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Subject: Re: [PATCH v5 1/6] net: lorawan: Add LoRaWAN socket module
To:     Jian-Hong Pan <starnight@g.ncu.edu.tw>
Cc:     "David S . Miller" <davem@davemloft.net>,
        Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
        linux-lpwan@lists.infradead.org, netdev@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Marcel Holtmann <marcel@holtmann.org>,
        Dollar Chen <dollar.chen@wtmec.com>,
        Ken Yu <ken.yu@rakwireless.com>, linux-wpan@vger.kernel.org,
        Ben Whitten <ben.whitten@lairdtech.com>
References: <CAC=mGziyi1ierhg++SUcHMrq1JQ0vH4gZCKUZgchzb8aD1Rv5Q@mail.gmail.com>
 <20181216101858.9585-2-starnight@g.ncu.edu.tw>
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Organization: SUSE Linux GmbH
Message-ID: <b1eb9451-cb15-3fc7-f95e-3100cf715ef6@suse.de>
Date:   Sat, 29 Dec 2018 08:27:09 +0100
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Hi Jian-Hong,

Am 16.12.18 um 11:18 schrieb Jian-Hong Pan:
> This patch adds a new address/protocol family for LoRaWAN network.
> It also implements the the functions and maps to Datagram socket for
> LoRaWAN unconfirmed data messages.
> 
> Signed-off-by: Jian-Hong Pan <starnight@g.ncu.edu.tw>
[...]
>  include/linux/lora/lorawan_netdev.h |  52 +++
>  net/lorawan/Kconfig                 |  10 +
>  net/lorawan/Makefile                |   2 +
>  net/lorawan/socket.c                | 686 ++++++++++++++++++++++++++++
>  4 files changed, 750 insertions(+)
>  create mode 100644 include/linux/lora/lorawan_netdev.h
>  create mode 100644 net/lorawan/Kconfig
>  create mode 100644 net/lorawan/Makefile
>  create mode 100644 net/lorawan/socket.c

I'm not 100% happy with this yet, but to decouple it from the soft-MAC
discussion (patches 2-6/6) and to allow reuse by Ben, I've staged it in
linux-lora.git.

We can clean it up with incremental patches there (and squash later).

> 
> diff --git a/include/linux/lora/lorawan_netdev.h b/include/linux/lora/lorawan_netdev.h
> new file mode 100644
> index 000000000000..5bffb5164f95
> --- /dev/null
> +++ b/include/linux/lora/lorawan_netdev.h
> @@ -0,0 +1,52 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later OR BSD-3-Clause */

Is there any practical reason you dual-license your code? My LoRa code
is only GPL - should I reconsider that?

> +/*-

I assume the dash is a typo?

> + * LoRaWAN stack related definitions
> + *
> + * Copyright (c) 2018 Jian-Hong, Pan <starnight@g.ncu.edu.tw>
> + *

Leftover white line from old license header?

> + */
> +
> +#ifndef __LORAWAN_NET_DEVICE_H__
> +#define __LORAWAN_NET_DEVICE_H__
> +
> +enum {
> +	LRW_ADDR_APPEUI,
> +	LRW_ADDR_DEVEUI,
> +	LRW_ADDR_DEVADDR,
> +};
> +
> +struct lrw_addr_in {
> +	int addr_type;
> +	union {
> +		u64 app_eui;
> +		u64 dev_eui;

In my RFC and in linux-lora.git I have a lora_eui typedef - any reason
you're not using it here?

> +		u32 devaddr;
> +	};
> +};
> +
> +struct sockaddr_lorawan {
> +	sa_family_t family; /* AF_LORAWAN */
> +	struct lrw_addr_in addr_in;
> +};
> +
> +/**
> + * lrw_mac_cb - This structure holds the control buffer (cb) of sk_buff
> + *
> + * @devaddr:	the LoRaWAN device address of this LoRaWAN hardware
> + */
> +struct lrw_mac_cb {
> +	u32 devaddr;
> +};
> +
> +/**
> + * lrw_get_mac_cb - Get the LoRaWAN MAC control buffer of the sk_buff
> + * @skb:	the exchanging sk_buff
> + *
> + * Return:	the pointer of LoRaWAN MAC control buffer
> + */
> +static inline struct lrw_mac_cb *lrw_get_mac_cb(struct sk_buff *skb)
> +{
> +	return (struct lrw_mac_cb *)skb->cb;
> +}

For LoRa I have a separate lora/skb.h - suggest to split this off into
its own header consistently.

