// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
/*
 * Copyright (c) 2015, Sony Mobile Communications Inc.
 * Copyright (c) 2013, The Linux Foundation. All rights reserved.
 * Copyright (c) 2020, Linaro Ltd.
 */

#include <linux/module.h>
#include <linux/qrtr.h>
#include <linux/workqueue.h>
#include <net/sock.h>

#include "qrtr.h"

#define CREATE_TRACE_POINTS
#include <trace/events/qrtr.h>

static RADIX_TREE(nodes, GFP_KERNEL);

static struct {
	struct socket *sock;
	struct sockaddr_qrtr bcast_sq;
	struct list_head lookups;
	struct workqueue_struct *workqueue;
	struct work_struct work;
	int local_node;
} qrtr_ns;

static const char * const qrtr_ctrl_pkt_strings[] = {
	[QRTR_TYPE_HELLO]	= "hello",
	[QRTR_TYPE_BYE]		= "bye",
	[QRTR_TYPE_NEW_SERVER]	= "new-server",
	[QRTR_TYPE_DEL_SERVER]	= "del-server",
	[QRTR_TYPE_DEL_CLIENT]	= "del-client",
	[QRTR_TYPE_RESUME_TX]	= "resume-tx",
	[QRTR_TYPE_EXIT]	= "exit",
	[QRTR_TYPE_PING]	= "ping",
	[QRTR_TYPE_NEW_LOOKUP]	= "new-lookup",
	[QRTR_TYPE_DEL_LOOKUP]	= "del-lookup",
};

struct qrtr_server_filter {
	unsigned int service;
	unsigned int instance;
	unsigned int ifilter;
};

struct qrtr_lookup {
	unsigned int service;
	unsigned int instance;

	struct sockaddr_qrtr sq;
	struct list_head li;
};

struct qrtr_server {
	unsigned int service;
	unsigned int instance;

	unsigned int node;
	unsigned int port;

	struct list_head qli;
};

struct qrtr_node {
	unsigned int id;
	struct radix_tree_root servers;
};

static struct qrtr_node *node_get(unsigned int node_id)
{
	struct qrtr_node *node;

	node = radix_tree_lookup(&nodes, node_id);
	if (node)
		return node;

	/* If node didn't exist, allocate and insert it to the tree */
	node = kzalloc(sizeof(*node), GFP_KERNEL);
	if (!node)
		return NULL;

	node->id = node_id;

	if (radix_tree_insert(&nodes, node_id, node)) {
		kfree(node);
		return NULL;
	}

	return node;
}

static int server_match(const struct qrtr_server *srv,
			const struct qrtr_server_filter *f)
{
	unsigned int ifilter = f->ifilter;

	if (f->service != 0 && srv->service != f->service)
		return 0;
	if (!ifilter && f->instance)
		ifilter = ~0;

	return (srv->instance & ifilter) == f->instance;
}

static int service_announce_new(struct sockaddr_qrtr *dest,
				struct qrtr_server *srv)
{
	struct qrtr_ctrl_pkt pkt;
	struct msghdr msg = { };
	struct kvec iv;

	trace_qrtr_ns_service_announce_new(srv->service, srv->instance,
					   srv->node, srv->port);

	iv.iov_base = &pkt;
	iv.iov_len = sizeof(pkt);

	memset(&pkt, 0, sizeof(pkt));
	pkt.cmd = cpu_to_le32(QRTR_TYPE_NEW_SERVER);
	pkt.server.service = cpu_to_le32(srv->service);
	pkt.server.instance = cpu_to_le32(srv->instance);
	pkt.server.node = cpu_to_le32(srv->node);
	pkt.server.port = cpu_to_le32(srv->port);

	msg.msg_name = (struct sockaddr *)dest;
	msg.msg_namelen = sizeof(*dest);

