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Date:	Thu, 28 Jun 2007 21:20:32 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	kaber@...sh.net
Cc:	peter.p.waskiewicz.jr@...el.com, netdev@...r.kernel.org,
	jeff@...zik.org, auke-jan.h.kok@...el.com, hadi@...erus.ca
Subject: Re: [PATCH 3/3] NET: [SCHED] Qdisc changes and sch_rr added for
 multiqueue

From: Patrick McHardy <kaber@...sh.net>
Date: Thu, 28 Jun 2007 21:24:37 +0200

> Waskiewicz Jr, Peter P wrote:
> >>[...]
> >>The only reasonable thing it can do is not care about 
> >>multiqueue and just dequeue as usual. In fact I think it 
> >>should be an error to configure multiqueue on a non-root qdisc.
> > 
> > 
> > Ack.  This is a thought process that trips me up from time to time...I
> > see child qdisc, and think that's the last qdisc to dequeue and send to
> > the device, not the first one to dequeue.  So please disregard my
> > comments before; I totally agree with you.  Great catch here; I really
> > like the prio_classify() cleanup.
> 
> 
> Thanks. This updated patch makes configuring a non-root qdisc for
> multiqueue an error.

Ok everything is checked into net-2.6.23, thanks everyone.

Now I get to pose a problem for everyone, prove to me how useful
this new code is by showing me how it can be used to solve a
reocurring problem in virtualized network drivers of which I've
had to code one up recently, see my most recent blog entry at:

	http://vger.kernel.org/~davem/cgi-bin/blog.cgi/index.html

Anyways the gist of the issue is (and this happens for Sun LDOMS
networking, lguest, IBM iSeries, etc.) that we have a single
virtualized network device.  There is a "port" to the control
node (which switches packets to the real network for the guest)
and one "port" to each of the other guests.

Each guest gets a unique MAC address.  There is a queue per-port
that can fill up.

What all the drivers like this do right now is stop the queue if
any of the per-port queues fill up, and that's why my sunvnet
driver does right now as well.  We can only thus wakeup the
queue when all of the ports have some space.

The ports (and thus the queues) are selected by destination
MAC address.  Each port has a remote MAC address, if there
is an exact match with a port's remote MAC we'd use that port
and thus that port's queue.  If there is no exact match
(some other node on the real network, broadcast, multicast,
etc.) we want to use the control node's port and port queue.

So the problem to solve is to make a way for drivers to do the queue
selection before the generic queueing layer starts to try and push
things to the driver.  Perhaps a classifier in the driver or similar.

The solution to this problem generalizes to the other facility
we want now, hashing the transmit queue by smp_processor_id()
or similar.  With that in place we can look at doing the TX locking
per-queue too as is hinted at by the comments above the per-queue
structure in the current net-2.6.23 tree.

My current work-in-progress sunvnet.c driver is included below so
we can discuss things concretely with code.

I'm listening. :-)

-------------------- sunvnet.h --------------------
#ifndef _SUNVNET_H
#define _SUNVNET_H

#define DESC_NCOOKIES(entry_size)	\
	((entry_size) - sizeof(struct vio_net_desc))

/* length of time before we decide the hardware is borked,
 * and dev->tx_timeout() should be called to fix the problem
 */
#define VNET_TX_TIMEOUT			(5 * HZ)

#define VNET_TX_RING_SIZE		512
#define VNET_TX_WAKEUP_THRESH(dr)	((dr)->pending / 4)

/* VNET packets are sent in buffers with the first 6 bytes skipped
 * so that after the ethernet header the IPv4/IPv6 headers are aligned
 * properly.
 */
#define VNET_PACKET_SKIP		6

struct vnet_tx_entry {
	void			*buf;
	unsigned int		ncookies;
	struct ldc_trans_cookie	cookies[2];
};

struct vnet;
struct vnet_port {
	struct vio_driver_state	vio;

	struct hlist_node	hash;
	u8			raddr[ETH_ALEN];

	struct vnet		*vp;

	struct vnet_tx_entry	tx_bufs[VNET_TX_RING_SIZE];

	struct list_head	list;
};

static inline struct vnet_port *to_vnet_port(struct vio_driver_state *vio)
{
	return container_of(vio, struct vnet_port, vio);
}

#define VNET_PORT_HASH_SIZE	16
#define VNET_PORT_HASH_MASK	(VNET_PORT_HASH_SIZE - 1)

static inline unsigned int vnet_hashfn(u8 *mac)
{
	unsigned int val = mac[4] ^ mac[5];

	return val & (VNET_PORT_HASH_MASK);
}

struct vnet {
	/* Protects port_list and port_hash.  */
	spinlock_t		lock;

	struct net_device	*dev;

	u32			msg_enable;
	struct vio_dev		*vdev;

	struct list_head	port_list;

	struct hlist_head	port_hash[VNET_PORT_HASH_SIZE];
};

#endif /* _SUNVNET_H */
-------------------- sunvnet.c --------------------
/* sunvnet.c: Sun LDOM Virtual Network Driver.
 *
 * Copyright (C) 2007 David S. Miller <davem@...emloft.net>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/ethtool.h>
#include <linux/etherdevice.h>