> +
> +#endif
> diff --git a/net/lorawan/Kconfig b/net/lorawan/Kconfig
> new file mode 100644
> index 000000000000..bf6c9b77573b
> --- /dev/null
> +++ b/net/lorawan/Kconfig
> @@ -0,0 +1,10 @@
> +config LORAWAN
> +	tristate "LoRaWAN Network support"

The N in LoRaWAN is already for Network. :)

> +	help
> +	  LoRaWAN defines low data rate, low power and long range wireless
> +	  wide area networks. It was designed to organize networks of automation
> +	  devices, such as sensors, switches and actuators. It can operate
> +	  multiple kilometers wide.

The missing information here to distinguish it from LoRa would be that
it's a client/server technology centered around gateways. In particular
gateways that anyone can run, distinguishing it from (Sigfox or) NB-IoT.

> +
> +	  Say Y here to compile LoRaWAN support into the kernel or say M to
> +	  compile it as a module.
> diff --git a/net/lorawan/Makefile b/net/lorawan/Makefile
> new file mode 100644
> index 000000000000..8c923ca6541a
> --- /dev/null
> +++ b/net/lorawan/Makefile
> @@ -0,0 +1,2 @@
> +obj-$(CONFIG_LORAWAN)	+= lorawan.o
> +lorawan-objs		:= socket.o

Both Kconfig and Makefile are not integrated into net/ here. That
happens only in 6/6.

> diff --git a/net/lorawan/socket.c b/net/lorawan/socket.c
> new file mode 100644
> index 000000000000..7ef106b877ca
> --- /dev/null
> +++ b/net/lorawan/socket.c
> @@ -0,0 +1,686 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later OR BSD-3-Clause
> +/*-

?

> + * LoRaWAN stack related definitions
> + *
> + * Copyright (c) 2018 Jian-Hong, Pan <starnight@g.ncu.edu.tw>
> + *

?

> + */
> +
> +#define	LORAWAN_MODULE_NAME	"lorawan"
> +
> +#define	pr_fmt(fmt)		LORAWAN_MODULE_NAME ": " fmt
> +
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/list.h>
> +#include <linux/net.h>
> +#include <linux/if_arp.h>
> +#include <linux/termios.h>		/* For TIOCOUTQ/INQ */
> +#include <net/sock.h>
> +#include <linux/lora/lorawan_netdev.h>

Please sort headers alphabetically.

> +
> +/**
> + * dgram_sock - This structure holds the states of Datagram socket
> + *
> + * @sk:			network layer representation of the socket
> + *			sk must be the first member of dgram_sock

Might that sentence be more useful as inline comment below?

> + * @src_devaddr:	the LoRaWAN device address for this connection
> + * @bound:		this socket is bound or not
> + * @connected:		this socket is connected to the destination or not
> + * @want_ack:		this socket needs to ack for the connection or not

Doesn't exist below?

> + */
> +struct dgram_sock {
> +	struct sock sk;
> +	u32 src_devaddr;
> +
> +	u8 bound:1;
> +	u8 connected:1;
> +};
> +
> +static HLIST_HEAD(dgram_head);
> +static DEFINE_RWLOCK(dgram_lock);
> +
> +static struct dgram_sock *
> +dgram_sk(const struct sock *sk)
> +{
> +	return container_of(sk, struct dgram_sock, sk);
> +}
> +
> +static struct net_device *
> +lrw_get_dev_by_addr(struct net *net, u32 devaddr)
> +{
> +	__be32 be_addr = cpu_to_be32(devaddr);
> +	struct net_device *ndev = NULL;
> +
> +	rcu_read_lock();
> +	ndev = dev_getbyhwaddr_rcu(net, ARPHRD_LORAWAN, (char *)&be_addr);
> +	if (ndev)
> +		dev_hold(ndev);
> +	rcu_read_unlock();
> +
> +	return ndev;
> +}
> +
> +static int
> +dgram_init(struct sock *sk)
> +{
> +	return 0;
> +}
> +
> +static void
> +dgram_close(struct sock *sk, long timeout)
> +{
> +	sk_common_release(sk);
> +}
> +
> +static int
> +dgram_bind(struct sock *sk, struct sockaddr *uaddr, int len)
> +{
> +	struct sockaddr_lorawan *addr = (struct sockaddr_lorawan *)uaddr;
> +	struct dgram_sock *ro = dgram_sk(sk);
> +	struct net_device *ndev;
> +	int ret;
> +
> +	lock_sock(sk);
> +	ro->bound = 0;
> +
> +	ret = -EINVAL;
> +	if (len < sizeof(*addr))
> +		goto dgram_bind_end;
> +
> +	if (addr->family != AF_LORAWAN)
> +		goto dgram_bind_end;
> +
> +	if (addr->addr_in.addr_type != LRW_ADDR_DEVADDR)
> +		goto dgram_bind_end;
> +
> +	pr_debug("%s: bind address %X\n", __func__, addr->addr_in.devaddr);
> +	ndev = lrw_get_dev_by_addr(sock_net(sk), addr->addr_in.devaddr);
> +	if (!ndev) {
> +		ret = -ENODEV;
> +		goto dgram_bind_end;
> +	}
> +	netdev_dbg(ndev, "%s: get ndev\n", __func__);
> +
> +	if (ndev->type != ARPHRD_LORAWAN) {
> +		ret = -ENODEV;
> +		goto dgram_bind_end;

