[linux-2.6-block.git] / drivers / net / xen-netback / rx.c

/*
 * Copyright (c) 2016 Citrix Systems Inc.
 * Copyright (c) 2002-2005, K A Fraser
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */
#include "common.h"

#include <linux/kthread.h>

#include <xen/xen.h>
#include <xen/events.h>

/*
 * Update the needed ring page slots for the first SKB queued.
 * Note that any call sequence outside the RX thread calling this function
 * needs to wake up the RX thread via a call of xenvif_kick_thread()
 * afterwards in order to avoid a race with putting the thread to sleep.
 */
static void xenvif_update_needed_slots(struct xenvif_queue *queue,
				       const struct sk_buff *skb)
{
	unsigned int needed = 0;

	if (skb) {
		needed = DIV_ROUND_UP(skb->len, XEN_PAGE_SIZE);
		if (skb_is_gso(skb))
			needed++;
		if (skb->sw_hash)
			needed++;
	}

	WRITE_ONCE(queue->rx_slots_needed, needed);
}

static bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue)
{
	RING_IDX prod, cons;
	unsigned int needed;

	needed = READ_ONCE(queue->rx_slots_needed);
	if (!needed)
		return false;

	do {
		prod = queue->rx.sring->req_prod;
		cons = queue->rx.req_cons;

		if (prod - cons >= needed)
			return true;

		queue->rx.sring->req_event = prod + 1;

		/* Make sure event is visible before we check prod
		 * again.
		 */
		mb();
	} while (queue->rx.sring->req_prod != prod);

	return false;
}

void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb)
{
	unsigned long flags;

	spin_lock_irqsave(&queue->rx_queue.lock, flags);

	if (queue->rx_queue_len >= queue->rx_queue_max) {
		struct net_device *dev = queue->vif->dev;

		netif_tx_stop_queue(netdev_get_tx_queue(dev, queue->id));
		kfree_skb(skb);
		queue->vif->dev->stats.rx_dropped++;
	} else {
		if (skb_queue_empty(&queue->rx_queue))
			xenvif_update_needed_slots(queue, skb);

		__skb_queue_tail(&queue->rx_queue, skb);

		queue->rx_queue_len += skb->len;
	}

	spin_unlock_irqrestore(&queue->rx_queue.lock, flags);
}

static struct sk_buff *xenvif_rx_dequeue(struct xenvif_queue *queue)
{
	struct sk_buff *skb;

	spin_lock_irq(&queue->rx_queue.lock);

	skb = __skb_dequeue(&queue->rx_queue);
	if (skb) {
		xenvif_update_needed_slots(queue, skb_peek(&queue->rx_queue));

		queue->rx_queue_len -= skb->len;
		if (queue->rx_queue_len < queue->rx_queue_max) {
			struct netdev_queue *txq;

			txq = netdev_get_tx_queue(queue->vif->dev, queue->id);
			netif_tx_wake_queue(txq);
		}
	}

	spin_unlock_irq(&queue->rx_queue.lock);

	return skb;
}

static void xenvif_rx_queue_purge(struct xenvif_queue *queue)
{
	struct sk_buff *skb;

	while ((skb = xenvif_rx_dequeue(queue)) != NULL)
		kfree_skb(skb);
}

static void xenvif_rx_queue_drop_expired(struct xenvif_queue *queue)
{
	struct sk_buff *skb;

	for (;;) {
		skb = skb_peek(&queue->rx_queue);
		if (!skb)
			break;
		if (time_before(jiffies, XENVIF_RX_CB(skb)->expires))
			break;
		xenvif_rx_dequeue(queue);
		kfree_skb(skb);
		queue->vif->dev->stats.rx_dropped++;
	}
}

static void xenvif_rx_copy_flush(struct xenvif_queue *queue)
{
	unsigned int i;
	int notify;

	gnttab_batch_copy(queue->rx_copy.op, queue->rx_copy.num);

	for (i = 0; i < queue->rx_copy.num; i++) {
		struct gnttab_copy *op;

		op = &queue->rx_copy.op[i];