#include <asm/vio.h>
#include <asm/ldc.h>

#include "sunvnet.h"

#define DRV_MODULE_NAME		"sunvnet"
#define PFX DRV_MODULE_NAME	": "
#define DRV_MODULE_VERSION	"1.0"
#define DRV_MODULE_RELDATE	"June 25, 2007"

static char version[] __devinitdata =
	DRV_MODULE_NAME ".c:v" DRV_MODULE_VERSION " (" DRV_MODULE_RELDATE ")\n";
MODULE_AUTHOR("David S. Miller (davem@...emloft.net)");
MODULE_DESCRIPTION("Sun LDOM virtual network driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_MODULE_VERSION);

/* Ordered from largest major to lowest */
static struct vio_version vnet_versions[] = {
	{ .major = 1, .minor = 0 },
};

static inline u32 vnet_tx_dring_avail(struct vio_dring_state *dr)
{
	return vio_dring_avail(dr, VNET_TX_RING_SIZE);
}

static int vnet_handle_unknown(struct vnet_port *port, void *arg)
{
	struct vio_msg_tag *pkt = arg;

	printk(KERN_ERR PFX "Received unknown msg [%02x:%02x:%04x:%08x]\n",
	       pkt->type, pkt->stype, pkt->stype_env, pkt->sid);
	printk(KERN_ERR PFX "Resetting connection.\n");

	ldc_disconnect(port->vio.lp);

	return -ECONNRESET;
}

static int vnet_send_attr(struct vio_driver_state *vio)
{
	struct vnet_port *port = to_vnet_port(vio);
	struct net_device *dev = port->vp->dev;
	struct vio_net_attr_info pkt;
	int i;

	memset(&pkt, 0, sizeof(pkt));
	pkt.tag.type = VIO_TYPE_CTRL;
	pkt.tag.stype = VIO_SUBTYPE_INFO;
	pkt.tag.stype_env = VIO_ATTR_INFO;
	pkt.tag.sid = vio_send_sid(vio);
	pkt.xfer_mode = VIO_DRING_MODE;
	pkt.addr_type = VNET_ADDR_ETHERMAC;
	pkt.ack_freq = 0;
	for (i = 0; i < 6; i++)
		pkt.addr |= (u64)dev->dev_addr[i] << ((5 - i) * 8);
	pkt.mtu = ETH_FRAME_LEN;

	viodbg(HS, "SEND NET ATTR xmode[0x%x] atype[0x%x] addr[%llx] "
	       "ackfreq[%u] mtu[%llu]\n",
	       pkt.xfer_mode, pkt.addr_type,
	       (unsigned long long) pkt.addr,
	       pkt.ack_freq,
	       (unsigned long long) pkt.mtu);

	return vio_ldc_send(vio, &pkt, sizeof(pkt));
}

static int handle_attr_info(struct vio_driver_state *vio,
			    struct vio_net_attr_info *pkt)
{
	viodbg(HS, "GOT NET ATTR INFO xmode[0x%x] atype[0x%x] addr[%llx] "
	       "ackfreq[%u] mtu[%llu]\n",
	       pkt->xfer_mode, pkt->addr_type,
	       (unsigned long long) pkt->addr,
	       pkt->ack_freq,
	       (unsigned long long) pkt->mtu);

	pkt->tag.sid = vio_send_sid(vio);

	if (pkt->xfer_mode != VIO_DRING_MODE ||
	    pkt->addr_type != VNET_ADDR_ETHERMAC ||
	    pkt->mtu != ETH_FRAME_LEN) {
		viodbg(HS, "SEND NET ATTR NACK\n");

		pkt->tag.stype = VIO_SUBTYPE_NACK;

		(void) vio_ldc_send(vio, pkt, sizeof(*pkt));

		return -ECONNRESET;
	} else {
		viodbg(HS, "SEND NET ATTR ACK\n");

		pkt->tag.stype = VIO_SUBTYPE_ACK;

		return vio_ldc_send(vio, pkt, sizeof(*pkt));
	}

}

static int handle_attr_ack(struct vio_driver_state *vio,
			   struct vio_net_attr_info *pkt)
{
	viodbg(HS, "GOT NET ATTR ACK\n");

	return 0;
}

static int handle_attr_nack(struct vio_driver_state *vio,
			    struct vio_net_attr_info *pkt)
{
	viodbg(HS, "GOT NET ATTR NACK\n");

	return -ECONNRESET;
}

static int vnet_handle_attr(struct vio_driver_state *vio, void *arg)
{
	struct vio_net_attr_info *pkt = arg;

	switch (pkt->tag.stype) {
	case VIO_SUBTYPE_INFO:
		return handle_attr_info(vio, pkt);

	case VIO_SUBTYPE_ACK:
		return handle_attr_ack(vio, pkt);

	case VIO_SUBTYPE_NACK:
		return handle_attr_nack(vio, pkt);

	default:
		return -ECONNRESET;
	}
}

static void vnet_handshake_complete(struct vio_driver_state *vio)
{
	struct vio_dring_state *dr;