This is leaking ndev.

> +	}
> +
> +	ro->src_devaddr = addr->addr_in.devaddr;
> +	ro->bound = 1;
> +	ret = 0;
> +	dev_put(ndev);
> +	pr_debug("%s: bound address %X\n", __func__, ro->src_devaddr);
> +
> +dgram_bind_end:
> +	release_sock(sk);
> +	return ret;
> +}
> +
> +static int
> +lrw_dev_hard_header(struct sk_buff *skb, struct net_device *ndev,
> +		    const u32 src_devaddr, size_t len)
> +{
> +	/* TODO: Prepare the LoRaWAN sending header here */

I wonder, is your idea that you would always write headers here but have
me ignore them in hard-MAC drivers by accessing data and not head?

I.e., does this dgram (and a later seqpacket) implementation give us not
just the buffer to pass to hard-MAC or soft-MAC but actually LoRa, too,
so that maclorawan needs to further post-processing of header/checksum?

> +	return 0;
> +}
> +
> +static int
> +dgram_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
> +{
> +	struct dgram_sock *ro = dgram_sk(sk);
> +	struct net_device *ndev;
> +	struct sk_buff *skb;
> +	size_t hlen;
> +	size_t tlen;
> +	int ret;
> +
> +	pr_debug("%s: going to send %zu bytes", __func__, size);

\n

> +	if (msg->msg_flags & MSG_OOB) {
> +		pr_debug("msg->msg_flags = 0x%x\n", msg->msg_flags);
> +		return -EOPNOTSUPP;
> +	}
> +
> +	pr_debug("%s: check msg_name\n", __func__);
> +	if (!ro->connected && !msg->msg_name)
> +		return -EDESTADDRREQ;
> +	else if (ro->connected && msg->msg_name)
> +		return -EISCONN;
> +
> +	pr_debug("%s: check bound\n", __func__);
> +	if (!ro->bound)
> +		ndev = dev_getfirstbyhwtype(sock_net(sk), ARPHRD_LORAWAN);
> +	else
> +		ndev = lrw_get_dev_by_addr(sock_net(sk), ro->src_devaddr);
> +
> +	if (!ndev) {
> +		pr_debug("no dev\n");
> +		ret = -ENXIO;
> +		goto dgram_sendmsg_end;
> +	}
> +
> +	if (size > ndev->mtu) {
> +		netdev_dbg(ndev, "size = %zu, mtu = %u\n", size, ndev->mtu);
> +		ret = -EMSGSIZE;
> +		goto dgram_sendmsg_end;

Leaks at least ndev from lrw_get_dev_by_addr.