		/* If the copy failed, overwrite the status field in
		 * the corresponding response.
		 */
		if (unlikely(op->status != GNTST_okay)) {
			struct xen_netif_rx_response *rsp;

			rsp = RING_GET_RESPONSE(&queue->rx,
						queue->rx_copy.idx[i]);
			rsp->status = op->status;
		}
	}

	queue->rx_copy.num = 0;

	/* Push responses for all completed packets. */
	RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->rx, notify);
	if (notify)
		notify_remote_via_irq(queue->rx_irq);

	__skb_queue_purge(queue->rx_copy.completed);
}

static void xenvif_rx_copy_add(struct xenvif_queue *queue,
			       struct xen_netif_rx_request *req,
			       unsigned int offset, void *data, size_t len)
{
	struct gnttab_copy *op;
	struct page *page;
	struct xen_page_foreign *foreign;

	if (queue->rx_copy.num == COPY_BATCH_SIZE)
		xenvif_rx_copy_flush(queue);

	op = &queue->rx_copy.op[queue->rx_copy.num];

	page = virt_to_page(data);

	op->flags = GNTCOPY_dest_gref;

	foreign = xen_page_foreign(page);
	if (foreign) {
		op->source.domid = foreign->domid;
		op->source.u.ref = foreign->gref;
		op->flags |= GNTCOPY_source_gref;
	} else {
		op->source.u.gmfn = virt_to_gfn(data);
		op->source.domid  = DOMID_SELF;
	}

	op->source.offset = xen_offset_in_page(data);
	op->dest.u.ref    = req->gref;
	op->dest.domid    = queue->vif->domid;
	op->dest.offset   = offset;
	op->len           = len;

	queue->rx_copy.idx[queue->rx_copy.num] = queue->rx.req_cons;
	queue->rx_copy.num++;
}

static unsigned int xenvif_gso_type(struct sk_buff *skb)
{
	if (skb_is_gso(skb)) {
		if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
			return XEN_NETIF_GSO_TYPE_TCPV4;
		else
			return XEN_NETIF_GSO_TYPE_TCPV6;
	}
	return XEN_NETIF_GSO_TYPE_NONE;
}

struct xenvif_pkt_state {
	struct sk_buff *skb;
	size_t remaining_len;
	struct sk_buff *frag_iter;
	int frag; /* frag == -1 => frag_iter->head */
	unsigned int frag_offset;
	struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX - 1];
	unsigned int extra_count;
	unsigned int slot;
};

static void xenvif_rx_next_skb(struct xenvif_queue *queue,
			       struct xenvif_pkt_state *pkt)
{
	struct sk_buff *skb;
	unsigned int gso_type;

	skb = xenvif_rx_dequeue(queue);

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

	/* Reset packet state. */
	memset(pkt, 0, sizeof(struct xenvif_pkt_state));

	pkt->skb = skb;
	pkt->frag_iter = skb;
	pkt->remaining_len = skb->len;
	pkt->frag = -1;

	gso_type = xenvif_gso_type(skb);
	if ((1 << gso_type) & queue->vif->gso_mask) {
		struct xen_netif_extra_info *extra;

		extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];

		extra->u.gso.type = gso_type;
		extra->u.gso.size = skb_shinfo(skb)->gso_size;
		extra->u.gso.pad = 0;
		extra->u.gso.features = 0;
		extra->type = XEN_NETIF_EXTRA_TYPE_GSO;
		extra->flags = 0;

		pkt->extra_count++;
	}

	if (queue->vif->xdp_headroom) {
		struct xen_netif_extra_info *extra;

		extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_XDP - 1];

		memset(extra, 0, sizeof(struct xen_netif_extra_info));
		extra->u.xdp.headroom = queue->vif->xdp_headroom;
		extra->type = XEN_NETIF_EXTRA_TYPE_XDP;
		extra->flags = 0;

		pkt->extra_count++;
	}

	if (skb->sw_hash) {
		struct xen_netif_extra_info *extra;

		extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_HASH - 1];

		extra->u.hash.algorithm =
			XEN_NETIF_CTRL_HASH_ALGORITHM_TOEPLITZ;

		if (skb->l4_hash)
			extra->u.hash.type =
				skb->protocol == htons(ETH_P_IP) ?
				_XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP :
				_XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP;
		else
			extra->u.hash.type =
				skb->protocol == htons(ETH_P_IP) ?
				_XEN_NETIF_CTRL_HASH_TYPE_IPV4 :
				_XEN_NETIF_CTRL_HASH_TYPE_IPV6;

