// SPDX-License-Identifier: GPL-2.0-only
/*
 *
 * Author	Karsten Keil <kkeil@novell.com>
 *
 * Copyright 2008  by Karsten Keil <kkeil@novell.com>
 */

#include <linux/slab.h>
#include <linux/mISDNif.h>
#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/sched/cputime.h>
#include <linux/signal.h>

#include "core.h"

static u_int	*debug;

static inline void
_queue_message(struct mISDNstack *st, struct sk_buff *skb)
{
	struct mISDNhead	*hh = mISDN_HEAD_P(skb);

	if (*debug & DEBUG_QUEUE_FUNC)
		printk(KERN_DEBUG "%s prim(%x) id(%x) %p\n",
		       __func__, hh->prim, hh->id, skb);
	skb_queue_tail(&st->msgq, skb);
	if (likely(!test_bit(mISDN_STACK_STOPPED, &st->status))) {
		test_and_set_bit(mISDN_STACK_WORK, &st->status);
		wake_up_interruptible(&st->workq);
	}
}

static int
mISDN_queue_message(struct mISDNchannel *ch, struct sk_buff *skb)
{
	_queue_message(ch->st, skb);
	return 0;
}

static struct mISDNchannel *
get_channel4id(struct mISDNstack *st, u_int id)
{
	struct mISDNchannel	*ch;

	mutex_lock(&st->lmutex);
	list_for_each_entry(ch, &st->layer2, list) {
		if (id == ch->nr)
			goto unlock;
	}
	ch = NULL;
unlock:
	mutex_unlock(&st->lmutex);
	return ch;
}

static void
send_socklist(struct mISDN_sock_list *sl, struct sk_buff *skb)
{
	struct sock		*sk;
	struct sk_buff		*cskb = NULL;

	read_lock(&sl->lock);
	sk_for_each(sk, &sl->head) {
		if (sk->sk_state != MISDN_BOUND)
			continue;
		if (!cskb)
			cskb = skb_copy(skb, GFP_ATOMIC);
		if (!cskb) {
			printk(KERN_WARNING "%s no skb\n", __func__);
			break;
		}
		if (!sock_queue_rcv_skb(sk, cskb))
			cskb = NULL;
	}
	read_unlock(&sl->lock);
	if (cskb)
		dev_kfree_skb(cskb);
}

static void
send_layer2(struct mISDNstack *st, struct sk_buff *skb)
{
	struct sk_buff		*cskb;
	struct mISDNhead	*hh = mISDN_HEAD_P(skb);
	struct mISDNchannel	*ch;
	int			ret;

	if (!st)
		return;
	mutex_lock(&st->lmutex);
	if ((hh->id & MISDN_ID_ADDR_MASK) == MISDN_ID_ANY) { /* L2 for all */
		list_for_each_entry(ch, &st->layer2, list) {
			if (list_is_last(&ch->list, &st->layer2)) {
				cskb = skb;
				skb = NULL;
			} else {
				cskb = skb_copy(skb, GFP_KERNEL);
			}
			if (cskb) {
				ret = ch->send(ch, cskb);
				if (ret) {
					if (*debug & DEBUG_SEND_ERR)
						printk(KERN_DEBUG
						       "%s ch%d prim(%x) addr(%x)"
						       " err %d\n",
						       __func__, ch->nr,
						       hh->prim, ch->addr, ret);
					dev_kfree_skb(cskb);
				}
			} else {
				printk(KERN_WARNING "%s ch%d addr %x no mem\n",
				       __func__, ch->nr, ch->addr);
				goto out;
			}
		}
	} else {
		list_for_each_entry(ch, &st->layer2, list) {
			if ((hh->id & MISDN_ID_ADDR_MASK) == ch->addr) {
				ret = ch->send(ch, skb);
				if (!ret)
					skb = NULL;
				goto out;
			}
		}
		ret = st->dev->teimgr->ctrl(st->dev->teimgr, CHECK_DATA, skb);
		if (!ret)
			skb = NULL;
		else if (*debug & DEBUG_SEND_ERR)
			printk(KERN_DEBUG
			       "%s mgr prim(%x) err %d\n",
			       __func__, hh->prim, ret);
	}
out:
	mutex_unlock(&st->lmutex);
	if (skb)
		dev_kfree_skb(skb);
}