	dr = &vio->drings[VIO_DRIVER_RX_RING];
	dr->snd_nxt = dr->rcv_nxt = 1;

	dr = &vio->drings[VIO_DRIVER_TX_RING];
	dr->snd_nxt = dr->rcv_nxt = 1;
}

/* The hypervisor interface that implements copying to/from imported
 * memory from another domain requires that copies are done to 8-byte
 * aligned buffers, and that the lengths of such copies are also 8-byte
 * multiples.
 *
 * So we align skb->data to an 8-byte multiple and pad-out the data
 * area so we can round the copy length up to the next multiple of
 * 8 for the copy.
 *
 * The transmitter puts the actual start of the packet 6 bytes into
 * the buffer it sends over, so that the IP headers after the ethernet
 * header are aligned properly.  These 6 bytes are not in the descriptor
 * length, they are simply implied.  This offset is represented using
 * the VNET_PACKET_SKIP macro.
 */
static struct sk_buff *alloc_and_align_skb(struct net_device *dev,
					   unsigned int len)
{
	struct sk_buff *skb = netdev_alloc_skb(dev, len+VNET_PACKET_SKIP+8+8);
	unsigned long addr, off;

	if (unlikely(!skb))
		return NULL;

	addr = (unsigned long) skb->data;
	off = ((addr + 7UL) & ~7UL) - addr;
	if (off)
		skb_reserve(skb, off);

	return skb;
}

static int vnet_rx_one(struct vnet_port *port, unsigned int len,
		       struct ldc_trans_cookie *cookies, int ncookies)
{
	struct net_device *dev = port->vp->dev;
	unsigned int copy_len;
	struct sk_buff *skb;
	int err;

	skb = alloc_and_align_skb(dev, len);
	err = -ENOMEM;
	if (!skb) {
		dev->stats.rx_missed_errors++;
		goto out_dropped;
	}

	copy_len = (len + VNET_PACKET_SKIP + 7U) & ~7U;
	skb_put(skb, copy_len);
	err = ldc_copy(port->vio.lp, LDC_COPY_IN,
		       skb->data, copy_len, 0,
		       cookies, ncookies);
	if (err < 0) {
		dev->stats.rx_frame_errors++;
		goto out_free_skb;
	}

	skb_pull(skb, VNET_PACKET_SKIP);
	skb_trim(skb, len);
	skb->protocol = eth_type_trans(skb, dev);

	dev->stats.rx_packets++;
	dev->stats.rx_bytes += len;

	netif_rx(skb);

	return 0;

out_free_skb:
	kfree_skb(skb);

out_dropped:
	dev->stats.rx_dropped++;
	return err;
}

static int vnet_send_ack(struct vnet_port *port, struct vio_dring_state *dr,
			 u32 start, u32 end, u8 vio_dring_state)
{
	struct vio_dring_data hdr = {
		.tag = {
			.type		= VIO_TYPE_DATA,
			.stype		= VIO_SUBTYPE_ACK,
			.stype_env	= VIO_DRING_DATA,
			.sid		= vio_send_sid(&port->vio),
		},
		.dring_ident		= dr->ident,
		.start_idx		= start,
		.end_idx		= end,
		.state			= vio_dring_state,
	};
	int err, delay;

	hdr.seq = dr->snd_nxt;
	delay = 1;
	do {
		err = vio_ldc_send(&port->vio, &hdr, sizeof(hdr));
		if (err > 0) {
			dr->snd_nxt++;
			break;
		}
		udelay(delay);
		if ((delay <<= 1) > 128)
			delay = 128;
	} while (err == -EAGAIN);

	return err;
}

static u32 next_idx(u32 idx, struct vio_dring_state *dr)
{
	if (++idx == dr->num_entries)
		idx = 0;
	return idx;
}

static u32 prev_idx(u32 idx, struct vio_dring_state *dr)
{
	if (idx == 0)
		idx = dr->num_entries - 1;
	else
		idx--;

	return idx;
}

static struct vio_net_desc *get_rx_desc(struct vnet_port *port,
					struct vio_dring_state *dr,
					u32 index)
{
	struct vio_net_desc *desc = port->vio.desc_buf;
	int err;

	err = ldc_get_dring_entry(port->vio.lp, desc, dr->entry_size,
				  (index * dr->entry_size),
				  dr->cookies, dr->ncookies);
	if (err < 0)
		return ERR_PTR(err);

	return desc;
}

static int put_rx_desc(struct vnet_port *port,
		       struct vio_dring_state *dr,
		       struct vio_net_desc *desc,
		       u32 index)
{
	int err;

	err = ldc_put_dring_entry(port->vio.lp, desc, dr->entry_size,
				  (index * dr->entry_size),
				  dr->cookies, dr->ncookies);
	if (err < 0)
		return err;

	return 0;
}

static int vnet_walk_rx_one(struct vnet_port *port,
			    struct vio_dring_state *dr,
			    u32 index, int *needs_ack)
{
	struct vio_net_desc *desc = get_rx_desc(port, dr, index);
	struct vio_driver_state *vio = &port->vio;
	int err;

