[linux.git] / net / caif / caif_dev.c

/*
 * CAIF Interface registration.
 * Copyright (C) ST-Ericsson AB 2010
 * Author:	Sjur Brendeland
 * License terms: GNU General Public License (GPL) version 2
 *
 * Borrowed heavily from file: pn_dev.c. Thanks to Remi Denis-Courmont
 *  and Sakari Ailus <[email protected]>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__

#include <linux/kernel.h>
#include <linux/if_arp.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/mutex.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <net/netns/generic.h>
#include <net/net_namespace.h>
#include <net/pkt_sched.h>
#include <net/caif/caif_device.h>
#include <net/caif/caif_layer.h>
#include <net/caif/cfpkt.h>
#include <net/caif/cfcnfg.h>
#include <net/caif/cfserl.h>

MODULE_LICENSE("GPL");

/* Used for local tracking of the CAIF net devices */
struct caif_device_entry {
	struct cflayer layer;
	struct list_head list;
	struct net_device *netdev;
	int __percpu *pcpu_refcnt;
	spinlock_t flow_lock;
	struct sk_buff *xoff_skb;
	void (*xoff_skb_dtor)(struct sk_buff *skb);
	bool xoff;
};

struct caif_device_entry_list {
	struct list_head list;
	/* Protects simulanous deletes in list */
	struct mutex lock;
};

struct caif_net {
	struct cfcnfg *cfg;
	struct caif_device_entry_list caifdevs;
};

static int caif_net_id;
static int q_high = 50; /* Percent */

struct cfcnfg *get_cfcnfg(struct net *net)
{
	struct caif_net *caifn;
	caifn = net_generic(net, caif_net_id);
	return caifn->cfg;
}
EXPORT_SYMBOL(get_cfcnfg);

static struct caif_device_entry_list *caif_device_list(struct net *net)
{
	struct caif_net *caifn;
	caifn = net_generic(net, caif_net_id);
	return &caifn->caifdevs;
}

static void caifd_put(struct caif_device_entry *e)
{
	this_cpu_dec(*e->pcpu_refcnt);
}

static void caifd_hold(struct caif_device_entry *e)
{
	this_cpu_inc(*e->pcpu_refcnt);
}

static int caifd_refcnt_read(struct caif_device_entry *e)
{
	int i, refcnt = 0;
	for_each_possible_cpu(i)
		refcnt += *per_cpu_ptr(e->pcpu_refcnt, i);
	return refcnt;
}

/* Allocate new CAIF device. */
static struct caif_device_entry *caif_device_alloc(struct net_device *dev)
{
	struct caif_device_entry *caifd;

	caifd = kzalloc(sizeof(*caifd), GFP_KERNEL);
	if (!caifd)
		return NULL;
	caifd->pcpu_refcnt = alloc_percpu(int);
	if (!caifd->pcpu_refcnt) {
		kfree(caifd);
		return NULL;
	}
	caifd->netdev = dev;
	dev_hold(dev);
	return caifd;
}

static struct caif_device_entry *caif_get(struct net_device *dev)
{
	struct caif_device_entry_list *caifdevs =
	    caif_device_list(dev_net(dev));
	struct caif_device_entry *caifd;

	list_for_each_entry_rcu(caifd, &caifdevs->list, list) {
		if (caifd->netdev == dev)
			return caifd;
	}
	return NULL;
}

static void caif_flow_cb(struct sk_buff *skb)
{
	struct caif_device_entry *caifd;
	void (*dtor)(struct sk_buff *skb) = NULL;
	bool send_xoff;

	WARN_ON(skb->dev == NULL);

	rcu_read_lock();
	caifd = caif_get(skb->dev);

	WARN_ON(caifd == NULL);
	if (caifd == NULL)
		return;

	caifd_hold(caifd);
	rcu_read_unlock();

	spin_lock_bh(&caifd->flow_lock);
	send_xoff = caifd->xoff;
	caifd->xoff = 0;
	dtor = caifd->xoff_skb_dtor;

	if (WARN_ON(caifd->xoff_skb != skb))
		skb = NULL;

	caifd->xoff_skb = NULL;
	caifd->xoff_skb_dtor = NULL;

	spin_unlock_bh(&caifd->flow_lock);

	if (dtor && skb)
		dtor(skb);

	if (send_xoff)
		caifd->layer.up->
			ctrlcmd(caifd->layer.up,
				_CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
				caifd->layer.id);
	caifd_put(caifd);
}

static int transmit(struct cflayer *layer, struct cfpkt *pkt)
{
	int err, high = 0, qlen = 0;
	struct caif_device_entry *caifd =
	    container_of(layer, struct caif_device_entry, layer);
	struct sk_buff *skb;
	struct netdev_queue *txq;

	rcu_read_lock_bh();

	skb = cfpkt_tonative(pkt);
	skb->dev = caifd->netdev;
	skb_reset_network_header(skb);
	skb->protocol = htons(ETH_P_CAIF);

