ndev);
+	spin_unlock(&j1939_netdev_lock);
+
+	return priv;
+}
+
+struct j1939_priv *j1939_netdev_start(struct net_device *ndev)
+{
+	struct j1939_priv *priv, *priv_new;
+	int ret;
+
+	priv = j1939_priv_get_by_ndev(ndev);
+	if (priv) {
+		kref_get(&priv->rx_kref);
+		return priv;
+	}
+
+	priv = j1939_priv_create(ndev);
+	if (!priv)
+		return ERR_PTR(-ENOMEM);
+
+	j1939_tp_init(priv);
+	spin_lock_init(&priv->j1939_socks_lock);
+	INIT_LIST_HEAD(&priv->j1939_socks);
+
+	spin_lock(&j1939_netdev_lock);
+	priv_new = j1939_priv_get_by_ndev_locked(ndev);
+	if (priv_new) {
+		/* Someone was faster than us, use their priv and roll
+		 * back our's.
+		 */
+		spin_unlock(&j1939_netdev_lock);
+		dev_put(ndev);
+		kfree(priv);
+		kref_get(&priv_new->rx_kref);
+		return priv_new;
+	}
+	j1939_priv_set(ndev, priv);
+	spin_unlock(&j1939_netdev_lock);
+
+	ret = j1939_can_rx_register(priv);
+	if (ret < 0)
+		goto out_priv_put;
+
+	return priv;
+
+ out_priv_put:
+	j1939_priv_set(ndev, NULL);
+	dev_put(ndev);
+	kfree(priv);
+
+	return ERR_PTR(ret);
+}
+
+void j1939_netdev_stop(struct j1939_priv *priv)
+{
+	kref_put_lock(&priv->rx_kref, __j1939_rx_release, &j1939_netdev_lock);
+	j1939_priv_put(priv);
+}
+
+int j1939_send_one(struct j1939_priv *priv, struct sk_buff *skb)
+{
+	int ret, dlc;
+	canid_t canid;
+	struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
+	struct can_frame *cf;
+
+	/* apply sanity checks */
+	if (j1939_pgn_is_pdu1(skcb->addr.pgn))
+		skcb->addr.pgn &= J1939_PGN_PDU1_MAX;
+	else
+		skcb->addr.pgn &= J1939_PGN_MAX;
+
+	if (skcb->priority > 7)
+		skcb->priority = 6;
+
+	ret = j1939_ac_fixup(priv, skb);
+	if (unlikely(ret))
+		goto failed;
+	dlc = skb->len;
+
+	/* re-claim the CAN_HDR from the SKB */
+	cf = skb_push(skb, J1939_CAN_HDR);
+
+	/* make it a full can frame again */
+	skb_put(skb, J1939_CAN_FTR + (8 - dlc));
+
+	canid = CAN_EFF_FLAG |
+		(skcb->priority << 26) |
+		(skcb->addr.pgn << 8) |
+		skcb->addr.sa;
+	if (j1939_pgn_is_pdu1(skcb->addr.pgn))
+		canid |= skcb->addr.da << 8;
+
+	cf->can_id = canid;
+	cf->can_dlc = dlc;
+
+	return can_send(skb, 1);
+
+ failed:
+	kfree_skb(skb);
+	return ret;
+}
+
+static int j1939_netdev_notify(struct notifier_block *nb,
+			       unsigned long msg, void *data)
+{
+	struct net_device *ndev = netdev_notifier_info_to_dev(data);
+	struct j1939_priv *priv;
+
+	priv = j1939_priv_get_by_ndev(ndev);
+	if (!priv)
+		goto notify_done;
+
+	if (ndev->type != ARPHRD_CAN)
+		goto notify_put;
+
+	switch (msg) {
+	case NETDEV_DOWN:
+		j1939_cancel_active_session(priv, NULL);
+		j1939_sk_netdev_event_netdown(priv);
+		j1939_ecu_unmap_all(priv);
+		break;
+	}
+
+notify_put:
+	j1939_priv_put(priv);
+
+notify_done:
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block j1939_netdev_notifier = {
+	.notifier_call = j1939_netdev_notify,
+};
+
+/* MODULE interface */
+static __init int j1939_module_init(void)
+{
+	int ret;
+
+	pr_info("can: SAE J1939\n");
+
+	ret = register_netdevice_notifier(&j1939_netdev_notifier);
+	if (ret)
+		goto fail_notifier;
+
+	ret = can_proto_register(&j1939_can_proto);
+	if (ret < 0) {
+		pr_err("can: registration of j1939 protocol failed\n");
+		goto fail_sk;
+	}
+
+	return 0;
+
+ fail_sk:
+	unregister_netdevice_notifier(&j1939_netdev_notifier);
+ fail_notifier:
+	return ret;
+}
+
+static __exit void j1939_module_exit(void)
+{
+	can_proto_unregister(&j1939_can_proto);
+
+	unregister_netdevice_notifier(&j1939_netdev_notifier);
+}
+
+module_init(j1939_module_init);
+module_exit(j1939_module_exit);