> +	}
> +
> +	netdev_dbg(ndev, "%s: create skb\n", __func__);
> +	hlen = LL_RESERVED_SPACE(ndev);
> +	tlen = ndev->needed_tailroom;
> +	skb = sock_alloc_send_skb(sk, hlen + tlen + size,
> +				  msg->msg_flags & MSG_DONTWAIT,
> +				  &ret);
> +
> +	if (!skb)
> +		goto dgram_sendmsg_no_skb;
> +
> +	skb_reserve(skb, hlen);
> +	skb_reset_network_header(skb);
> +
> +	ret = lrw_dev_hard_header(skb, ndev, 0, size);
> +	if (ret < 0)
> +		goto dgram_sendmsg_no_skb;
> +
> +	ret = memcpy_from_msg(skb_put(skb, size), msg, size);
> +	if (ret > 0)
> +		goto dgram_sendmsg_err_skb;
> +
> +	skb->dev = ndev;
> +	skb->protocol = htons(ETH_P_LORAWAN);
> +
> +	netdev_dbg(ndev, "%s: push skb to xmit queue\n", __func__);
> +	ret = dev_queue_xmit(skb);
> +	if (ret > 0)
> +		ret = net_xmit_errno(ret);
> +	netdev_dbg(ndev, "%s: pushed skb to xmit queue with ret=%d\n",
> +		   __func__, ret);
> +	dev_put(ndev);
> +
> +	return ret ?: size;
> +
> +dgram_sendmsg_err_skb:
> +	kfree_skb(skb);
> +dgram_sendmsg_no_skb:
> +	dev_put(ndev);
> +
> +dgram_sendmsg_end:
> +	return ret;
> +}
> +
> +static int
> +dgram_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
> +	      int noblock, int flags, int *addr_len)
> +{
> +	DECLARE_SOCKADDR(struct sockaddr_lorawan *, saddr, msg->msg_name);
> +	struct sk_buff *skb;
> +	size_t copied = 0;
> +	int err;
> +
> +	skb = skb_recv_datagram(sk, flags, noblock, &err);
> +	if (!skb)
> +		goto dgram_recvmsg_end;
> +
> +	copied = skb->len;
> +	if (len < copied) {
> +		msg->msg_flags |= MSG_TRUNC;
> +		copied = len;
> +	}
> +
> +	err = skb_copy_datagram_msg(skb, 0, msg, copied);
> +	if (err)
> +		goto dgram_recvmsg_done;
> +
> +	sock_recv_ts_and_drops(msg, sk, skb);
> +	if (saddr) {
> +		memset(saddr, 0, sizeof(*saddr));
> +		saddr->family = AF_LORAWAN;
> +		saddr->addr_in.devaddr = lrw_get_mac_cb(skb)->devaddr;
> +		*addr_len = sizeof(*saddr);
> +	}
> +
> +	if (flags & MSG_TRUNC)
> +		copied = skb->len;
> +
> +dgram_recvmsg_done:
> +	skb_free_datagram(sk, skb);
> +
> +dgram_recvmsg_end:
> +	if (err)
> +		return err;
> +	return copied;
> +}
> +
> +static int
> +dgram_hash(struct sock *sk)
> +{
> +	pr_debug("%s\n", __func__);
> +	write_lock_bh(&dgram_lock);
> +	sk_add_node(sk, &dgram_head);
> +	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
> +	write_unlock_bh(&dgram_lock);
> +
> +	return 0;
> +}
> +
> +static void
> +dgram_unhash(struct sock *sk)
> +{
> +	pr_debug("%s\n", __func__);
> +	write_lock_bh(&dgram_lock);
> +	if (sk_del_node_init(sk))
> +		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
> +	write_unlock_bh(&dgram_lock);
> +}
> +
> +static int
> +dgram_connect(struct sock *sk, struct sockaddr *uaddr, int len)
> +{
> +	struct dgram_sock *ro = dgram_sk(sk);
> +
> +	/* Nodes of LoRaWAN send data to a gateway only, then data is received
> +	 * and transferred to servers with the gateway's policy.
> +	 * So, the destination address is not used by nodes.
> +	 */
> +	lock_sock(sk);