	/* Check if we need to handle xoff */
	if (likely(caifd->netdev->tx_queue_len == 0))
		goto noxoff;

	if (unlikely(caifd->xoff))
		goto noxoff;

	if (likely(!netif_queue_stopped(caifd->netdev))) {
		/* If we run with a TX queue, check if the queue is too long*/
		txq = netdev_get_tx_queue(skb->dev, 0);
		qlen = qdisc_qlen(rcu_dereference_bh(txq->qdisc));

		if (likely(qlen == 0))
			goto noxoff;

		high = (caifd->netdev->tx_queue_len * q_high) / 100;
		if (likely(qlen < high))
			goto noxoff;
	}

	/* Hold lock while accessing xoff */
	spin_lock_bh(&caifd->flow_lock);
	if (caifd->xoff) {
		spin_unlock_bh(&caifd->flow_lock);
		goto noxoff;
	}

	/*
	 * Handle flow off, we do this by temporary hi-jacking this
	 * skb's destructor function, and replace it with our own
	 * flow-on callback. The callback will set flow-on and call
	 * the original destructor.
	 */

	pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
			netif_queue_stopped(caifd->netdev),
			qlen, high);
	caifd->xoff = 1;
	caifd->xoff_skb = skb;
	caifd->xoff_skb_dtor = skb->destructor;
	skb->destructor = caif_flow_cb;
	spin_unlock_bh(&caifd->flow_lock);

	caifd->layer.up->ctrlcmd(caifd->layer.up,
					_CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
					caifd->layer.id);
noxoff:
	rcu_read_unlock_bh();

	err = dev_queue_xmit(skb);
	if (err > 0)
		err = -EIO;

	return err;
}

/*
 * Stuff received packets into the CAIF stack.
 * On error, returns non-zero and releases the skb.
 */
static int receive(struct sk_buff *skb, struct net_device *dev,
		   struct packet_type *pkttype, struct net_device *orig_dev)
{
	struct cfpkt *pkt;
	struct caif_device_entry *caifd;
	int err;

	pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);

	rcu_read_lock();
	caifd = caif_get(dev);

	if (!caifd || !caifd->layer.up || !caifd->layer.up->receive ||
			!netif_oper_up(caifd->netdev)) {
		rcu_read_unlock();
		kfree_skb(skb);
		return NET_RX_DROP;
	}

	/* Hold reference to netdevice while using CAIF stack */
	caifd_hold(caifd);
	rcu_read_unlock();

	err = caifd->layer.up->receive(caifd->layer.up, pkt);

	/* For -EILSEQ the packet is not freed so so it now */
	if (err == -EILSEQ)
		cfpkt_destroy(pkt);

	/* Release reference to stack upwards */
	caifd_put(caifd);

	if (err != 0)
		err = NET_RX_DROP;
	return err;
}

static struct packet_type caif_packet_type __read_mostly = {
	.type = cpu_to_be16(ETH_P_CAIF),
	.func = receive,
};

static void dev_flowctrl(struct net_device *dev, int on)
{
	struct caif_device_entry *caifd;

	rcu_read_lock();

	caifd = caif_get(dev);
	if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
		rcu_read_unlock();
		return;
	}

	caifd_hold(caifd);
	rcu_read_unlock();

	caifd->layer.up->ctrlcmd(caifd->layer.up,
				 on ?
				 _CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
				 _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
				 caifd->layer.id);
	caifd_put(caifd);
}

void caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
		     struct cflayer *link_support, int head_room,
		     struct cflayer **layer,
		     int (**rcv_func)(struct sk_buff *, struct net_device *,
				      struct packet_type *,
				      struct net_device *))
{
	struct caif_device_entry *caifd;
	enum cfcnfg_phy_preference pref;
	struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
	struct caif_device_entry_list *caifdevs;

	caifdevs = caif_device_list(dev_net(dev));
	caifd = caif_device_alloc(dev);
	if (!caifd)
		return;
	*layer = &caifd->layer;
	spin_lock_init(&caifd->flow_lock);

	switch (caifdev->link_select) {
	case CAIF_LINK_HIGH_BANDW:
		pref = CFPHYPREF_HIGH_BW;
		break;
	case CAIF_LINK_LOW_LATENCY:
		pref = CFPHYPREF_LOW_LAT;
		break;
	default:
		pref = CFPHYPREF_HIGH_BW;
		break;
	}
	mutex_lock(&caifdevs->lock);
	list_add_rcu(&caifd->list, &caifdevs->list);

	strncpy(caifd->layer.name, dev->name,
		sizeof(caifd->layer.name) - 1);
	caifd->layer.name[sizeof(caifd->layer.name) - 1] = 0;
	caifd->layer.transmit = transmit;
	cfcnfg_add_phy_layer(cfg,
				dev,
				&caifd->layer,
				pref,
				link_support,
				caifdev->use_fcs,
				head_room);
	mutex_unlock(&caifdevs->lock);
	if (rcv_func)
		*rcv_func = receive;
}
EXPORT_SYMBOL(caif_enroll_dev);