static inline int
send_msg_to_layer(struct mISDNstack *st, struct sk_buff *skb)
{
	struct mISDNhead	*hh = mISDN_HEAD_P(skb);
	struct mISDNchannel	*ch;
	int	lm;

	lm = hh->prim & MISDN_LAYERMASK;
	if (*debug & DEBUG_QUEUE_FUNC)
		printk(KERN_DEBUG "%s prim(%x) id(%x) %p\n",
		       __func__, hh->prim, hh->id, skb);
	if (lm == 0x1) {
		if (!hlist_empty(&st->l1sock.head)) {
			__net_timestamp(skb);
			send_socklist(&st->l1sock, skb);
		}
		return st->layer1->send(st->layer1, skb);
	} else if (lm == 0x2) {
		if (!hlist_empty(&st->l1sock.head))
			send_socklist(&st->l1sock, skb);
		send_layer2(st, skb);
		return 0;
	} else if (lm == 0x4) {
		ch = get_channel4id(st, hh->id);
		if (ch)
			return ch->send(ch, skb);
		else
			printk(KERN_WARNING
			       "%s: dev(%s) prim(%x) id(%x) no channel\n",
			       __func__, dev_name(&st->dev->dev), hh->prim,
			       hh->id);
	} else if (lm == 0x8) {
		WARN_ON(lm == 0x8);
		ch = get_channel4id(st, hh->id);
		if (ch)
			return ch->send(ch, skb);
		else
			printk(KERN_WARNING
			       "%s: dev(%s) prim(%x) id(%x) no channel\n",
			       __func__, dev_name(&st->dev->dev), hh->prim,
			       hh->id);
	} else {
		/* broadcast not handled yet */
		printk(KERN_WARNING "%s: dev(%s) prim %x not delivered\n",
		       __func__, dev_name(&st->dev->dev), hh->prim);
	}
	return -ESRCH;
}

static void
do_clear_stack(struct mISDNstack *st)
{
}

static int
mISDNStackd(void *data)
{
	struct mISDNstack *st = data;
#ifdef MISDN_MSG_STATS
	u64 utime, stime;
#endif
	int err = 0;

	sigfillset(&current->blocked);
	if (*debug & DEBUG_MSG_THREAD)
		printk(KERN_DEBUG "mISDNStackd %s started\n",
		       dev_name(&st->dev->dev));

	if (st->notify != NULL) {
		complete(st->notify);
		st->notify = NULL;
	}

	for (;;) {
		struct sk_buff	*skb;