	if (IS_ERR(desc))
		return PTR_ERR(desc);

	viodbg(DATA, "vio_walk_rx_one desc[%02x:%02x:%08x:%08x:%lx:%lx]\n",
	       desc->hdr.state, desc->hdr.ack,
	       desc->size, desc->ncookies,
	       desc->cookies[0].cookie_addr,
	       desc->cookies[0].cookie_size);

	if (desc->hdr.state != VIO_DESC_READY)
		return 1;
	err = vnet_rx_one(port, desc->size, desc->cookies, desc->ncookies);
	if (err == -ECONNRESET)
		return err;
	desc->hdr.state = VIO_DESC_DONE;
	err = put_rx_desc(port, dr, desc, index);
	if (err < 0)
		return err;
	*needs_ack = desc->hdr.ack;
	return 0;
}

static int vnet_walk_rx(struct vnet_port *port, struct vio_dring_state *dr,
			u32 start, u32 end)
{
	struct vio_driver_state *vio = &port->vio;
	int ack_start = -1, ack_end = -1;

	end = (end == (u32) -1) ? prev_idx(start, dr) : next_idx(end, dr);

	viodbg(DATA, "vnet_walk_rx start[%08x] end[%08x]\n", start, end);

	while (start != end) {
		int ack = 0, err = vnet_walk_rx_one(port, dr, start, &ack);
		if (err == -ECONNRESET)
			return err;
		if (err != 0)
			break;
		if (ack_start == -1)
			ack_start = start;
		ack_end = start;
		start = next_idx(start, dr);
		if (ack && start != end) {
			err = vnet_send_ack(port, dr, ack_start, ack_end,
					    VIO_DRING_ACTIVE);
			if (err == -ECONNRESET)
				return err;
			ack_start = -1;
		}
	}
	if (unlikely(ack_start == -1))
		ack_start = ack_end = prev_idx(start, dr);
	return vnet_send_ack(port, dr, ack_start, ack_end, VIO_DRING_STOPPED);
}

static int vnet_rx(struct vnet_port *port, void *msgbuf)
{
	struct vio_dring_data *pkt = msgbuf;
	struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_RX_RING];
	struct vio_driver_state *vio = &port->vio;

	viodbg(DATA, "vnet_rx stype_env[%04x] seq[%016lx] rcv_nxt[%016lx]\n",
	       pkt->tag.stype_env, pkt->seq, dr->rcv_nxt);

	if (unlikely(pkt->tag.stype_env != VIO_DRING_DATA))
		return 0;
	if (unlikely(pkt->seq != dr->rcv_nxt)) {
		printk(KERN_ERR PFX "RX out of sequence seq[0x%lx] "
		       "rcv_nxt[0x%lx]\n", pkt->seq, dr->rcv_nxt);
		return 0;
	}

	dr->rcv_nxt++;

	/* XXX Validate pkt->start_idx and pkt->end_idx XXX */

	return vnet_walk_rx(port, dr, pkt->start_idx, pkt->end_idx);
}

static int idx_is_pending(struct vio_dring_state *dr, u32 end)
{
	u32 idx = dr->cons;
	int found = 0;

	while (idx != dr->prod) {
		if (idx == end) {
			found = 1;
			break;
		}
		idx = next_idx(idx, dr);
	}
	return found;
}

static int vnet_ack(struct vnet_port *port, void *msgbuf)
{
	struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
	struct vio_dring_data *pkt = msgbuf;
	struct net_device *dev;
	struct vnet *vp;
	u32 end;

	if (unlikely(pkt->tag.stype_env != VIO_DRING_DATA))
		return 0;

	end = pkt->end_idx;
	if (unlikely(!idx_is_pending(dr, end)))
		return 0;

	dr->cons = next_idx(end, dr);

	vp = port->vp;
	dev = vp->dev;
	if (unlikely(netif_queue_stopped(dev) &&
		     vnet_tx_dring_avail(dr) >= VNET_TX_WAKEUP_THRESH(dr)))
		return 1;

	return 0;
}

static int vnet_nack(struct vnet_port *port, void *msgbuf)
{
	/* XXX just reset or similar XXX */
	return 0;
}

static void maybe_tx_wakeup(struct vnet *vp)
{
	struct net_device *dev = vp->dev;

	netif_tx_lock(dev);
	if (likely(netif_queue_stopped(dev))) {
		struct vnet_port *port;
		int wake = 1;

		list_for_each_entry(port, &vp->port_list, list) {
			struct vio_dring_state *dr;

			dr = &port->vio.drings[VIO_DRIVER_TX_RING];
			if (vnet_tx_dring_avail(dr) <
			    VNET_TX_WAKEUP_THRESH(dr)) {
				wake = 0;
				break;
			}
		}
		if (wake)
			netif_wake_queue(dev);
	}
	netif_tx_unlock(dev);
}

static void vnet_event(void *arg, int event)
{
	struct vnet_port *port = arg;
	struct vio_driver_state *vio = &port->vio;
	unsigned long flags;
	int tx_wakeup, err;

	spin_lock_irqsave(&vio->lock, flags);