/* notify Caif of device events */
static int caif_device_notify(struct notifier_block *me, unsigned long what,
			      void *ptr)
{
	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
	struct caif_device_entry *caifd = NULL;
	struct caif_dev_common *caifdev;
	struct cfcnfg *cfg;
	struct cflayer *layer, *link_support;
	int head_room = 0;
	struct caif_device_entry_list *caifdevs;

	cfg = get_cfcnfg(dev_net(dev));
	caifdevs = caif_device_list(dev_net(dev));

	caifd = caif_get(dev);
	if (caifd == NULL && dev->type != ARPHRD_CAIF)
		return 0;

	switch (what) {
	case NETDEV_REGISTER:
		if (caifd != NULL)
			break;

		caifdev = netdev_priv(dev);

		link_support = NULL;
		if (caifdev->use_frag) {
			head_room = 1;
			link_support = cfserl_create(dev->ifindex,
							caifdev->use_stx);
			if (!link_support) {
				pr_warn("Out of memory\n");
				break;
			}
		}
		caif_enroll_dev(dev, caifdev, link_support, head_room,
				&layer, NULL);
		caifdev->flowctrl = dev_flowctrl;
		break;

	case NETDEV_UP:
		rcu_read_lock();

		caifd = caif_get(dev);
		if (caifd == NULL) {
			rcu_read_unlock();
			break;
		}

		caifd->xoff = 0;
		cfcnfg_set_phy_state(cfg, &caifd->layer, true);
		rcu_read_unlock();

		break;

	case NETDEV_DOWN:
		rcu_read_lock();

		caifd = caif_get(dev);
		if (!caifd || !caifd->layer.up || !caifd->layer.up->ctrlcmd) {
			rcu_read_unlock();
			return -EINVAL;
		}

		cfcnfg_set_phy_state(cfg, &caifd->layer, false);
		caifd_hold(caifd);
		rcu_read_unlock();

		caifd->layer.up->ctrlcmd(caifd->layer.up,
					 _CAIF_CTRLCMD_PHYIF_DOWN_IND,
					 caifd->layer.id);

		spin_lock_bh(&caifd->flow_lock);

		/*
		 * Replace our xoff-destructor with original destructor.
		 * We trust that skb->destructor *always* is called before
		 * the skb reference is invalid. The hijacked SKB destructor
		 * takes the flow_lock so manipulating the skb->destructor here
		 * should be safe.
		*/
		if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
			caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;

		caifd->xoff = 0;
		caifd->xoff_skb_dtor = NULL;
		caifd->xoff_skb = NULL;

		spin_unlock_bh(&caifd->flow_lock);
		caifd_put(caifd);
		break;

	case NETDEV_UNREGISTER:
		mutex_lock(&caifdevs->lock);

		caifd = caif_get(dev);
		if (caifd == NULL) {
			mutex_unlock(&caifdevs->lock);
			break;
		}
		list_del_rcu(&caifd->list);

		/*
		 * NETDEV_UNREGISTER is called repeatedly until all reference
		 * counts for the net-device are released. If references to
		 * caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
		 * the next call to NETDEV_UNREGISTER.
		 *
		 * If any packets are in flight down the CAIF Stack,
		 * cfcnfg_del_phy_layer will return nonzero.
		 * If no packets are in flight, the CAIF Stack associated
		 * with the net-device un-registering is freed.
		 */

		if (caifd_refcnt_read(caifd) != 0 ||
			cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {

			pr_info("Wait for device inuse\n");
			/* Enrole device if CAIF Stack is still in use */
			list_add_rcu(&caifd->list, &caifdevs->list);
			mutex_unlock(&caifdevs->lock);
			break;
		}

		synchronize_rcu();
		dev_put(caifd->netdev);
		free_percpu(caifd->pcpu_refcnt);
		kfree(caifd);

		mutex_unlock(&caifdevs->lock);
		break;
	}
	return 0;
}

static struct notifier_block caif_device_notifier = {
	.notifier_call = caif_device_notify,
	.priority = 0,
};

/* Per-namespace Caif devices handling */
static int caif_init_net(struct net *net)
{
	struct caif_net *caifn = net_generic(net, caif_net_id);
	INIT_LIST_HEAD(&caifn->caifdevs.list);
	mutex_init(&caifn->caifdevs.lock);

	caifn->cfg = cfcnfg_create();
	if (!caifn->cfg)
		return -ENOMEM;

	return 0;
}

static void caif_exit_net(struct net *net)
{
	struct caif_device_entry *caifd, *tmp;
	struct caif_device_entry_list *caifdevs =
	    caif_device_list(net);
	struct cfcnfg *cfg =  get_cfcnfg(net);

	rtnl_lock();
	mutex_lock(&caifdevs->lock);

	list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
		int i = 0;
		list_del_rcu(&caifd->list);
		cfcnfg_set_phy_state(cfg, &caifd->layer, false);

		while (i < 10 &&
			(caifd_refcnt_read(caifd) != 0 ||
			cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {

			pr_info("Wait for device inuse\n");
			msleep(250);
			i++;
		}
		synchronize_rcu();
		dev_put(caifd->netdev);
		free_percpu(caifd->pcpu_refcnt);
		kfree(caifd);
	}
	cfcnfg_remove(cfg);

	mutex_unlock(&caifdevs->lock);
	rtnl_unlock();
}

static struct pernet_operations caif_net_ops = {
	.init = caif_init_net,
	.exit = caif_exit_net,
	.id   = &caif_net_id,
	.size = sizeof(struct caif_net),
};