		if (unlikely(test_bit(mISDN_STACK_STOPPED, &st->status))) {
			test_and_clear_bit(mISDN_STACK_WORK, &st->status);
			test_and_clear_bit(mISDN_STACK_RUNNING, &st->status);
		} else
			test_and_set_bit(mISDN_STACK_RUNNING, &st->status);
		while (test_bit(mISDN_STACK_WORK, &st->status)) {
			skb = skb_dequeue(&st->msgq);
			if (!skb) {
				test_and_clear_bit(mISDN_STACK_WORK,
						   &st->status);
				/* test if a race happens */
				skb = skb_dequeue(&st->msgq);
				if (!skb)
					continue;
				test_and_set_bit(mISDN_STACK_WORK,
						 &st->status);
			}
#ifdef MISDN_MSG_STATS
			st->msg_cnt++;
#endif
			err = send_msg_to_layer(st, skb);
			if (unlikely(err)) {
				if (*debug & DEBUG_SEND_ERR)
					printk(KERN_DEBUG
					       "%s: %s prim(%x) id(%x) "
					       "send call(%d)\n",
					       __func__, dev_name(&st->dev->dev),
					       mISDN_HEAD_PRIM(skb),
					       mISDN_HEAD_ID(skb), err);
				dev_kfree_skb(skb);
				continue;
			}
			if (unlikely(test_bit(mISDN_STACK_STOPPED,
					      &st->status))) {
				test_and_clear_bit(mISDN_STACK_WORK,
						   &st->status);
				test_and_clear_bit(mISDN_STACK_RUNNING,
						   &st->status);
				break;
			}
		}
		if (test_bit(mISDN_STACK_CLEARING, &st->status)) {
			test_and_set_bit(mISDN_STACK_STOPPED, &st->status);
			test_and_clear_bit(mISDN_STACK_RUNNING, &st->status);
			do_clear_stack(st);
			test_and_clear_bit(mISDN_STACK_CLEARING, &st->status);
			test_and_set_bit(mISDN_STACK_RESTART, &st->status);
		}
		if (test_and_clear_bit(mISDN_STACK_RESTART, &st->status)) {
			test_and_clear_bit(mISDN_STACK_STOPPED, &st->status);
			test_and_set_bit(mISDN_STACK_RUNNING, &st->status);
			if (!skb_queue_empty(&st->msgq))
				test_and_set_bit(mISDN_STACK_WORK,
						 &st->status);
		}
		if (test_bit(mISDN_STACK_ABORT, &st->status))
			break;
		if (st->notify != NULL) {
			complete(st->notify);
			st->notify = NULL;
		}
#ifdef MISDN_MSG_STATS
		st->sleep_cnt++;
#endif
		test_and_clear_bit(mISDN_STACK_ACTIVE, &st->status);
		wait_event_interruptible(st->workq, (st->status &
						     mISDN_STACK_ACTION_MASK));
		if (*debug & DEBUG_MSG_THREAD)
			printk(KERN_DEBUG "%s: %s wake status %08lx\n",
			       __func__, dev_name(&st->dev->dev), st->status);
		test_and_set_bit(mISDN_STACK_ACTIVE, &st->status);

		test_and_clear_bit(mISDN_STACK_WAKEUP, &st->status);

		if (test_bit(mISDN_STACK_STOPPED, &st->status)) {
			test_and_clear_bit(mISDN_STACK_RUNNING, &st->status);
#ifdef MISDN_MSG_STATS
			st->stopped_cnt++;
#endif
		}
	}
#ifdef MISDN_MSG_STATS
	printk(KERN_DEBUG "mISDNStackd daemon for %s proceed %d "
	       "msg %d sleep %d stopped\n",
	       dev_name(&st->dev->dev), st->msg_cnt, st->sleep_cnt,
	       st->stopped_cnt);
	task_cputime(st->thread, &utime, &stime);
	printk(KERN_DEBUG
	       "mISDNStackd daemon for %s utime(%llu) stime(%llu)\n",
	       dev_name(&st->dev->dev), utime, stime);
	printk(KERN_DEBUG
	       "mISDNStackd daemon for %s nvcsw(%ld) nivcsw(%ld)\n",
	       dev_name(&st->dev->dev), st->thread->nvcsw, st->thread->nivcsw);
	printk(KERN_DEBUG "mISDNStackd daemon for %s killed now\n",
	       dev_name(&st->dev->dev));
#endif
	test_and_set_bit(mISDN_STACK_KILLED, &st->status);
	test_and_clear_bit(mISDN_STACK_RUNNING, &st->status);
	test_and_clear_bit(mISDN_STACK_ACTIVE, &st->status);
	test_and_clear_bit(mISDN_STACK_ABORT, &st->status);
	skb_queue_purge(&st->msgq);
	st->thread = NULL;
	if (st->notify != NULL) {
		complete(st->notify);
		st->notify = NULL;
	}
	return 0;
}

static int
l1_receive(struct mISDNchannel *ch, struct sk_buff *skb)
{
	if (!ch->st)
		return -ENODEV;
	__net_timestamp(skb);
	_queue_message(ch->st, skb);
	return 0;
}