> +	ro->connected = 1;
> +	release_sock(sk);
> +
> +	return 0;
> +}
> +
> +static int
> +dgram_disconnect(struct sock *sk, int flags)
> +{
> +	struct dgram_sock *ro = dgram_sk(sk);
> +
> +	lock_sock(sk);
> +	ro->connected = 0;
> +	release_sock(sk);
> +
> +	return 0;
> +}
> +
> +static int
> +dgram_ioctl(struct sock *sk, int cmd, unsigned long arg)
> +{
> +	struct net_device *ndev = sk->sk_dst_cache->dev;
> +	struct sk_buff *skb;
> +	int amount;
> +	int err;
> +
> +	netdev_dbg(ndev, "%s: ioctl file (cmd=0x%X)\n", __func__, cmd);
> +	switch (cmd) {
> +	case SIOCOUTQ:
> +		amount = sk_wmem_alloc_get(sk);
> +		err = put_user(amount, (int __user *)arg);
> +		break;
> +	case SIOCINQ:
> +		amount = 0;
> +		spin_lock_bh(&sk->sk_receive_queue.lock);
> +		skb = skb_peek(&sk->sk_receive_queue);
> +		if (skb) {
> +			/* We will only return the amount of this packet
> +			 * since that is all that will be read.
> +			 */
> +			amount = skb->len;
> +		}
> +		spin_unlock_bh(&sk->sk_receive_queue.lock);
> +		err = put_user(amount, (int __user *)arg);
> +		break;
> +	default:
> +		err = -ENOIOCTLCMD;
> +	}
> +
> +	return err;
> +}
> +
> +static int
> +dgram_getsockopt(struct sock *sk, int level, int optname,
> +		 char __user *optval, int __user *optlen)
> +{
> +	int val, len;
> +
> +	if (level != SOL_LORAWAN)
> +		return -EOPNOTSUPP;
> +
> +	if (get_user(len, optlen))
> +		return -EFAULT;
> +
> +	len = min_t(unsigned int, len, sizeof(int));
> +
> +	switch (optname) {
> +	default:
> +		return -ENOPROTOOPT;
> +	}
> +
> +	if (put_user(len, optlen))
> +		return -EFAULT;
> +
> +	if (copy_to_user(optval, &val, len))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +
> +static int
> +dgram_setsockopt(struct sock *sk, int level, int optname,
> +		 char __user *optval, unsigned int optlen)
> +{
> +	int val;
> +	int err;
> +
> +	err = 0;
> +
> +	if (optlen < sizeof(int))
> +		return -EINVAL;
> +
> +	if (get_user(val, (int __user *)optval))
> +		return -EFAULT;
> +
> +	lock_sock(sk);
> +
> +	switch (optname) {
> +	default:
> +		err = -ENOPROTOOPT;
> +		break;
> +	}
> +
> +	release_sock(sk);
> +
> +	return err;
> +}
> +
> +static struct proto lrw_dgram_prot = {
> +	.name		= "LoRaWAN",
> +	.owner		= THIS_MODULE,
> +	.obj_size	= sizeof(struct dgram_sock),
> +	.init		= dgram_init,
> +	.close		= dgram_close,
> +	.bind		= dgram_bind,
> +	.sendmsg	= dgram_sendmsg,
> +	.recvmsg	= dgram_recvmsg,
> +	.hash		= dgram_hash,
> +	.unhash		= dgram_unhash,
> +	.connect	= dgram_connect,
> +	.disconnect	= dgram_disconnect,
> +	.ioctl		= dgram_ioctl,
> +	.getsockopt	= dgram_getsockopt,
> +	.setsockopt	= dgram_setsockopt,
> +};
> +
> +static int
> +lrw_sock_release(struct socket *sock)
> +{
> +	struct sock *sk = sock->sk;
> +
> +	if (sk) {
> +		sock->sk = NULL;
> +		sk->sk_prot->close(sk, 0);
> +	}
> +
> +	return 0;
> +}
> +
> +static int
> +lrw_sock_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
> +{
> +	struct sockaddr_lorawan *addr = (struct sockaddr_lorawan *)uaddr;