/* Initialize Caif devices list */
static int __init caif_device_init(void)
{
	int result;

	result = register_pernet_subsys(&caif_net_ops);

	if (result)
		return result;

	register_netdevice_notifier(&caif_device_notifier);
	dev_add_pack(&caif_packet_type);

	return result;
}

static void __exit caif_device_exit(void)
{
	unregister_netdevice_notifier(&caif_device_notifier);
	dev_remove_pack(&caif_packet_type);
	unregister_pernet_subsys(&caif_net_ops);
}

module_init(caif_device_init);
module_exit(caif_device_exit);
Commit	Line	Data
c72dfae2 SB	1	/*
	2	* CAIF Interface registration.
	3	* Copyright (C) ST-Ericsson AB 2010
26ee65e6	4	* Author: Sjur Brendeland
c72dfae2 SB	5	* License terms: GNU General Public License (GPL) version 2
c72dfae2 SB	6	*
31fdc555	7	* Borrowed heavily from file: pn_dev.c. Thanks to Remi Denis-Courmont
c72dfae2 SB	8	* and Sakari Ailus <[email protected]>
	9	*/
	10
b31fa5ba JP	11	#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
b31fa5ba JP	12
c72dfae2 SB	13	#include <linux/kernel.h>
	14	#include <linux/if_arp.h>
	15	#include <linux/net.h>
	16	#include <linux/netdevice.h>
bd30ce4b	17	#include <linux/mutex.h>
3a9a231d	18	#include <linux/module.h>
0e4c7d85	19	#include <linux/spinlock.h>
c72dfae2 SB	20	#include <net/netns/generic.h>
	21	#include <net/net_namespace.h>
	22	#include <net/pkt_sched.h>
	23	#include <net/caif/caif_device.h>
c72dfae2 SB	24	#include <net/caif/caif_layer.h>
	25	#include <net/caif/cfpkt.h>
	26	#include <net/caif/cfcnfg.h>
7c18d220	27	#include <net/caif/cfserl.h>
c72dfae2 SB	28
c72dfae2 SB	29	MODULE_LICENSE("GPL");
c72dfae2 SB	30
	31	/* Used for local tracking of the CAIF net devices */
	32	struct caif_device_entry {
	33	struct cflayer layer;
	34	struct list_head list;
c72dfae2	35	struct net_device *netdev;
bd30ce4b	36	int __percpu *pcpu_refcnt;
0e4c7d85	37	spinlock_t flow_lock;
7d311304	38	struct sk_buff *xoff_skb;
7d311304	39	void (xoff_skb_dtor)(struct sk_buff skb);
0e4c7d85	40	bool xoff;
c72dfae2 SB	41	};
	42
	43	struct caif_device_entry_list {
	44	struct list_head list;
	45	/* Protects simulanous deletes in list */
bd30ce4b	46	struct mutex lock;
c72dfae2 SB	47	};
	48
	49	struct caif_net {
bee925db	50	struct cfcnfg *cfg;
c72dfae2 SB	51	struct caif_device_entry_list caifdevs;
	52	};
	53
	54	static int caif_net_id;
0e4c7d85	55	static int q_high = 50; /* Percent */
bee925db	56
	57	struct cfcnfg get_cfcnfg(struct net net)
	58	{
	59	struct caif_net *caifn;
bee925db	60	caifn = net_generic(net, caif_net_id);
bee925db	61	return caifn->cfg;
	62	}
	63	EXPORT_SYMBOL(get_cfcnfg);
c72dfae2 SB	64
	65	static struct caif_device_entry_list caif_device_list(struct net net)
	66	{
	67	struct caif_net *caifn;
c72dfae2	68	caifn = net_generic(net, caif_net_id);
c72dfae2 SB	69	return &caifn->caifdevs;
	70	}
	71
bd30ce4b	72	static void caifd_put(struct caif_device_entry *e)
bd30ce4b	73	{
933393f5	74	this_cpu_dec(*e->pcpu_refcnt);
bd30ce4b	75	}
	76
	77	static void caifd_hold(struct caif_device_entry *e)
	78	{
933393f5	79	this_cpu_inc(*e->pcpu_refcnt);
bd30ce4b	80	}
	81
	82	static int caifd_refcnt_read(struct caif_device_entry *e)
	83	{
	84	int i, refcnt = 0;
	85	for_each_possible_cpu(i)
	86	refcnt += *per_cpu_ptr(e->pcpu_refcnt, i);
	87	return refcnt;
	88	}
	89
c72dfae2 SB	90	/* Allocate new CAIF device. */
	91	static struct caif_device_entry caif_device_alloc(struct net_device dev)
	92	{
c72dfae2	93	struct caif_device_entry *caifd;
bd30ce4b	94
4fb66b82	95	caifd = kzalloc(sizeof(*caifd), GFP_KERNEL);
c72dfae2 SB	96	if (!caifd)