void
set_channel_address(struct mISDNchannel *ch, u_int sapi, u_int tei)
{
	ch->addr = sapi | (tei << 8);
}

void
__add_layer2(struct mISDNchannel *ch, struct mISDNstack *st)
{
	list_add_tail(&ch->list, &st->layer2);
}

void
add_layer2(struct mISDNchannel *ch, struct mISDNstack *st)
{
	mutex_lock(&st->lmutex);
	__add_layer2(ch, st);
	mutex_unlock(&st->lmutex);
}

static int
st_own_ctrl(struct mISDNchannel *ch, u_int cmd, void *arg)
{
	if (!ch->st || !ch->st->layer1)
		return -EINVAL;
	return ch->st->layer1->ctrl(ch->st->layer1, cmd, arg);
}

int
create_stack(struct mISDNdevice *dev)
{
	struct mISDNstack	*newst;
	int			err;
	DECLARE_COMPLETION_ONSTACK(done);

	newst = kzalloc(sizeof(struct mISDNstack), GFP_KERNEL);
	if (!newst) {
		printk(KERN_ERR "kmalloc mISDN_stack failed\n");
		return -ENOMEM;
	}
	newst->dev = dev;
	INIT_LIST_HEAD(&newst->layer2);
	INIT_HLIST_HEAD(&newst->l1sock.head);
	rwlock_init(&newst->l1sock.lock);
	init_waitqueue_head(&newst->workq);
	skb_queue_head_init(&newst->msgq);
	mutex_init(&newst->lmutex);
	dev->D.st = newst;
	err = create_teimanager(dev);
	if (err) {
		printk(KERN_ERR "kmalloc teimanager failed\n");
		kfree(newst);
		return err;
	}
	dev->teimgr->peer = &newst->own;
	dev->teimgr->recv = mISDN_queue_message;
	dev->teimgr->st = newst;
	newst->layer1 = &dev->D;
	dev->D.recv = l1_receive;
	dev->D.peer = &newst->own;
	newst->own.st = newst;
	newst->own.ctrl = st_own_ctrl;
	newst->own.send = mISDN_queue_message;
	newst->own.recv = mISDN_queue_message;
	if (*debug & DEBUG_CORE_FUNC)
		printk(KERN_DEBUG "%s: st(%s)\n", __func__,
		       dev_name(&newst->dev->dev));
	newst->notify = &done;
	newst->thread = kthread_run(mISDNStackd, (void *)newst, "mISDN_%s",
				    dev_name(&newst->dev->dev));
	if (IS_ERR(newst->thread)) {
		err = PTR_ERR(newst->thread);
		printk(KERN_ERR
		       "mISDN:cannot create kernel thread for %s (%d)\n",
		       dev_name(&newst->dev->dev), err);
		delete_teimanager(dev->teimgr);
		kfree(newst);
	} else
		wait_for_completion(&done);
	return err;
}

int
connect_layer1(struct mISDNdevice *dev, struct mISDNchannel *ch,
	       u_int protocol, struct sockaddr_mISDN *adr)
{
	struct mISDN_sock	*msk = container_of(ch, struct mISDN_sock, ch);
	struct channel_req	rq;
	int			err;


	if (*debug &  DEBUG_CORE_FUNC)
		printk(KERN_DEBUG "%s: %s proto(%x) adr(%d %d %d %d)\n",
		       __func__, dev_name(&dev->dev), protocol, adr->dev,
		       adr->channel, adr->sapi, adr->tei);
	switch (protocol) {
	case ISDN_P_NT_S0:
	case ISDN_P_NT_E1:
	case ISDN_P_TE_S0:
	case ISDN_P_TE_E1:
		ch->recv = mISDN_queue_message;
		ch->peer = &dev->D.st->own;
		ch->st = dev->D.st;
		rq.protocol = protocol;
		rq.adr.channel = adr->channel;
		err = dev->D.ctrl(&dev->D, OPEN_CHANNEL, &rq);
		printk(KERN_DEBUG "%s: ret %d (dev %d)\n", __func__, err,
		       dev->id);
		if (err)
			return err;
		write_lock_bh(&dev->D.st->l1sock.lock);
		sk_add_node(&msk->sk, &dev->D.st->l1sock.head);
		write_unlock_bh(&dev->D.st->l1sock.lock);
		break;
	default:
		return -ENOPROTOOPT;
	}
	return 0;
}