		*(uint32_t *)extra->u.hash.value = skb_get_hash_raw(skb);

		extra->type = XEN_NETIF_EXTRA_TYPE_HASH;
		extra->flags = 0;

		pkt->extra_count++;
	}
}

static void xenvif_rx_complete(struct xenvif_queue *queue,
			       struct xenvif_pkt_state *pkt)
{
	/* All responses are ready to be pushed. */
	queue->rx.rsp_prod_pvt = queue->rx.req_cons;

	__skb_queue_tail(queue->rx_copy.completed, pkt->skb);
}

static void xenvif_rx_next_frag(struct xenvif_pkt_state *pkt)
{
	struct sk_buff *frag_iter = pkt->frag_iter;
	unsigned int nr_frags = skb_shinfo(frag_iter)->nr_frags;

	pkt->frag++;
	pkt->frag_offset = 0;

	if (pkt->frag >= nr_frags) {
		if (frag_iter == pkt->skb)
			pkt->frag_iter = skb_shinfo(frag_iter)->frag_list;
		else
			pkt->frag_iter = frag_iter->next;

		pkt->frag = -1;
	}
}

static void xenvif_rx_next_chunk(struct xenvif_queue *queue,
				 struct xenvif_pkt_state *pkt,
				 unsigned int offset, void **data,
				 size_t *len)
{
	struct sk_buff *frag_iter = pkt->frag_iter;
	void *frag_data;
	size_t frag_len, chunk_len;

	BUG_ON(!frag_iter);

	if (pkt->frag == -1) {
		frag_data = frag_iter->data;
		frag_len = skb_headlen(frag_iter);
	} else {
		skb_frag_t *frag = &skb_shinfo(frag_iter)->frags[pkt->frag];

		frag_data = skb_frag_address(frag);
		frag_len = skb_frag_size(frag);
	}

	frag_data += pkt->frag_offset;
	frag_len -= pkt->frag_offset;

	chunk_len = min_t(size_t, frag_len, XEN_PAGE_SIZE - offset);
	chunk_len = min_t(size_t, chunk_len, XEN_PAGE_SIZE -
					     xen_offset_in_page(frag_data));

	pkt->frag_offset += chunk_len;

	/* Advance to next frag? */
	if (frag_len == chunk_len)
		xenvif_rx_next_frag(pkt);

	*data = frag_data;
	*len = chunk_len;
}

static void xenvif_rx_data_slot(struct xenvif_queue *queue,
				struct xenvif_pkt_state *pkt,
				struct xen_netif_rx_request *req,
				struct xen_netif_rx_response *rsp)
{
	unsigned int offset = queue->vif->xdp_headroom;
	unsigned int flags;

	do {
		size_t len;
		void *data;

		xenvif_rx_next_chunk(queue, pkt, offset, &data, &len);
		xenvif_rx_copy_add(queue, req, offset, data, len);

		offset += len;
		pkt->remaining_len -= len;

	} while (offset < XEN_PAGE_SIZE && pkt->remaining_len > 0);

	if (pkt->remaining_len > 0)
		flags = XEN_NETRXF_more_data;
	else
		flags = 0;

	if (pkt->slot == 0) {
		struct sk_buff *skb = pkt->skb;

		if (skb->ip_summed == CHECKSUM_PARTIAL)
			flags |= XEN_NETRXF_csum_blank |
				 XEN_NETRXF_data_validated;
		else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
			flags |= XEN_NETRXF_data_validated;

		if (pkt->extra_count != 0)
			flags |= XEN_NETRXF_extra_info;
	}

	rsp->offset = 0;
	rsp->flags = flags;
	rsp->id = req->id;
	rsp->status = (s16)offset;
}