	return kernel_sendmsg(qrtr_ns.sock, &msg, &iv, 1, sizeof(pkt));
}

static int service_announce_del(struct sockaddr_qrtr *dest,
				struct qrtr_server *srv)
{
	struct qrtr_ctrl_pkt pkt;
	struct msghdr msg = { };
	struct kvec iv;
	int ret;

	trace_qrtr_ns_service_announce_del(srv->service, srv->instance,
					   srv->node, srv->port);

	iv.iov_base = &pkt;
	iv.iov_len = sizeof(pkt);

	memset(&pkt, 0, sizeof(pkt));
	pkt.cmd = cpu_to_le32(QRTR_TYPE_DEL_SERVER);
	pkt.server.service = cpu_to_le32(srv->service);
	pkt.server.instance = cpu_to_le32(srv->instance);
	pkt.server.node = cpu_to_le32(srv->node);
	pkt.server.port = cpu_to_le32(srv->port);

	msg.msg_name = (struct sockaddr *)dest;
	msg.msg_namelen = sizeof(*dest);

	ret = kernel_sendmsg(qrtr_ns.sock, &msg, &iv, 1, sizeof(pkt));
	if (ret < 0)
		pr_err("failed to announce del service\n");

	return ret;
}

static void lookup_notify(struct sockaddr_qrtr *to, struct qrtr_server *srv,
			  bool new)
{
	struct qrtr_ctrl_pkt pkt;
	struct msghdr msg = { };
	struct kvec iv;
	int ret;

	iv.iov_base = &pkt;
	iv.iov_len = sizeof(pkt);

	memset(&pkt, 0, sizeof(pkt));
	pkt.cmd = new ? cpu_to_le32(QRTR_TYPE_NEW_SERVER) :
			cpu_to_le32(QRTR_TYPE_DEL_SERVER);
	if (srv) {
		pkt.server.service = cpu_to_le32(srv->service);
		pkt.server.instance = cpu_to_le32(srv->instance);
		pkt.server.node = cpu_to_le32(srv->node);
		pkt.server.port = cpu_to_le32(srv->port);
	}

	msg.msg_name = (struct sockaddr *)to;
	msg.msg_namelen = sizeof(*to);

	ret = kernel_sendmsg(qrtr_ns.sock, &msg, &iv, 1, sizeof(pkt));
	if (ret < 0)
		pr_err("failed to send lookup notification\n");
}

static int announce_servers(struct sockaddr_qrtr *sq)
{
	struct radix_tree_iter iter;
	struct qrtr_server *srv;
	struct qrtr_node *node;
	void __rcu **slot;
	int ret;

	node = node_get(qrtr_ns.local_node);
	if (!node)
		return 0;

	rcu_read_lock();
	/* Announce the list of servers registered in this node */
	radix_tree_for_each_slot(slot, &node->servers, &iter, 0) {
		srv = radix_tree_deref_slot(slot);
		if (!srv)
			continue;
		if (radix_tree_deref_retry(srv)) {
			slot = radix_tree_iter_retry(&iter);
			continue;
		}
		slot = radix_tree_iter_resume(slot, &iter);
		rcu_read_unlock();

		ret = service_announce_new(sq, srv);
		if (ret < 0) {
			pr_err("failed to announce new service\n");
			return ret;
		}

		rcu_read_lock();
	}

	rcu_read_unlock();

	return 0;
}

static struct qrtr_server *server_add(unsigned int service,
				      unsigned int instance,
				      unsigned int node_id,
				      unsigned int port)
{
	struct qrtr_server *srv;
	struct qrtr_server *old;
	struct qrtr_node *node;

	if (!service || !port)
		return NULL;

	srv = kzalloc(sizeof(*srv), GFP_KERNEL);
	if (!srv)
		return NULL;

	srv->service = service;
	srv->instance = instance;
	srv->node = node_id;
	srv->port = port;

	node = node_get(node_id);
	if (!node)
		goto err;