c72dfae2 SB	97	return NULL;
bd30ce4b	98	caifd->pcpu_refcnt = alloc_percpu(int);
4fb66b82 ED	99	if (!caifd->pcpu_refcnt) {
	100	kfree(caifd);
	101	return NULL;
	102	}
c72dfae2	103	caifd->netdev = dev;
bd30ce4b	104	dev_hold(dev);
c72dfae2 SB	105	return caifd;
	106	}
	107
	108	static struct caif_device_entry caif_get(struct net_device dev)
	109	{
	110	struct caif_device_entry_list *caifdevs =
	111	caif_device_list(dev_net(dev));
	112	struct caif_device_entry *caifd;
7c18d220	113
bd30ce4b	114	list_for_each_entry_rcu(caifd, &caifdevs->list, list) {
c72dfae2 SB	115	if (caifd->netdev == dev)
	116	return caifd;
	117	}
	118	return NULL;
	119	}
	120
d6e89c0b	121	static void caif_flow_cb(struct sk_buff *skb)
0e4c7d85	122	{
0e4c7d85	123	struct caif_device_entry *caifd;
7d311304	124	void (dtor)(struct sk_buff skb) = NULL;
0e4c7d85	125	bool send_xoff;
	126
	127	WARN_ON(skb->dev == NULL);
	128
	129	rcu_read_lock();
	130	caifd = caif_get(skb->dev);
c95567c8 KLX	131
	132	WARN_ON(caifd == NULL);
	133	if (caifd == NULL)
	134	return;
	135
0e4c7d85	136	caifd_hold(caifd);
	137	rcu_read_unlock();
	138
	139	spin_lock_bh(&caifd->flow_lock);
	140	send_xoff = caifd->xoff;
	141	caifd->xoff = 0;
59f608d8	142	dtor = caifd->xoff_skb_dtor;
	143
	144	if (WARN_ON(caifd->xoff_skb != skb))
	145	skb = NULL;
	146
	147	caifd->xoff_skb = NULL;
	148	caifd->xoff_skb_dtor = NULL;
	149
0e4c7d85	150	spin_unlock_bh(&caifd->flow_lock);
0e4c7d85	151
59f608d8	152	if (dtor && skb)
7d311304	153	dtor(skb);
7d311304	154
0e4c7d85	155	if (send_xoff)
	156	caifd->layer.up->
	157	ctrlcmd(caifd->layer.up,
	158	_CAIF_CTRLCMD_PHYIF_FLOW_ON_IND,
	159	caifd->layer.id);
	160	caifd_put(caifd);
	161	}
	162
c72dfae2 SB	163	static int transmit(struct cflayer layer, struct cfpkt pkt)
c72dfae2 SB	164	{
0e4c7d85	165	int err, high = 0, qlen = 0;
c72dfae2 SB	166	struct caif_device_entry *caifd =
c72dfae2 SB	167	container_of(layer, struct caif_device_entry, layer);
4dd820c0	168	struct sk_buff *skb;
0e4c7d85	169	struct netdev_queue *txq;
	170
	171	rcu_read_lock_bh();
4dd820c0	172
c72dfae2 SB	173	skb = cfpkt_tonative(pkt);
c72dfae2 SB	174	skb->dev = caifd->netdev;
7c18d220	175	skb_reset_network_header(skb);
7c18d220	176	skb->protocol = htons(ETH_P_CAIF);
0e4c7d85	177
	178	/* Check if we need to handle xoff */
	179	if (likely(caifd->netdev->tx_queue_len == 0))
	180	goto noxoff;
	181
	182	if (unlikely(caifd->xoff))
	183	goto noxoff;
	184
	185	if (likely(!netif_queue_stopped(caifd->netdev))) {
	186	/* If we run with a TX queue, check if the queue is too long*/
	187	txq = netdev_get_tx_queue(skb->dev, 0);
	188	qlen = qdisc_qlen(rcu_dereference_bh(txq->qdisc));
	189
	190	if (likely(qlen == 0))
	191	goto noxoff;
	192
	193	high = (caifd->netdev->tx_queue_len * q_high) / 100;
	194	if (likely(qlen < high))
	195	goto noxoff;
	196	}
	197
	198	/* Hold lock while accessing xoff */
	199	spin_lock_bh(&caifd->flow_lock);
	200	if (caifd->xoff) {
	201	spin_unlock_bh(&caifd->flow_lock);
	202	goto noxoff;
	203	}
	204
	205	/*
	206	* Handle flow off, we do this by temporary hi-jacking this
	207	* skb's destructor function, and replace it with our own
	208	* flow-on callback. The callback will set flow-on and call
	209	* the original destructor.
	210	*/
	211
	212	pr_debug("queue has stopped(%d) or is full (%d > %d)\n",
	213	netif_queue_stopped(caifd->netdev),
	214	qlen, high);
	215	caifd->xoff = 1;
7d311304	216	caifd->xoff_skb = skb;
	217	caifd->xoff_skb_dtor = skb->destructor;
	218	skb->destructor = caif_flow_cb;