> +	struct sock *sk = sock->sk;
> +
> +	pr_debug("%s: bind address %X\n", __func__, addr->addr_in.devaddr);
> +	if (sk->sk_prot->bind)
> +		return sk->sk_prot->bind(sk, uaddr, addr_len);
> +
> +	return sock_no_bind(sock, uaddr, addr_len);
> +}
> +
> +static int
> +lrw_sock_connect(struct socket *sock, struct sockaddr *uaddr,
> +		 int addr_len, int flags)
> +{
> +	struct sock *sk = sock->sk;
> +
> +	if (addr_len < sizeof(uaddr->sa_family))
> +		return -EINVAL;
> +
> +	return sk->sk_prot->connect(sk, uaddr, addr_len);
> +}
> +
> +static int
> +lrw_ndev_ioctl(struct sock *sk, struct ifreq __user *arg, unsigned int cmd)
> +{
> +	struct net_device *ndev;
> +	struct ifreq ifr;
> +	int ret;
> +
> +	pr_debug("%s: cmd %ud\n", __func__, cmd);
> +	ret = -ENOIOCTLCMD;
> +
> +	if (copy_from_user(&ifr, arg, sizeof(struct ifreq)))
> +		return -EFAULT;
> +
> +	ifr.ifr_name[IFNAMSIZ - 1] = 0;
> +
> +	dev_load(sock_net(sk), ifr.ifr_name);
> +	ndev = dev_get_by_name(sock_net(sk), ifr.ifr_name);
> +
> +	netdev_dbg(ndev, "%s: cmd %ud\n", __func__, cmd);
> +	if (!ndev)
> +		return -ENODEV;
> +
> +	if (ndev->type == ARPHRD_LORAWAN && ndev->netdev_ops->ndo_do_ioctl)
> +		ret = ndev->netdev_ops->ndo_do_ioctl(ndev, &ifr, cmd);
> +
> +	if (!ret && copy_to_user(arg, &ifr, sizeof(struct ifreq)))
> +		ret = -EFAULT;
> +	dev_put(ndev);
> +
> +	return ret;
> +}
> +
> +static int
> +lrw_sock_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
> +{
> +	struct sock *sk = sock->sk;
> +
> +	pr_debug("%s: cmd %ud\n", __func__, cmd);
> +	switch (cmd) {
> +	case SIOCGSTAMP:
> +		return sock_get_timestamp(sk, (struct timeval __user *)arg);
> +	case SIOCGSTAMPNS:
> +		return sock_get_timestampns(sk, (struct timespec __user *)arg);
> +	case SIOCOUTQ:
> +	case SIOCINQ:
> +		if (!sk->sk_prot->ioctl)
> +			return -ENOIOCTLCMD;
> +		return sk->sk_prot->ioctl(sk, cmd, arg);
> +	default:
> +		return lrw_ndev_ioctl(sk, (struct ifreq __user *)arg, cmd);
> +	}
> +}
> +
> +static int
> +lrw_sock_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
> +{
> +	struct sock *sk = sock->sk;
> +
> +	pr_debug("%s: going to send %zu bytes\n", __func__, len);
> +	return sk->sk_prot->sendmsg(sk, msg, len);
> +}
> +
> +static const struct proto_ops lrw_dgram_ops = {
> +	.family		= PF_LORAWAN,
> +	.owner		= THIS_MODULE,
> +	.release	= lrw_sock_release,
> +	.bind		= lrw_sock_bind,
> +	.connect	= lrw_sock_connect,
> +	.socketpair	= sock_no_socketpair,
> +	.accept		= sock_no_accept,
> +	.getname	= sock_no_getname,
> +	.poll		= datagram_poll,
> +	.ioctl		= lrw_sock_ioctl,
> +	.listen		= sock_no_listen,
> +	.shutdown	= sock_no_shutdown,
> +	.setsockopt	= sock_common_setsockopt,
> +	.getsockopt	= sock_common_getsockopt,
> +	.sendmsg	= lrw_sock_sendmsg,
> +	.recvmsg	= sock_common_recvmsg,
> +	.mmap		= sock_no_mmap,
> +	.sendpage	= sock_no_sendpage,
> +};
> +
> +static int
> +lorawan_creat(struct net *net, struct socket *sock, int protocol, int kern)