	/* Delete the old server on the same port */
	old = radix_tree_lookup(&node->servers, port);
	if (old) {
		radix_tree_delete(&node->servers, port);
		kfree(old);
	}

	radix_tree_insert(&node->servers, port, srv);

	trace_qrtr_ns_server_add(srv->service, srv->instance,
				 srv->node, srv->port);

	return srv;

err:
	kfree(srv);
	return NULL;
}

static int server_del(struct qrtr_node *node, unsigned int port, bool bcast)
{
	struct qrtr_lookup *lookup;
	struct qrtr_server *srv;
	struct list_head *li;

	srv = radix_tree_lookup(&node->servers, port);
	if (!srv)
		return -ENOENT;

	radix_tree_delete(&node->servers, port);

	/* Broadcast the removal of local servers */
	if (srv->node == qrtr_ns.local_node && bcast)
		service_announce_del(&qrtr_ns.bcast_sq, srv);

	/* Announce the service's disappearance to observers */
	list_for_each(li, &qrtr_ns.lookups) {
		lookup = container_of(li, struct qrtr_lookup, li);
		if (lookup->service && lookup->service != srv->service)
			continue;
		if (lookup->instance && lookup->instance != srv->instance)
			continue;

		lookup_notify(&lookup->sq, srv, false);
	}

	kfree(srv);

	return 0;
}

static int say_hello(struct sockaddr_qrtr *dest)
{
	struct qrtr_ctrl_pkt pkt;
	struct msghdr msg = { };
	struct kvec iv;
	int ret;

	iv.iov_base = &pkt;
	iv.iov_len = sizeof(pkt);

	memset(&pkt, 0, sizeof(pkt));
	pkt.cmd = cpu_to_le32(QRTR_TYPE_HELLO);

	msg.msg_name = (struct sockaddr *)dest;
	msg.msg_namelen = sizeof(*dest);

	ret = kernel_sendmsg(qrtr_ns.sock, &msg, &iv, 1, sizeof(pkt));
	if (ret < 0)
		pr_err("failed to send hello msg\n");

	return ret;
}

/* Announce the list of servers registered on the local node */
static int ctrl_cmd_hello(struct sockaddr_qrtr *sq)
{
	int ret;

	ret = say_hello(sq);
	if (ret < 0)
		return ret;

	return announce_servers(sq);
}

static int ctrl_cmd_bye(struct sockaddr_qrtr *from)
{
	struct qrtr_node *local_node;
	struct radix_tree_iter iter;
	struct qrtr_ctrl_pkt pkt;
	struct qrtr_server *srv;
	struct sockaddr_qrtr sq;
	struct msghdr msg = { };
	struct qrtr_node *node;
	void __rcu **slot;
	struct kvec iv;
	int ret;

	iv.iov_base = &pkt;
	iv.iov_len = sizeof(pkt);

	node = node_get(from->sq_node);
	if (!node)
		return 0;

	rcu_read_lock();
	/* Advertise removal of this client to all servers of remote node */
	radix_tree_for_each_slot(slot, &node->servers, &iter, 0) {
		srv = radix_tree_deref_slot(slot);
		if (!srv)
			continue;
		if (radix_tree_deref_retry(srv)) {
			slot = radix_tree_iter_retry(&iter);
			continue;
		}
		slot = radix_tree_iter_resume(slot, &iter);
		rcu_read_unlock();
		server_del(node, srv->port, true);
		rcu_read_lock();
	}
	rcu_read_unlock();