	if (unlikely(event == LDC_EVENT_RESET ||
		     event == LDC_EVENT_UP)) {
		vio_link_state_change(vio, event);
		spin_unlock_irqrestore(&vio->lock, flags);

		return;
	}

	if (unlikely(event != LDC_EVENT_DATA_READY)) {
		printk(KERN_WARNING PFX "Unexpected LDC event %d\n", event);
		spin_unlock_irqrestore(&vio->lock, flags);
		return;
	}

	tx_wakeup = err = 0;
	while (1) {
		union {
			struct vio_msg_tag tag;
			u64 raw[8];
		} msgbuf;

		err = ldc_read(vio->lp, &msgbuf, sizeof(msgbuf));
		if (unlikely(err < 0)) {
			if (err == -ECONNRESET)
				vio_conn_reset(vio);
			break;
		}
		if (err == 0)
			break;
		viodbg(DATA, "TAG [%02x:%02x:%04x:%08x]\n",
		       msgbuf.tag.type,
		       msgbuf.tag.stype,
		       msgbuf.tag.stype_env,
		       msgbuf.tag.sid);
		err = vio_validate_sid(vio, &msgbuf.tag);
		if (err < 0)
			break;

		if (likely(msgbuf.tag.type == VIO_TYPE_DATA)) {
			if (msgbuf.tag.stype == VIO_SUBTYPE_INFO) {
				err = vnet_rx(port, &msgbuf);
			} else if (msgbuf.tag.stype == VIO_SUBTYPE_ACK) {
				err = vnet_ack(port, &msgbuf);
				if (err > 0)
					tx_wakeup |= err;
			} else if (msgbuf.tag.stype == VIO_SUBTYPE_NACK) {
				err = vnet_nack(port, &msgbuf);
			}
		} else if (msgbuf.tag.type == VIO_TYPE_CTRL) {
			err = vio_control_pkt_engine(vio, &msgbuf);
			if (err)
				break;
		} else {
			err = vnet_handle_unknown(port, &msgbuf);
		}
		if (err == -ECONNRESET)
			break;
	}
	spin_unlock(&vio->lock);
	if (unlikely(tx_wakeup && err != -ECONNRESET))
		maybe_tx_wakeup(port->vp);
	local_irq_restore(flags);
}

static int __vnet_tx_trigger(struct vnet_port *port)
{
	struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
	struct vio_dring_data hdr = {
		.tag = {
			.type		= VIO_TYPE_DATA,
			.stype		= VIO_SUBTYPE_INFO,
			.stype_env	= VIO_DRING_DATA,
			.sid		= vio_send_sid(&port->vio),
		},
		.dring_ident		= dr->ident,
		.start_idx		= dr->prod,
		.end_idx		= (u32) -1,
	};
	int err, delay;

	hdr.seq = dr->snd_nxt;
	delay = 1;
	do {
		err = vio_ldc_send(&port->vio, &hdr, sizeof(hdr));
		if (err > 0) {
			dr->snd_nxt++;
			break;
		}
		udelay(delay);
		if ((delay <<= 1) > 128)
			delay = 128;
	} while (err == -EAGAIN);

	return err;
}

struct vnet_port *__tx_port_find(struct vnet *vp, struct sk_buff *skb)
{
	unsigned int hash = vnet_hashfn(skb->data);
	struct hlist_head *hp = &vp->port_hash[hash];
	struct hlist_node *n;
	struct vnet_port *port;

	hlist_for_each_entry(port, n, hp, hash) {
		if (!compare_ether_addr(port->raddr, skb->data))
			return port;
	}
	port = NULL;
	if (!list_empty(&vp->port_list))
		port = list_entry(vp->port_list.next, struct vnet_port, list);

	return port;
}

struct vnet_port *tx_port_find(struct vnet *vp, struct sk_buff *skb)
{
	struct vnet_port *ret;
	unsigned long flags;

	spin_lock_irqsave(&vp->lock, flags);
	ret = __tx_port_find(vp, skb);
	spin_unlock_irqrestore(&vp->lock, flags);

	return ret;
}

static int vnet_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct vnet *vp = netdev_priv(dev);
	struct vnet_port *port = tx_port_find(vp, skb);
	struct vio_dring_state *dr;
	struct vio_net_desc *d;
	unsigned long flags;
	unsigned int len;
	void *tx_buf;
	int i, err;

	if (unlikely(!port))
		goto out_dropped;

	spin_lock_irqsave(&port->vio.lock, flags);

	dr = &port->vio.drings[VIO_DRIVER_TX_RING];
	if (unlikely(vnet_tx_dring_avail(dr) < 2)) {
		if (!netif_queue_stopped(dev)) {
			netif_stop_queue(dev);