static void xenvif_rx_extra_slot(struct xenvif_queue *queue,
				 struct xenvif_pkt_state *pkt,
				 struct xen_netif_rx_request *req,
				 struct xen_netif_rx_response *rsp)
{
	struct xen_netif_extra_info *extra = (void *)rsp;
	unsigned int i;

	pkt->extra_count--;

	for (i = 0; i < ARRAY_SIZE(pkt->extras); i++) {
		if (pkt->extras[i].type) {
			*extra = pkt->extras[i];

			if (pkt->extra_count != 0)
				extra->flags |= XEN_NETIF_EXTRA_FLAG_MORE;

			pkt->extras[i].type = 0;
			return;
		}
	}
	BUG();
}

static void xenvif_rx_skb(struct xenvif_queue *queue)
{
	struct xenvif_pkt_state pkt;

	xenvif_rx_next_skb(queue, &pkt);

	queue->last_rx_time = jiffies;

	do {
		struct xen_netif_rx_request *req;
		struct xen_netif_rx_response *rsp;

		req = RING_GET_REQUEST(&queue->rx, queue->rx.req_cons);
		rsp = RING_GET_RESPONSE(&queue->rx, queue->rx.req_cons);

		/* Extras must go after the first data slot */
		if (pkt.slot != 0 && pkt.extra_count != 0)
			xenvif_rx_extra_slot(queue, &pkt, req, rsp);
		else
			xenvif_rx_data_slot(queue, &pkt, req, rsp);

		queue->rx.req_cons++;
		pkt.slot++;
	} while (pkt.remaining_len > 0 || pkt.extra_count != 0);

	xenvif_rx_complete(queue, &pkt);
}

#define RX_BATCH_SIZE 64

void xenvif_rx_action(struct xenvif_queue *queue)
{
	struct sk_buff_head completed_skbs;
	unsigned int work_done = 0;

	__skb_queue_head_init(&completed_skbs);
	queue->rx_copy.completed = &completed_skbs;

	while (xenvif_rx_ring_slots_available(queue) &&
	       !skb_queue_empty(&queue->rx_queue) &&
	       work_done < RX_BATCH_SIZE) {
		xenvif_rx_skb(queue);
		work_done++;
	}

	/* Flush any pending copies and complete all skbs. */
	xenvif_rx_copy_flush(queue);
}

static RING_IDX xenvif_rx_queue_slots(const struct xenvif_queue *queue)
{
	RING_IDX prod, cons;

	prod = queue->rx.sring->req_prod;
	cons = queue->rx.req_cons;

	return prod - cons;
}

static bool xenvif_rx_queue_stalled(const struct xenvif_queue *queue)
{
	unsigned int needed = READ_ONCE(queue->rx_slots_needed);

	return !queue->stalled &&
		xenvif_rx_queue_slots(queue) < needed &&
		time_after(jiffies,
			   queue->last_rx_time + queue->vif->stall_timeout);
}

static bool xenvif_rx_queue_ready(struct xenvif_queue *queue)
{
	unsigned int needed = READ_ONCE(queue->rx_slots_needed);

	return queue->stalled && xenvif_rx_queue_slots(queue) >= needed;
}

bool xenvif_have_rx_work(struct xenvif_queue *queue, bool test_kthread)
{
	return xenvif_rx_ring_slots_available(queue) ||
		(queue->vif->stall_timeout &&
		 (xenvif_rx_queue_stalled(queue) ||
		  xenvif_rx_queue_ready(queue))) ||
		(test_kthread && kthread_should_stop()) ||
		queue->vif->disabled;
}

static long xenvif_rx_queue_timeout(struct xenvif_queue *queue)
{
	struct sk_buff *skb;
	long timeout;

	skb = skb_peek(&queue->rx_queue);
	if (!skb)
		return MAX_SCHEDULE_TIMEOUT;

	timeout = XENVIF_RX_CB(skb)->expires - jiffies;
	return timeout < 0 ? 0 : timeout;
}