	/* Advertise the removal of this client to all local servers */
	local_node = node_get(qrtr_ns.local_node);
	if (!local_node)
		return 0;

	memset(&pkt, 0, sizeof(pkt));
	pkt.cmd = cpu_to_le32(QRTR_TYPE_BYE);
	pkt.client.node = cpu_to_le32(from->sq_node);

	rcu_read_lock();
	radix_tree_for_each_slot(slot, &local_node->servers, &iter, 0) {
		srv = radix_tree_deref_slot(slot);
		if (!srv)
			continue;
		if (radix_tree_deref_retry(srv)) {
			slot = radix_tree_iter_retry(&iter);
			continue;
		}
		slot = radix_tree_iter_resume(slot, &iter);
		rcu_read_unlock();

		sq.sq_family = AF_QIPCRTR;
		sq.sq_node = srv->node;
		sq.sq_port = srv->port;

		msg.msg_name = (struct sockaddr *)&sq;
		msg.msg_namelen = sizeof(sq);

		ret = kernel_sendmsg(qrtr_ns.sock, &msg, &iv, 1, sizeof(pkt));
		if (ret < 0) {
			pr_err("failed to send bye cmd\n");
			return ret;
		}
		rcu_read_lock();
	}

	rcu_read_unlock();

	return 0;
}

static int ctrl_cmd_del_client(struct sockaddr_qrtr *from,
			       unsigned int node_id, unsigned int port)
{
	struct qrtr_node *local_node;
	struct radix_tree_iter iter;
	struct qrtr_lookup *lookup;
	struct qrtr_ctrl_pkt pkt;
	struct msghdr msg = { };
	struct qrtr_server *srv;
	struct sockaddr_qrtr sq;
	struct qrtr_node *node;
	struct list_head *tmp;
	struct list_head *li;
	void __rcu **slot;
	struct kvec iv;
	int ret;

	iv.iov_base = &pkt;
	iv.iov_len = sizeof(pkt);

	/* Don't accept spoofed messages */
	if (from->sq_node != node_id)
		return -EINVAL;

	/* Local DEL_CLIENT messages comes from the port being closed */
	if (from->sq_node == qrtr_ns.local_node && from->sq_port != port)
		return -EINVAL;

	/* Remove any lookups by this client */
	list_for_each_safe(li, tmp, &qrtr_ns.lookups) {
		lookup = container_of(li, struct qrtr_lookup, li);
		if (lookup->sq.sq_node != node_id)
			continue;
		if (lookup->sq.sq_port != port)
			continue;

		list_del(&lookup->li);
		kfree(lookup);
	}

	/* Remove the server belonging to this port but don't broadcast
	 * DEL_SERVER. Neighbours would've already removed the server belonging
	 * to this port due to the DEL_CLIENT broadcast from qrtr_port_remove().
	 */
	node = node_get(node_id);
	if (node)
		server_del(node, port, false);

	/* Advertise the removal of this client to all local servers */
	local_node = node_get(qrtr_ns.local_node);
	if (!local_node)
		return 0;

	memset(&pkt, 0, sizeof(pkt));
	pkt.cmd = cpu_to_le32(QRTR_TYPE_DEL_CLIENT);
	pkt.client.node = cpu_to_le32(node_id);
	pkt.client.port = cpu_to_le32(port);

	rcu_read_lock();
	radix_tree_for_each_slot(slot, &local_node->servers, &iter, 0) {
		srv = radix_tree_deref_slot(slot);
		if (!srv)
			continue;
		if (radix_tree_deref_retry(srv)) {
			slot = radix_tree_iter_retry(&iter);
			continue;
		}
		slot = radix_tree_iter_resume(slot, &iter);
		rcu_read_unlock();

		sq.sq_family = AF_QIPCRTR;
		sq.sq_node = srv->node;
		sq.sq_port = srv->port;

		msg.msg_name = (struct sockaddr *)&sq;
		msg.msg_namelen = sizeof(sq);

		ret = kernel_sendmsg(qrtr_ns.sock, &msg, &iv, 1, sizeof(pkt));
		if (ret < 0) {
			pr_err("failed to send del client cmd\n");
			return ret;
		}
		rcu_read_lock();
	}

	rcu_read_unlock();

	return 0;
}

static int ctrl_cmd_new_server(struct sockaddr_qrtr *from,
			       unsigned int service, unsigned int instance,
			       unsigned int node_id, unsigned int port)
{
	struct qrtr_lookup *lookup;
	struct qrtr_server *srv;
	struct list_head *li;
	int ret = 0;