0e4c7d85	219	spin_unlock_bh(&caifd->flow_lock);
0e4c7d85	220
	221	caifd->layer.up->ctrlcmd(caifd->layer.up,
	222	_CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
	223	caifd->layer.id);
	224	noxoff:
	225	rcu_read_unlock_bh();
4dd820c0	226
c85c2951	227	err = dev_queue_xmit(skb);
	228	if (err > 0)
	229	err = -EIO;
c72dfae2	230
c85c2951	231	return err;
c72dfae2 SB	232	}
c72dfae2 SB	233
c72dfae2	234	/*
bd30ce4b	235	* Stuff received packets into the CAIF stack.
c72dfae2 SB	236	* On error, returns non-zero and releases the skb.
	237	*/
	238	static int receive(struct sk_buff skb, struct net_device dev,
	239	struct packet_type pkttype, struct net_device orig_dev)
	240	{
c72dfae2 SB	241	struct cfpkt *pkt;
c72dfae2 SB	242	struct caif_device_entry *caifd;
69c867c9	243	int err;
bd30ce4b	244
c72dfae2	245	pkt = cfpkt_fromnative(CAIF_DIR_IN, skb);
bd30ce4b	246
bd30ce4b	247	rcu_read_lock();
c72dfae2	248	caifd = caif_get(dev);
c72dfae2	249
bd30ce4b	250	if (!caifd \|\| !caifd->layer.up \|\| !caifd->layer.up->receive \|\|
	251	!netif_oper_up(caifd->netdev)) {
	252	rcu_read_unlock();
	253	kfree_skb(skb);
c72dfae2	254	return NET_RX_DROP;
bd30ce4b	255	}
	256
	257	/* Hold reference to netdevice while using CAIF stack */
	258	caifd_hold(caifd);
	259	rcu_read_unlock();
c72dfae2	260
69c867c9	261	err = caifd->layer.up->receive(caifd->layer.up, pkt);
	262
	263	/* For -EILSEQ the packet is not freed so so it now */
	264	if (err == -EILSEQ)
	265	cfpkt_destroy(pkt);
bd30ce4b	266
	267	/* Release reference to stack upwards */
	268	caifd_put(caifd);
7c18d220	269
	270	if (err != 0)
	271	err = NET_RX_DROP;
	272	return err;
c72dfae2 SB	273	}
	274
	275	static struct packet_type caif_packet_type __read_mostly = {
	276	.type = cpu_to_be16(ETH_P_CAIF),
	277	.func = receive,
	278	};
	279
	280	static void dev_flowctrl(struct net_device *dev, int on)
	281	{
bd30ce4b	282	struct caif_device_entry *caifd;
	283
	284	rcu_read_lock();
	285
	286	caifd = caif_get(dev);
	287	if (!caifd \|\| !caifd->layer.up \|\| !caifd->layer.up->ctrlcmd) {
	288	rcu_read_unlock();
c72dfae2	289	return;
bd30ce4b	290	}
	291
	292	caifd_hold(caifd);
	293	rcu_read_unlock();
c72dfae2 SB	294
	295	caifd->layer.up->ctrlcmd(caifd->layer.up,
	296	on ?
	297	_CAIF_CTRLCMD_PHYIF_FLOW_ON_IND :
	298	_CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND,
	299	caifd->layer.id);
bd30ce4b	300	caifd_put(caifd);
c72dfae2 SB	301	}
c72dfae2 SB	302
7c18d220	303	void caif_enroll_dev(struct net_device dev, struct caif_dev_common caifdev,
3bffc475 SMP	304	struct cflayer *link_support, int head_room,
	305	struct cflayer **layer,
	306	int (*rcv_func)(struct sk_buff , struct net_device *,
	307	struct packet_type *,
	308	struct net_device *))
7c18d220	309	{
	310	struct caif_device_entry *caifd;
	311	enum cfcnfg_phy_preference pref;
	312	struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
	313	struct caif_device_entry_list *caifdevs;
	314
	315	caifdevs = caif_device_list(dev_net(dev));
7c18d220	316	caifd = caif_device_alloc(dev);
	317	if (!caifd)
	318	return;
	319	*layer = &caifd->layer;
0e4c7d85	320	spin_lock_init(&caifd->flow_lock);
7c18d220	321
	322	switch (caifdev->link_select) {
	323	case CAIF_LINK_HIGH_BANDW:
	324	pref = CFPHYPREF_HIGH_BW;
	325	break;
	326	case CAIF_LINK_LOW_LATENCY:
	327	pref = CFPHYPREF_LOW_LAT;
	328	break;
	329	default:
	330	pref = CFPHYPREF_HIGH_BW;
	331	break;
	332	}
	333	mutex_lock(&caifdevs->lock);
	334	list_add_rcu(&caifd->list, &caifdevs->list);
	335
	336	strncpy(caifd->layer.name, dev->name,
	337	sizeof(caifd->layer.name) - 1);