int
connect_Bstack(struct mISDNdevice *dev, struct mISDNchannel *ch,
	       u_int protocol, struct sockaddr_mISDN *adr)
{
	struct channel_req	rq, rq2;
	int			pmask, err;
	struct Bprotocol	*bp;

	if (*debug &  DEBUG_CORE_FUNC)
		printk(KERN_DEBUG "%s: %s proto(%x) adr(%d %d %d %d)\n",
		       __func__, dev_name(&dev->dev), protocol,
		       adr->dev, adr->channel, adr->sapi,
		       adr->tei);
	ch->st = dev->D.st;
	pmask = 1 << (protocol & ISDN_P_B_MASK);
	if (pmask & dev->Bprotocols) {
		rq.protocol = protocol;
		rq.adr = *adr;
		err = dev->D.ctrl(&dev->D, OPEN_CHANNEL, &rq);
		if (err)
			return err;
		ch->recv = rq.ch->send;
		ch->peer = rq.ch;
		rq.ch->recv = ch->send;
		rq.ch->peer = ch;
		rq.ch->st = dev->D.st;
	} else {
		bp = get_Bprotocol4mask(pmask);
		if (!bp)
			return -ENOPROTOOPT;
		rq2.protocol = protocol;
		rq2.adr = *adr;
		rq2.ch = ch;
		err = bp->create(&rq2);
		if (err)
			return err;
		ch->recv = rq2.ch->send;
		ch->peer = rq2.ch;
		rq2.ch->st = dev->D.st;
		rq.protocol = rq2.protocol;
		rq.adr = *adr;
		err = dev->D.ctrl(&dev->D, OPEN_CHANNEL, &rq);
		if (err) {
			rq2.ch->ctrl(rq2.ch, CLOSE_CHANNEL, NULL);
			return err;
		}
		rq2.ch->recv = rq.ch->send;
		rq2.ch->peer = rq.ch;
		rq.ch->recv = rq2.ch->send;
		rq.ch->peer = rq2.ch;
		rq.ch->st = dev->D.st;
	}
	ch->protocol = protocol;
	ch->nr = rq.ch->nr;
	return 0;
}

int
create_l2entity(struct mISDNdevice *dev, struct mISDNchannel *ch,
		u_int protocol, struct sockaddr_mISDN *adr)
{
	struct channel_req	rq;
	int			err;

	if (*debug &  DEBUG_CORE_FUNC)
		printk(KERN_DEBUG "%s: %s proto(%x) adr(%d %d %d %d)\n",
		       __func__, dev_name(&dev->dev), protocol,
		       adr->dev, adr->channel, adr->sapi,
		       adr->tei);
	rq.protocol = ISDN_P_TE_S0;
	if (dev->Dprotocols & (1 << ISDN_P_TE_E1))
		rq.protocol = ISDN_P_TE_E1;
	switch (protocol) {
	case ISDN_P_LAPD_NT:
		rq.protocol = ISDN_P_NT_S0;
		if (dev->Dprotocols & (1 << ISDN_P_NT_E1))
			rq.protocol = ISDN_P_NT_E1;
		/* fall through */
	case ISDN_P_LAPD_TE:
		ch->recv = mISDN_queue_message;
		ch->peer = &dev->D.st->own;
		ch->st = dev->D.st;
		rq.adr.channel = 0;
		err = dev->D.ctrl(&dev->D, OPEN_CHANNEL, &rq);
		printk(KERN_DEBUG "%s: ret 1 %d\n", __func__, err);
		if (err)
			break;
		rq.protocol = protocol;
		rq.adr = *adr;
		rq.ch = ch;
		err = dev->teimgr->ctrl(dev->teimgr, OPEN_CHANNEL, &rq);
		printk(KERN_DEBUG "%s: ret 2 %d\n", __func__, err);
		if (!err) {
			if ((protocol == ISDN_P_LAPD_NT) && !rq.ch)
				break;
			add_layer2(rq.ch, dev->D.st);
			rq.ch->recv = mISDN_queue_message;
			rq.ch->peer = &dev->D.st->own;
			rq.ch->ctrl(rq.ch, OPEN_CHANNEL, NULL); /* can't fail */
		}
		break;
	default:
		err = -EPROTONOSUPPORT;
	}
	return err;
}