	/* Ignore specified node and port for local servers */
	if (from->sq_node == qrtr_ns.local_node) {
		node_id = from->sq_node;
		port = from->sq_port;
	}

	/* Don't accept spoofed messages */
	if (from->sq_node != node_id)
		return -EINVAL;

	srv = server_add(service, instance, node_id, port);
	if (!srv)
		return -EINVAL;

	if (srv->node == qrtr_ns.local_node) {
		ret = service_announce_new(&qrtr_ns.bcast_sq, srv);
		if (ret < 0) {
			pr_err("failed to announce new service\n");
			return ret;
		}
	}

	/* Notify any potential lookups about the new server */
	list_for_each(li, &qrtr_ns.lookups) {
		lookup = container_of(li, struct qrtr_lookup, li);
		if (lookup->service && lookup->service != service)
			continue;
		if (lookup->instance && lookup->instance != instance)
			continue;

		lookup_notify(&lookup->sq, srv, true);
	}

	return ret;
}

static int ctrl_cmd_del_server(struct sockaddr_qrtr *from,
			       unsigned int service, unsigned int instance,
			       unsigned int node_id, unsigned int port)
{
	struct qrtr_node *node;

	/* Ignore specified node and port for local servers*/
	if (from->sq_node == qrtr_ns.local_node) {
		node_id = from->sq_node;
		port = from->sq_port;
	}

	/* Don't accept spoofed messages */
	if (from->sq_node != node_id)
		return -EINVAL;

	/* Local servers may only unregister themselves */
	if (from->sq_node == qrtr_ns.local_node && from->sq_port != port)
		return -EINVAL;

	node = node_get(node_id);
	if (!node)
		return -ENOENT;

	server_del(node, port, true);

	return 0;
}

static int ctrl_cmd_new_lookup(struct sockaddr_qrtr *from,
			       unsigned int service, unsigned int instance)
{
	struct radix_tree_iter node_iter;
	struct qrtr_server_filter filter;
	struct radix_tree_iter srv_iter;
	struct qrtr_lookup *lookup;
	struct qrtr_node *node;
	void __rcu **node_slot;
	void __rcu **srv_slot;

	/* Accept only local observers */
	if (from->sq_node != qrtr_ns.local_node)
		return -EINVAL;

	lookup = kzalloc(sizeof(*lookup), GFP_KERNEL);
	if (!lookup)
		return -ENOMEM;

	lookup->sq = *from;
	lookup->service = service;
	lookup->instance = instance;
	list_add_tail(&lookup->li, &qrtr_ns.lookups);

	memset(&filter, 0, sizeof(filter));
	filter.service = service;
	filter.instance = instance;

	rcu_read_lock();
	radix_tree_for_each_slot(node_slot, &nodes, &node_iter, 0) {
		node = radix_tree_deref_slot(node_slot);
		if (!node)
			continue;
		if (radix_tree_deref_retry(node)) {
			node_slot = radix_tree_iter_retry(&node_iter);
			continue;
		}
		node_slot = radix_tree_iter_resume(node_slot, &node_iter);

		radix_tree_for_each_slot(srv_slot, &node->servers,
					 &srv_iter, 0) {
			struct qrtr_server *srv;

			srv = radix_tree_deref_slot(srv_slot);
			if (!srv)
				continue;
			if (radix_tree_deref_retry(srv)) {
				srv_slot = radix_tree_iter_retry(&srv_iter);
				continue;
			}

			if (!server_match(srv, &filter))
				continue;

			srv_slot = radix_tree_iter_resume(srv_slot, &srv_iter);

			rcu_read_unlock();
			lookup_notify(from, srv, true);
			rcu_read_lock();
		}
	}
	rcu_read_unlock();