			/* This is a hard error, log it. */
			printk(KERN_ERR PFX "%s: BUG! Tx Ring full when "
			       "queue awake!\n", dev->name);
			dev->stats.tx_errors++;
		}
		spin_unlock_irqrestore(&port->vio.lock, flags);
		return NETDEV_TX_BUSY;
	}

	d = vio_dring_cur(dr);

	tx_buf = port->tx_bufs[dr->prod].buf;
	skb_copy_from_linear_data(skb, tx_buf + VNET_PACKET_SKIP, skb->len);

	len = skb->len;
	if (len < ETH_ZLEN) {
		len = ETH_ZLEN;
		memset(tx_buf+VNET_PACKET_SKIP+skb->len, 0, len - skb->len);
	}

	d->hdr.ack = VIO_ACK_ENABLE;
	d->size = len;
	d->ncookies = port->tx_bufs[dr->prod].ncookies;
	for (i = 0; i < d->ncookies; i++)
		d->cookies[i] = port->tx_bufs[dr->prod].cookies[i];

	/* This has to be a non-SMP write barrier because we are writing
	 * to memory which is shared with the peer LDOM.
	 */
	wmb();

	d->hdr.state = VIO_DESC_READY;

	err = __vnet_tx_trigger(port);
	if (unlikely(err < 0)) {
		printk(KERN_INFO PFX "%s: TX trigger error %d\n",
		       dev->name, err);
		d->hdr.state = VIO_DESC_FREE;
		dev->stats.tx_carrier_errors++;
		goto out_dropped_unlock;
	}

	dev->stats.tx_packets++;
	dev->stats.tx_bytes += skb->len;

	dr->prod = (dr->prod + 1) & (VNET_TX_RING_SIZE - 1);
	if (unlikely(vnet_tx_dring_avail(dr) < 2)) {
		netif_stop_queue(dev);
		if (vnet_tx_dring_avail(dr) > VNET_TX_WAKEUP_THRESH(dr))
			netif_wake_queue(dev);
	}

	spin_unlock_irqrestore(&port->vio.lock, flags);

	dev_kfree_skb(skb);

	dev->trans_start = jiffies;
	return NETDEV_TX_OK;

out_dropped_unlock:
	spin_unlock_irqrestore(&port->vio.lock, flags);

out_dropped:
	dev_kfree_skb(skb);
	dev->stats.tx_dropped++;
	return NETDEV_TX_OK;
}

static void vnet_tx_timeout(struct net_device *dev)
{
	/* XXX Implement me XXX */
}

static int vnet_open(struct net_device *dev)
{
	netif_carrier_on(dev);
	netif_start_queue(dev);

	return 0;
}

static int vnet_close(struct net_device *dev)
{
	netif_stop_queue(dev);
	netif_carrier_off(dev);

	return 0;
}

static void vnet_set_rx_mode(struct net_device *dev)
{
	/* XXX Implement multicast support XXX */
}

static int vnet_change_mtu(struct net_device *dev, int new_mtu)
{
	if (new_mtu != ETH_DATA_LEN)
		return -EINVAL;

	dev->mtu = new_mtu;
	return 0;
}

static int vnet_set_mac_addr(struct net_device *dev, void *p)
{
	return -EINVAL;
}

static void vnet_get_drvinfo(struct net_device *dev,
			     struct ethtool_drvinfo *info)
{
	strcpy(info->driver, DRV_MODULE_NAME);
	strcpy(info->version, DRV_MODULE_VERSION);
}

static u32 vnet_get_msglevel(struct net_device *dev)
{
	struct vnet *vp = netdev_priv(dev);
	return vp->msg_enable;
}

static void vnet_set_msglevel(struct net_device *dev, u32 value)
{
	struct vnet *vp = netdev_priv(dev);
	vp->msg_enable = value;
}

static const struct ethtool_ops vnet_ethtool_ops = {
	.get_drvinfo		= vnet_get_drvinfo,
	.get_msglevel		= vnet_get_msglevel,
	.set_msglevel		= vnet_set_msglevel,
	.get_link		= ethtool_op_get_link,
	.get_perm_addr		= ethtool_op_get_perm_addr,
};

static void vnet_port_free_tx_bufs(struct vnet_port *port)
{
	struct vio_dring_state *dr;
	int i;

	dr = &port->vio.drings[VIO_DRIVER_TX_RING];
	if (dr->base) {
		ldc_free_exp_dring(port->vio.lp, dr->base,
				   (dr->entry_size * dr->num_entries),
				   dr->cookies, dr->ncookies);
		dr->base = NULL;
		dr->entry_size = 0;
		dr->num_entries = 0;
		dr->pending = 0;
		dr->ncookies = 0;
	}

	for (i = 0; i < VNET_TX_RING_SIZE; i++) {
		void *buf = port->tx_bufs[i].buf;

		if (!buf)
			continue;

		ldc_unmap(port->vio.lp,
			  port->tx_bufs[i].cookies,
			  port->tx_bufs[i].ncookies);

		kfree(buf);
		port->tx_bufs[i].buf = NULL;
	}
}

static int __devinit vnet_port_alloc_tx_bufs(struct vnet_port *port)
{
	struct vio_dring_state *dr;
	unsigned long len;
	int i, err, ncookies;
	void *dring;

	for (i = 0; i < VNET_TX_RING_SIZE; i++) {
		void *buf = kzalloc(ETH_FRAME_LEN + 8, GFP_KERNEL);
		int map_len = (ETH_FRAME_LEN + 7) & ~7;