/* Wait until the guest Rx thread has work.
 *
 * The timeout needs to be adjusted based on the current head of the
 * queue (and not just the head at the beginning).  In particular, if
 * the queue is initially empty an infinite timeout is used and this
 * needs to be reduced when a skb is queued.
 *
 * This cannot be done with wait_event_timeout() because it only
 * calculates the timeout once.
 */
static void xenvif_wait_for_rx_work(struct xenvif_queue *queue)
{
	DEFINE_WAIT(wait);

	if (xenvif_have_rx_work(queue, true))
		return;

	for (;;) {
		long ret;

		prepare_to_wait(&queue->wq, &wait, TASK_INTERRUPTIBLE);
		if (xenvif_have_rx_work(queue, true))
			break;
		if (atomic_fetch_andnot(NETBK_RX_EOI | NETBK_COMMON_EOI,
					&queue->eoi_pending) &
		    (NETBK_RX_EOI | NETBK_COMMON_EOI))
			xen_irq_lateeoi(queue->rx_irq, 0);

		ret = schedule_timeout(xenvif_rx_queue_timeout(queue));
		if (!ret)
			break;
	}
	finish_wait(&queue->wq, &wait);
}

static void xenvif_queue_carrier_off(struct xenvif_queue *queue)
{
	struct xenvif *vif = queue->vif;

	queue->stalled = true;

	/* At least one queue has stalled? Disable the carrier. */
	spin_lock(&vif->lock);
	if (vif->stalled_queues++ == 0) {
		netdev_info(vif->dev, "Guest Rx stalled");
		netif_carrier_off(vif->dev);
	}
	spin_unlock(&vif->lock);
}

static void xenvif_queue_carrier_on(struct xenvif_queue *queue)
{
	struct xenvif *vif = queue->vif;

	queue->last_rx_time = jiffies; /* Reset Rx stall detection. */
	queue->stalled = false;

	/* All queues are ready? Enable the carrier. */
	spin_lock(&vif->lock);
	if (--vif->stalled_queues == 0) {
		netdev_info(vif->dev, "Guest Rx ready");
		netif_carrier_on(vif->dev);
	}
	spin_unlock(&vif->lock);
}

int xenvif_kthread_guest_rx(void *data)
{
	struct xenvif_queue *queue = data;
	struct xenvif *vif = queue->vif;

	if (!vif->stall_timeout)
		xenvif_queue_carrier_on(queue);

	for (;;) {
		xenvif_wait_for_rx_work(queue);

		if (kthread_should_stop())
			break;

		/* This frontend is found to be rogue, disable it in
		 * kthread context. Currently this is only set when
		 * netback finds out frontend sends malformed packet,
		 * but we cannot disable the interface in softirq
		 * context so we defer it here, if this thread is
		 * associated with queue 0.
		 */
		if (unlikely(vif->disabled && queue->id == 0)) {
			xenvif_carrier_off(vif);
			break;
		}

		if (!skb_queue_empty(&queue->rx_queue))
			xenvif_rx_action(queue);

		/* If the guest hasn't provided any Rx slots for a
		 * while it's probably not responsive, drop the
		 * carrier so packets are dropped earlier.
		 */
		if (vif->stall_timeout) {
			if (xenvif_rx_queue_stalled(queue))
				xenvif_queue_carrier_off(queue);
			else if (xenvif_rx_queue_ready(queue))
				xenvif_queue_carrier_on(queue);
		}

		/* Queued packets may have foreign pages from other
		 * domains.  These cannot be queued indefinitely as
		 * this would starve guests of grant refs and transmit
		 * slots.
		 */
		xenvif_rx_queue_drop_expired(queue);

		cond_resched();
	}

	/* Bin any remaining skbs */
	xenvif_rx_queue_purge(queue);