	/* Empty notification, to indicate end of listing */
	lookup_notify(from, NULL, true);

	return 0;
}

static void ctrl_cmd_del_lookup(struct sockaddr_qrtr *from,
				unsigned int service, unsigned int instance)
{
	struct qrtr_lookup *lookup;
	struct list_head *tmp;
	struct list_head *li;

	list_for_each_safe(li, tmp, &qrtr_ns.lookups) {
		lookup = container_of(li, struct qrtr_lookup, li);
		if (lookup->sq.sq_node != from->sq_node)
			continue;
		if (lookup->sq.sq_port != from->sq_port)
			continue;
		if (lookup->service != service)
			continue;
		if (lookup->instance && lookup->instance != instance)
			continue;

		list_del(&lookup->li);
		kfree(lookup);
	}
}

static void qrtr_ns_worker(struct work_struct *work)
{
	const struct qrtr_ctrl_pkt *pkt;
	size_t recv_buf_size = 4096;
	struct sockaddr_qrtr sq;
	struct msghdr msg = { };
	unsigned int cmd;
	ssize_t msglen;
	void *recv_buf;
	struct kvec iv;
	int ret;

	msg.msg_name = (struct sockaddr *)&sq;
	msg.msg_namelen = sizeof(sq);

	recv_buf = kzalloc(recv_buf_size, GFP_KERNEL);
	if (!recv_buf)
		return;

	for (;;) {
		iv.iov_base = recv_buf;
		iv.iov_len = recv_buf_size;

		msglen = kernel_recvmsg(qrtr_ns.sock, &msg, &iv, 1,
					iv.iov_len, MSG_DONTWAIT);

		if (msglen == -EAGAIN)
			break;

		if (msglen < 0) {
			pr_err("error receiving packet: %zd\n", msglen);
			break;
		}

		pkt = recv_buf;
		cmd = le32_to_cpu(pkt->cmd);
		if (cmd < ARRAY_SIZE(qrtr_ctrl_pkt_strings) &&
		    qrtr_ctrl_pkt_strings[cmd])
			trace_qrtr_ns_message(qrtr_ctrl_pkt_strings[cmd],
					      sq.sq_node, sq.sq_port);

		ret = 0;
		switch (cmd) {
		case QRTR_TYPE_HELLO:
			ret = ctrl_cmd_hello(&sq);
			break;
		case QRTR_TYPE_BYE:
			ret = ctrl_cmd_bye(&sq);
			break;
		case QRTR_TYPE_DEL_CLIENT:
			ret = ctrl_cmd_del_client(&sq,
					le32_to_cpu(pkt->client.node),
					le32_to_cpu(pkt->client.port));
			break;
		case QRTR_TYPE_NEW_SERVER:
			ret = ctrl_cmd_new_server(&sq,
					le32_to_cpu(pkt->server.service),
					le32_to_cpu(pkt->server.instance),
					le32_to_cpu(pkt->server.node),
					le32_to_cpu(pkt->server.port));
			break;
		case QRTR_TYPE_DEL_SERVER:
			ret = ctrl_cmd_del_server(&sq,
					 le32_to_cpu(pkt->server.service),
					 le32_to_cpu(pkt->server.instance),
					 le32_to_cpu(pkt->server.node),
					 le32_to_cpu(pkt->server.port));
			break;
		case QRTR_TYPE_EXIT:
		case QRTR_TYPE_PING:
		case QRTR_TYPE_RESUME_TX:
			break;
		case QRTR_TYPE_NEW_LOOKUP:
			ret = ctrl_cmd_new_lookup(&sq,
					 le32_to_cpu(pkt->server.service),
					 le32_to_cpu(pkt->server.instance));
			break;
		case QRTR_TYPE_DEL_LOOKUP:
			ctrl_cmd_del_lookup(&sq,
				    le32_to_cpu(pkt->server.service),
				    le32_to_cpu(pkt->server.instance));
			break;
		}

		if (ret < 0)
			pr_err("failed while handling packet from %d:%d",
			       sq.sq_node, sq.sq_port);
	}

	kfree(recv_buf);
}

static void qrtr_ns_data_ready(struct sock *sk)
{
	queue_work(qrtr_ns.workqueue, &qrtr_ns.work);
}

int qrtr_ns_init(void)
{
	struct sockaddr_qrtr sq;
	int ret;