		err = -ENOMEM;
		if (!buf) {
			printk(KERN_ERR "TX buffer allocation failure\n");
			goto err_out;
		}
		err = -EFAULT;
		if ((unsigned long)buf & (8UL - 1)) {
			printk(KERN_ERR "TX buffer misaligned\n");
			kfree(buf);
			goto err_out;
		}

		err = ldc_map_single(port->vio.lp, buf, map_len,
				     port->tx_bufs[i].cookies, 2,
				     (LDC_MAP_SHADOW |
				      LDC_MAP_DIRECT |
				      LDC_MAP_RW));
		if (err < 0) {
			kfree(buf);
			goto err_out;
		}
		port->tx_bufs[i].buf = buf;
		port->tx_bufs[i].ncookies = err;
	}

	dr = &port->vio.drings[VIO_DRIVER_TX_RING];

	len = (VNET_TX_RING_SIZE *
	       (sizeof(struct vio_net_desc) +
		(sizeof(struct ldc_trans_cookie) * 2)));

	ncookies = VIO_MAX_RING_COOKIES;
	dring = ldc_alloc_exp_dring(port->vio.lp, len,
				    dr->cookies, &ncookies,
				    (LDC_MAP_SHADOW |
				     LDC_MAP_DIRECT |
				     LDC_MAP_RW));
	if (IS_ERR(dring)) {
		err = PTR_ERR(dring);
		goto err_out;
	}

	dr->base = dring;
	dr->entry_size = (sizeof(struct vio_net_desc) +
			  (sizeof(struct ldc_trans_cookie) * 2));
	dr->num_entries = VNET_TX_RING_SIZE;
	dr->prod = dr->cons = 0;
	dr->pending = VNET_TX_RING_SIZE;
	dr->ncookies = ncookies;

	return 0;

err_out:
	vnet_port_free_tx_bufs(port);

	return err;
}

static struct ldc_channel_config vnet_ldc_cfg = {
	.event		= vnet_event,
	.mtu		= 64,
	.mode		= LDC_MODE_UNRELIABLE,
};

static struct vio_driver_ops vnet_vio_ops = {
	.send_attr		= vnet_send_attr,
	.handle_attr		= vnet_handle_attr,
	.handshake_complete	= vnet_handshake_complete,
};

const char *remote_macaddr_prop = "remote-mac-address";

static int __devinit vnet_port_probe(struct vio_dev *vdev,
				     const struct vio_device_id *id)
{
	struct mdesc_node *endp;
	struct vnet_port *port;
	unsigned long flags;
	struct vnet *vp;
	const u64 *rmac;
	int len, i, err, switch_port;

	vp = dev_get_drvdata(vdev->dev.parent);
	if (!vp) {
		printk(KERN_ERR PFX "Cannot find port parent vnet.\n");
		return -ENODEV;
	}

	rmac = md_get_property(vdev->mp, remote_macaddr_prop, &len);
	if (!rmac) {
		printk(KERN_ERR PFX "Port lacks %s property.\n",
		       remote_macaddr_prop);
		return -ENODEV;
	}

	endp = vio_find_endpoint(vdev);
	if (!endp) {
		printk(KERN_ERR PFX "Port lacks channel-endpoint.\n");
		return -ENODEV;
	}

	port = kzalloc(sizeof(*port), GFP_KERNEL);
	if (!port) {
		printk(KERN_ERR PFX "Cannot allocate vnet_port.\n");
		return -ENOMEM;
	}

	for (i = 0; i < ETH_ALEN; i++)
		port->raddr[i] = (*rmac >> (5 - i) * 8) & 0xff;

	port->vp = vp;

	err = vio_driver_init(&port->vio, vdev, VDEV_NETWORK, endp,
			      vnet_versions, ARRAY_SIZE(vnet_versions),
			      &vnet_vio_ops, vp->dev->name);
	if (err)
		goto err_out_free_port;

	err = vio_ldc_alloc(&port->vio, &vnet_ldc_cfg, port);
	if (err)
		goto err_out_free_port;

	err = vnet_port_alloc_tx_bufs(port);
	if (err)
		goto err_out_free_ldc;

	INIT_HLIST_NODE(&port->hash);
	INIT_LIST_HEAD(&port->list);

	switch_port = 0;
	if (md_get_property(vdev->mp, "switch-port", NULL) != NULL)
		switch_port = 1;

	spin_lock_irqsave(&vp->lock, flags);
	if (switch_port)
		list_add(&port->list, &vp->port_list);
	else
		list_add_tail(&port->list, &vp->port_list);
	hlist_add_head(&port->hash, &vp->port_hash[vnet_hashfn(port->raddr)]);
	spin_unlock_irqrestore(&vp->lock, flags);

	dev_set_drvdata(&vdev->dev, port);

	printk(KERN_INFO "%s: PORT ( remote-mac ", vp->dev->name);
	for (i = 0; i < 6; i++)
		printk("%2.2x%c", port->raddr[i], i == 5 ? ' ' : ':');
	if (switch_port)
		printk("switch-port ");
	printk(")\n");