void
delete_channel(struct mISDNchannel *ch)
{
	struct mISDN_sock	*msk = container_of(ch, struct mISDN_sock, ch);
	struct mISDNchannel	*pch;

	if (!ch->st) {
		printk(KERN_WARNING "%s: no stack\n", __func__);
		return;
	}
	if (*debug & DEBUG_CORE_FUNC)
		printk(KERN_DEBUG "%s: st(%s) protocol(%x)\n", __func__,
		       dev_name(&ch->st->dev->dev), ch->protocol);
	if (ch->protocol >= ISDN_P_B_START) {
		if (ch->peer) {
			ch->peer->ctrl(ch->peer, CLOSE_CHANNEL, NULL);
			ch->peer = NULL;
		}
		return;
	}
	switch (ch->protocol) {
	case ISDN_P_NT_S0:
	case ISDN_P_TE_S0:
	case ISDN_P_NT_E1:
	case ISDN_P_TE_E1:
		write_lock_bh(&ch->st->l1sock.lock);
		sk_del_node_init(&msk->sk);
		write_unlock_bh(&ch->st->l1sock.lock);
		ch->st->dev->D.ctrl(&ch->st->dev->D, CLOSE_CHANNEL, NULL);
		break;
	case ISDN_P_LAPD_TE:
		pch = get_channel4id(ch->st, ch->nr);
		if (pch) {
			mutex_lock(&ch->st->lmutex);
			list_del(&pch->list);
			mutex_unlock(&ch->st->lmutex);
			pch->ctrl(pch, CLOSE_CHANNEL, NULL);
			pch = ch->st->dev->teimgr;
			pch->ctrl(pch, CLOSE_CHANNEL, NULL);
		} else
			printk(KERN_WARNING "%s: no l2 channel\n",
			       __func__);
		break;
	case ISDN_P_LAPD_NT:
		pch = ch->st->dev->teimgr;
		if (pch) {
			pch->ctrl(pch, CLOSE_CHANNEL, NULL);
		} else
			printk(KERN_WARNING "%s: no l2 channel\n",
			       __func__);
		break;
	default:
		break;
	}
	return;
}

void
delete_stack(struct mISDNdevice *dev)
{
	struct mISDNstack	*st = dev->D.st;
	DECLARE_COMPLETION_ONSTACK(done);

	if (*debug & DEBUG_CORE_FUNC)
		printk(KERN_DEBUG "%s: st(%s)\n", __func__,
		       dev_name(&st->dev->dev));
	if (dev->teimgr)
		delete_teimanager(dev->teimgr);
	if (st->thread) {
		if (st->notify) {
			printk(KERN_WARNING "%s: notifier in use\n",
			       __func__);
			complete(st->notify);
		}
		st->notify = &done;
		test_and_set_bit(mISDN_STACK_ABORT, &st->status);
		test_and_set_bit(mISDN_STACK_WAKEUP, &st->status);
		wake_up_interruptible(&st->workq);
		wait_for_completion(&done);
	}
	if (!list_empty(&st->layer2))
		printk(KERN_WARNING "%s: layer2 list not empty\n",
		       __func__);
	if (!hlist_empty(&st->l1sock.head))
		printk(KERN_WARNING "%s: layer1 list not empty\n",
		       __func__);
	kfree(st);
}

void
mISDN_initstack(u_int *dp)
{
	debug = dp;
}