	INIT_LIST_HEAD(&qrtr_ns.lookups);
	INIT_WORK(&qrtr_ns.work, qrtr_ns_worker);

	ret = sock_create_kern(&init_net, AF_QIPCRTR, SOCK_DGRAM,
			       PF_QIPCRTR, &qrtr_ns.sock);
	if (ret < 0)
		return ret;

	ret = kernel_getsockname(qrtr_ns.sock, (struct sockaddr *)&sq);
	if (ret < 0) {
		pr_err("failed to get socket name\n");
		goto err_sock;
	}

	qrtr_ns.workqueue = alloc_workqueue("qrtr_ns_handler", WQ_UNBOUND, 1);
	if (!qrtr_ns.workqueue) {
		ret = -ENOMEM;
		goto err_sock;
	}

	qrtr_ns.sock->sk->sk_data_ready = qrtr_ns_data_ready;

	sq.sq_port = QRTR_PORT_CTRL;
	qrtr_ns.local_node = sq.sq_node;

	ret = kernel_bind(qrtr_ns.sock, (struct sockaddr *)&sq, sizeof(sq));
	if (ret < 0) {
		pr_err("failed to bind to socket\n");
		goto err_wq;
	}

	qrtr_ns.bcast_sq.sq_family = AF_QIPCRTR;
	qrtr_ns.bcast_sq.sq_node = QRTR_NODE_BCAST;
	qrtr_ns.bcast_sq.sq_port = QRTR_PORT_CTRL;

	ret = say_hello(&qrtr_ns.bcast_sq);
	if (ret < 0)
		goto err_wq;

	/* As the qrtr ns socket owner and creator is the same module, we have
	 * to decrease the qrtr module reference count to guarantee that it
	 * remains zero after the ns socket is created, otherwise, executing
	 * "rmmod" command is unable to make the qrtr module deleted after the
	 *  qrtr module is inserted successfully.
	 *
	 * However, the reference count is increased twice in
	 * sock_create_kern(): one is to increase the reference count of owner
	 * of qrtr socket's proto_ops struct; another is to increment the
	 * reference count of owner of qrtr proto struct. Therefore, we must
	 * decrement the module reference count twice to ensure that it keeps
	 * zero after server's listening socket is created. Of course, we
	 * must bump the module reference count twice as well before the socket
	 * is closed.
	 */
	module_put(qrtr_ns.sock->ops->owner);
	module_put(qrtr_ns.sock->sk->sk_prot_creator->owner);

	return 0;

err_wq:
	destroy_workqueue(qrtr_ns.workqueue);
err_sock:
	sock_release(qrtr_ns.sock);
	return ret;
}
EXPORT_SYMBOL_GPL(qrtr_ns_init);

void qrtr_ns_remove(void)
{
	cancel_work_sync(&qrtr_ns.work);
	destroy_workqueue(qrtr_ns.workqueue);

	/* sock_release() expects the two references that were put during
	 * qrtr_ns_init(). This function is only called during module remove,
	 * so try_stop_module() has already set the refcnt to 0. Use
	 * __module_get() instead of try_module_get() to successfully take two
	 * references.
	 */
	__module_get(qrtr_ns.sock->ops->owner);
	__module_get(qrtr_ns.sock->sk->sk_prot_creator->owner);
	sock_release(qrtr_ns.sock);
}
EXPORT_SYMBOL_GPL(qrtr_ns_remove);

MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>");
MODULE_DESCRIPTION("Qualcomm IPC Router Nameservice");
MODULE_LICENSE("Dual BSD/GPL");