	vio_port_up(&port->vio);

	return 0;

err_out_free_ldc:
	vio_ldc_free(&port->vio);

err_out_free_port:
	kfree(port);

	return err;
}

static int vnet_port_remove(struct vio_dev *vdev)
{
	struct vnet_port *port = dev_get_drvdata(&vdev->dev);

	if (port) {
		struct vnet *vp = port->vp;
		unsigned long flags;

		del_timer_sync(&port->vio.timer);

		spin_lock_irqsave(&vp->lock, flags);
		list_del(&port->list);
		hlist_del(&port->hash);
		spin_unlock_irqrestore(&vp->lock, flags);

		vnet_port_free_tx_bufs(port);
		vio_ldc_free(&port->vio);

		dev_set_drvdata(&vdev->dev, NULL);

		kfree(port);
	}
	return 0;
}

static struct vio_device_id vnet_port_match[] = {
	{
		.type = "vnet-port",
	},
	{},
};
MODULE_DEVICE_TABLE(vio, vnet_match);

static struct vio_driver vnet_port_driver = {
	.id_table	= vnet_port_match,
	.probe		= vnet_port_probe,
	.remove		= vnet_port_remove,
	.driver		= {
		.name	= "vnet_port",
		.owner	= THIS_MODULE,
	}
};

const char *local_mac_prop = "local-mac-address";

static int __devinit vnet_probe(struct vio_dev *vdev,
				const struct vio_device_id *id)
{
	static int vnet_version_printed;
	struct net_device *dev;
	struct vnet *vp;
	const u64 *mac;
	int err, i, len;

	if (vnet_version_printed++ == 0)
		printk(KERN_INFO "%s", version);

	mac = md_get_property(vdev->mp, local_mac_prop, &len);
	if (!mac) {
		printk(KERN_ERR PFX "vnet lacks %s property.\n",
		       local_mac_prop);
		err = -ENODEV;
		goto err_out;
	}

	dev = alloc_etherdev(sizeof(*vp));
	if (!dev) {
		printk(KERN_ERR PFX "Etherdev alloc failed, aborting.\n");
		err = -ENOMEM;
		goto err_out;
	}

	for (i = 0; i < ETH_ALEN; i++)
		dev->dev_addr[i] = (*mac >> (5 - i) * 8) & 0xff;

	memcpy(dev->perm_addr, dev->dev_addr, dev->addr_len);

	SET_NETDEV_DEV(dev, &vdev->dev);

	vp = netdev_priv(dev);

	spin_lock_init(&vp->lock);
	vp->dev = dev;
	vp->vdev = vdev;

	INIT_LIST_HEAD(&vp->port_list);
	for (i = 0; i < VNET_PORT_HASH_SIZE; i++)
		INIT_HLIST_HEAD(&vp->port_hash[i]);

	dev->open = vnet_open;
	dev->stop = vnet_close;
	dev->set_multicast_list = vnet_set_rx_mode;
	dev->set_mac_address = vnet_set_mac_addr;
	dev->tx_timeout = vnet_tx_timeout;
	dev->ethtool_ops = &vnet_ethtool_ops;
	dev->watchdog_timeo = VNET_TX_TIMEOUT;
	dev->change_mtu = vnet_change_mtu;
	dev->hard_start_xmit = vnet_start_xmit;

	err = register_netdev(dev);
	if (err) {
		printk(KERN_ERR PFX "Cannot register net device, "
		       "aborting.\n");
		goto err_out_free_dev;
	}

	printk(KERN_INFO "%s: Sun LDOM vnet ", dev->name);

	for (i = 0; i < 6; i++)
		printk("%2.2x%c", dev->dev_addr[i], i == 5 ? '\n' : ':');

	dev_set_drvdata(&vdev->dev, vp);

	return 0;

err_out_free_dev:
	free_netdev(dev);

err_out:
	return err;
}

static int vnet_remove(struct vio_dev *vdev)
{

	struct vnet *vp = dev_get_drvdata(&vdev->dev);

	if (vp) {
		/* XXX unregister port, or at least check XXX */
		unregister_netdevice(vp->dev);
		dev_set_drvdata(&vdev->dev, NULL);
	}
	return 0;
}

static struct vio_device_id vnet_match[] = {
	{
		.type = "network",
	},
	{},
};
MODULE_DEVICE_TABLE(vio, vnet_match);

static struct vio_driver vnet_driver = {
	.id_table	= vnet_match,
	.probe		= vnet_probe,
	.remove		= vnet_remove,
	.driver		= {
		.name	= "vnet",
		.owner	= THIS_MODULE,
	}
};

static int __init vnet_init(void)
{
	int err = vio_register_driver(&vnet_driver);

	if (!err) {
		err = vio_register_driver(&vnet_port_driver);
		if (err)
			vio_unregister_driver(&vnet_driver);
	}

	return err;
}

static void __exit vnet_exit(void)
{
	vio_unregister_driver(&vnet_port_driver);
	vio_unregister_driver(&vnet_driver);
}

module_init(vnet_init);
module_exit(vnet_exit);
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