	338	caifd->layer.name[sizeof(caifd->layer.name) - 1] = 0;
	339	caifd->layer.transmit = transmit;
	340	cfcnfg_add_phy_layer(cfg,
	341	dev,
	342	&caifd->layer,
	343	pref,
	344	link_support,
	345	caifdev->use_fcs,
	346	head_room);
	347	mutex_unlock(&caifdevs->lock);
	348	if (rcv_func)
	349	*rcv_func = receive;
	350	}
7ad65bf6	351	EXPORT_SYMBOL(caif_enroll_dev);
7c18d220	352
c72dfae2 SB	353	/* notify Caif of device events */
c72dfae2 SB	354	static int caif_device_notify(struct notifier_block *me, unsigned long what,
351638e7	355	void *ptr)
c72dfae2	356	{
351638e7	357	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
c72dfae2 SB	358	struct caif_device_entry *caifd = NULL;
c72dfae2 SB	359	struct caif_dev_common *caifdev;
bee925db	360	struct cfcnfg *cfg;
7c18d220	361	struct cflayer layer, link_support;
7c18d220	362	int head_room = 0;
08613e46	363	struct caif_device_entry_list *caifdevs;
c72dfae2	364
bee925db	365	cfg = get_cfcnfg(dev_net(dev));
7c18d220	366	caifdevs = caif_device_list(dev_net(dev));
bee925db	367
7c18d220	368	caifd = caif_get(dev);
	369	if (caifd == NULL && dev->type != ARPHRD_CAIF)
	370	return 0;
08613e46	371
c72dfae2 SB	372	switch (what) {
c72dfae2 SB	373	case NETDEV_REGISTER:
7c18d220	374	if (caifd != NULL)
7c18d220	375	break;
bd30ce4b	376
c72dfae2	377	caifdev = netdev_priv(dev);
c72dfae2	378
7c18d220	379	link_support = NULL;
	380	if (caifdev->use_frag) {
	381	head_room = 1;
	382	link_support = cfserl_create(dev->ifindex,
e977b4cf	383	caifdev->use_stx);
7c18d220	384	if (!link_support) {
	385	pr_warn("Out of memory\n");
	386	break;
	387	}
c72dfae2	388	}
7c18d220	389	caif_enroll_dev(dev, caifdev, link_support, head_room,
	390	&layer, NULL);
	391	caifdev->flowctrl = dev_flowctrl;
c72dfae2 SB	392	break;
c72dfae2 SB	393
bd30ce4b	394	case NETDEV_UP:
	395	rcu_read_lock();
	396
c72dfae2	397	caifd = caif_get(dev);
bd30ce4b	398	if (caifd == NULL) {
bd30ce4b	399	rcu_read_unlock();
c72dfae2	400	break;
bd30ce4b	401	}
c72dfae2	402
0e4c7d85	403	caifd->xoff = 0;
bd30ce4b	404	cfcnfg_set_phy_state(cfg, &caifd->layer, true);
bd30ce4b	405	rcu_read_unlock();
c72dfae2	406
c72dfae2 SB	407	break;
	408
	409	case NETDEV_DOWN:
bd30ce4b	410	rcu_read_lock();
bd30ce4b	411
c72dfae2	412	caifd = caif_get(dev);
bd30ce4b	413	if (!caifd \|\| !caifd->layer.up \|\| !caifd->layer.up->ctrlcmd) {
	414	rcu_read_unlock();
	415	return -EINVAL;
	416	}
	417
	418	cfcnfg_set_phy_state(cfg, &caifd->layer, false);
	419	caifd_hold(caifd);
	420	rcu_read_unlock();
	421
	422	caifd->layer.up->ctrlcmd(caifd->layer.up,
	423	_CAIF_CTRLCMD_PHYIF_DOWN_IND,
	424	caifd->layer.id);
7d311304	425
	426	spin_lock_bh(&caifd->flow_lock);
	427
	428	/*
	429	* Replace our xoff-destructor with original destructor.
	430	* We trust that skb->destructor always is called before
	431	* the skb reference is invalid. The hijacked SKB destructor
	432	* takes the flow_lock so manipulating the skb->destructor here
	433	* should be safe.
	434	*/
	435	if (caifd->xoff_skb_dtor != NULL && caifd->xoff_skb != NULL)
	436	caifd->xoff_skb->destructor = caifd->xoff_skb_dtor;
	437
	438	caifd->xoff = 0;
	439	caifd->xoff_skb_dtor = NULL;
	440	caifd->xoff_skb = NULL;
	441
	442	spin_unlock_bh(&caifd->flow_lock);
bd30ce4b	443	caifd_put(caifd);
c72dfae2 SB	444	break;
	445
	446	case NETDEV_UNREGISTER:
bd30ce4b	447	mutex_lock(&caifdevs->lock);
bd30ce4b	448
c72dfae2	449	caifd = caif_get(dev);
bd30ce4b	450	if (caifd == NULL) {
bd30ce4b	451	mutex_unlock(&caifdevs->lock);
f2527ec4	452	break;
bd30ce4b	453	}