create
Also, why lorawan_ here and lrw_ elsewhere?

> +{
> +	struct sock *sk;
> +	int ret;
> +
> +	if (!net_eq(net, &init_net))
> +		return -EAFNOSUPPORT;
> +
> +	if (sock->type != SOCK_DGRAM)
> +		return -EAFNOSUPPORT;
> +
> +	/* Allocates enough memory for dgram_sock whose first member is sk */
> +	sk = sk_alloc(net, PF_LORAWAN, GFP_KERNEL, &lrw_dgram_prot, kern);
> +	if (!sk)
> +		return -ENOMEM;
> +
> +	sock->ops = &lrw_dgram_ops;
> +	sock_init_data(sock, sk);
> +	sk->sk_family = PF_LORAWAN;
> +	sock_set_flag(sk, SOCK_ZAPPED);
> +
> +	if (sk->sk_prot->hash) {
> +		ret = sk->sk_prot->hash(sk);
> +		if (ret) {
> +			sk_common_release(sk);
> +			goto lorawan_creat_end;
> +		}
> +	}
> +
> +	if (sk->sk_prot->init) {
> +		ret = sk->sk_prot->init(sk);
> +		if (ret)
> +			sk_common_release(sk);
> +	}
> +
> +lorawan_creat_end:

create

> +	return ret;
> +}
> +
> +static const struct net_proto_family lorawan_family_ops = {
> +	.owner		= THIS_MODULE,
> +	.family		= PF_LORAWAN,
> +	.create		= lorawan_creat,
> +};
> +
> +static int
> +lrw_dgram_deliver(struct net_device *ndev, struct sk_buff *skb)
> +{
> +	struct dgram_sock *ro;
> +	struct sock *sk;
> +	bool found;
> +	int ret;
> +
> +	ret = NET_RX_SUCCESS;
> +	found = false;

In times of C99 you could probably fold that into the declarations.

> +
> +	read_lock(&dgram_lock);
> +	sk_for_each(sk, &dgram_head) {
> +		ro = dgram_sk(sk);
> +		if (cpu_to_be32(ro->src_devaddr) == *(__be32 *)ndev->dev_addr) {
> +			found = true;
> +			break;
> +		}
> +	}
> +	read_unlock(&dgram_lock);
> +
> +	if (!found)
> +		goto lrw_dgram_deliver_err;
> +
> +	skb = skb_share_check(skb, GFP_ATOMIC);
> +	if (!skb)
> +		return NET_RX_DROP;
> +
> +	if (sock_queue_rcv_skb(sk, skb) < 0)
> +		goto lrw_dgram_deliver_err;
> +
> +	return ret;
> +
> +lrw_dgram_deliver_err:
> +	kfree_skb(skb);
> +	ret = NET_RX_DROP;
> +	return ret;
> +}
> +
> +static int
> +lorawan_rcv(struct sk_buff *skb, struct net_device *ndev,
> +	    struct packet_type *pt, struct net_device *orig_ndev)
> +{
> +	if (!netif_running(ndev))
> +		goto lorawan_rcv_drop;
> +
> +	if (!net_eq(dev_net(ndev), &init_net))
> +		goto lorawan_rcv_drop;
> +
> +	if (ndev->type != ARPHRD_LORAWAN)
> +		goto lorawan_rcv_drop;
> +
> +	if (skb->pkt_type != PACKET_OTHERHOST)
> +		return lrw_dgram_deliver(ndev, skb);
> +
> +lorawan_rcv_drop:
> +	kfree_skb(skb);
> +	return NET_RX_DROP;
> +}
> +
> +static struct packet_type lorawan_packet_type = {
> +	.type		= htons(ETH_P_LORAWAN),
> +	.func		= lorawan_rcv,
> +};
> +
> +static int __init
> +lrw_sock_init(void)
> +{
> +	int ret;
> +
> +	pr_info("module inserted\n");
> +	ret = proto_register(&lrw_dgram_prot, 1);
> +	if (ret)
> +		goto lrw_sock_init_end;
> +
> +	/* Tell SOCKET that we are alive */

Drop?

> +	ret = sock_register(&lorawan_family_ops);
> +	if (ret)
> +		goto lrw_sock_init_err;
> +
> +	dev_add_pack(&lorawan_packet_type);
> +	ret = 0;
> +	goto lrw_sock_init_end;
> +
> +lrw_sock_init_err:
> +	proto_unregister(&lrw_dgram_prot);
> +
> +lrw_sock_init_end:
> +	return 0;

return ret;?

> +}
> +
> +static void __exit
> +lrw_sock_exit(void)
> +{
> +	dev_remove_pack(&lorawan_packet_type);
> +	sock_unregister(PF_LORAWAN);
> +	proto_unregister(&lrw_dgram_prot);
> +	pr_info("module removed\n");
> +}
> +
> +module_init(lrw_sock_init);
> +module_exit(lrw_sock_exit);
> +
> +MODULE_AUTHOR("Jian-Hong Pan, <starnight@g.ncu.edu.tw>");

Drop the comma?

> +MODULE_DESCRIPTION("LoRaWAN socket kernel module");

Aren't they all kernel modules? :)

> +MODULE_LICENSE("Dual BSD/GPL");
> +MODULE_ALIAS_NETPROTO(PF_LORAWAN);

Regards,
Andreas

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