	454	list_del_rcu(&caifd->list);
	455
	456	/*
	457	* NETDEV_UNREGISTER is called repeatedly until all reference
	458	* counts for the net-device are released. If references to
	459	* caifd is taken, simply ignore NETDEV_UNREGISTER and wait for
	460	* the next call to NETDEV_UNREGISTER.
	461	*
	462	* If any packets are in flight down the CAIF Stack,
	463	* cfcnfg_del_phy_layer will return nonzero.
	464	* If no packets are in flight, the CAIF Stack associated
	465	* with the net-device un-registering is freed.
	466	*/
	467
	468	if (caifd_refcnt_read(caifd) != 0 \|\|
	469	cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0) {
	470
	471	pr_info("Wait for device inuse\n");
	472	/* Enrole device if CAIF Stack is still in use */
	473	list_add_rcu(&caifd->list, &caifdevs->list);
	474	mutex_unlock(&caifdevs->lock);
	475	break;
	476	}
	477
	478	synchronize_rcu();
	479	dev_put(caifd->netdev);
	480	free_percpu(caifd->pcpu_refcnt);
	481	kfree(caifd);
	482
	483	mutex_unlock(&caifdevs->lock);
c72dfae2 SB	484	break;
	485	}
	486	return 0;
	487	}
	488
	489	static struct notifier_block caif_device_notifier = {
	490	.notifier_call = caif_device_notify,
	491	.priority = 0,
	492	};
	493
c72dfae2 SB	494	/* Per-namespace Caif devices handling */
	495	static int caif_init_net(struct net *net)
	496	{
	497	struct caif_net *caifn = net_generic(net, caif_net_id);
	498	INIT_LIST_HEAD(&caifn->caifdevs.list);
bd30ce4b	499	mutex_init(&caifn->caifdevs.lock);
bee925db	500
bee925db	501	caifn->cfg = cfcnfg_create();
f84ea779	502	if (!caifn->cfg)
bee925db	503	return -ENOMEM;
bee925db	504
c72dfae2 SB	505	return 0;
	506	}
	507
	508	static void caif_exit_net(struct net *net)
	509	{
bd30ce4b	510	struct caif_device_entry caifd, tmp;
	511	struct caif_device_entry_list *caifdevs =
	512	caif_device_list(net);
7c18d220	513	struct cfcnfg *cfg = get_cfcnfg(net);
7c18d220	514
c72dfae2	515	rtnl_lock();
bd30ce4b	516	mutex_lock(&caifdevs->lock);
	517
	518	list_for_each_entry_safe(caifd, tmp, &caifdevs->list, list) {
	519	int i = 0;
	520	list_del_rcu(&caifd->list);
	521	cfcnfg_set_phy_state(cfg, &caifd->layer, false);
	522
	523	while (i < 10 &&
	524	(caifd_refcnt_read(caifd) != 0 \|\|
	525	cfcnfg_del_phy_layer(cfg, &caifd->layer) != 0)) {
	526
	527	pr_info("Wait for device inuse\n");
	528	msleep(250);
	529	i++;
	530	}
	531	synchronize_rcu();
	532	dev_put(caifd->netdev);
	533	free_percpu(caifd->pcpu_refcnt);
	534	kfree(caifd);
c72dfae2	535	}
bee925db	536	cfcnfg_remove(cfg);
bd30ce4b	537
bd30ce4b	538	mutex_unlock(&caifdevs->lock);
c72dfae2 SB	539	rtnl_unlock();
	540	}
	541
	542	static struct pernet_operations caif_net_ops = {
	543	.init = caif_init_net,
	544	.exit = caif_exit_net,
	545	.id = &caif_net_id,
	546	.size = sizeof(struct caif_net),
	547	};
	548
	549	/* Initialize Caif devices list */
	550	static int __init caif_device_init(void)
	551	{
	552	int result;
bd30ce4b	553
8a8ee9af	554	result = register_pernet_subsys(&caif_net_ops);
c72dfae2	555
bee925db	556	if (result)
c72dfae2	557	return result;
bee925db	558
c72dfae2	559	register_netdevice_notifier(&caif_device_notifier);
bee925db	560	dev_add_pack(&caif_packet_type);
c72dfae2 SB	561
c72dfae2 SB	562	return result;
c72dfae2 SB	563	}
	564
	565	static void __exit caif_device_exit(void)
	566	{
c72dfae2	567	unregister_netdevice_notifier(&caif_device_notifier);
bee925db	568	dev_remove_pack(&caif_packet_type);
96f80d12	569	unregister_pernet_subsys(&caif_net_ops);
c72dfae2 SB	570	}
	571
	572	module_init(caif_device_init);
	573	module_exit(caif_device_exit);