	return 0;
}
Commit	Line	Data
3254f836 PD	1	/*
	2	* Copyright (c) 2016 Citrix Systems Inc.
	3	* Copyright (c) 2002-2005, K A Fraser
	4	*
	5	* This program is free software; you can redistribute it and/or
	6	* modify it under the terms of the GNU General Public License version 2
	7	* as published by the Free Software Foundation; or, when distributed
	8	* separately from the Linux kernel or incorporated into other
	9	* software packages, subject to the following license:
	10	*
	11	* Permission is hereby granted, free of charge, to any person obtaining a copy
	12	* of this source file (the "Software"), to deal in the Software without
	13	* restriction, including without limitation the rights to use, copy, modify,
	14	* merge, publish, distribute, sublicense, and/or sell copies of the Software,
	15	* and to permit persons to whom the Software is furnished to do so, subject to
	16	* the following conditions:
	17	*
	18	* The above copyright notice and this permission notice shall be included in
	19	* all copies or substantial portions of the Software.
	20	*
	21	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	22	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	23	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	24	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	25	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
	26	* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
	27	* IN THE SOFTWARE.
	28	*/
3254f836 PD	29	#include "common.h"
	30
	31	#include <linux/kthread.h>
	32
	33	#include <xen/xen.h>
	34	#include <xen/events.h>
	35
6032046e JG	36	/*
	37	* Update the needed ring page slots for the first SKB queued.
	38	* Note that any call sequence outside the RX thread calling this function
	39	* needs to wake up the RX thread via a call of xenvif_kick_thread()
	40	* afterwards in order to avoid a race with putting the thread to sleep.
	41	*/
	42	static void xenvif_update_needed_slots(struct xenvif_queue *queue,
	43	const struct sk_buff *skb)
3254f836	44	{
6032046e	45	unsigned int needed = 0;
3254f836	46
6032046e JG	47	if (skb) {
	48	needed = DIV_ROUND_UP(skb->len, XEN_PAGE_SIZE);
	49	if (skb_is_gso(skb))
	50	needed++;
	51	if (skb->sw_hash)
	52	needed++;
ec7d8e7d	53	}
3254f836	54
6032046e JG	55	WRITE_ONCE(queue->rx_slots_needed, needed);
6032046e JG	56	}
3254f836	57
6032046e JG	58	static bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue)
	59	{
	60	RING_IDX prod, cons;
	61	unsigned int needed;
	62
	63	needed = READ_ONCE(queue->rx_slots_needed);
	64	if (!needed)
	65	return false;
ec7d8e7d	66
3254f836 PD	67	do {
	68	prod = queue->rx.sring->req_prod;
	69	cons = queue->rx.req_cons;
	70
	71	if (prod - cons >= needed)
	72	return true;
	73
	74	queue->rx.sring->req_event = prod + 1;
	75
	76	/* Make sure event is visible before we check prod
	77	* again.
	78	*/
	79	mb();
	80	} while (queue->rx.sring->req_prod != prod);
	81
	82	return false;
	83	}
	84
	85	void xenvif_rx_queue_tail(struct xenvif_queue queue, struct sk_buff skb)
	86	{
	87	unsigned long flags;
	88
	89	spin_lock_irqsave(&queue->rx_queue.lock, flags);
	90
be81992f	91	if (queue->rx_queue_len >= queue->rx_queue_max) {
3254f836 PD	92	struct net_device *dev = queue->vif->dev;
	93
	94	netif_tx_stop_queue(netdev_get_tx_queue(dev, queue->id));
be81992f JG	95	kfree_skb(skb);
	96	queue->vif->dev->stats.rx_dropped++;
	97	} else {
	98	if (skb_queue_empty(&queue->rx_queue))
	99	xenvif_update_needed_slots(queue, skb);
	100
	101	__skb_queue_tail(&queue->rx_queue, skb);
	102
	103	queue->rx_queue_len += skb->len;
3254f836 PD	104	}
	105
	106	spin_unlock_irqrestore(&queue->rx_queue.lock, flags);
	107	}
	108
	109	static struct sk_buff xenvif_rx_dequeue(struct xenvif_queue queue)
	110	{
	111	struct sk_buff *skb;
	112
	113	spin_lock_irq(&queue->rx_queue.lock);
	114
	115	skb = __skb_dequeue(&queue->rx_queue);
7c0b1a23	116	if (skb) {
6032046e JG	117	xenvif_update_needed_slots(queue, skb_peek(&queue->rx_queue));
6032046e JG	118
3254f836	119	queue->rx_queue_len -= skb->len;
7c0b1a23 DV	120	if (queue->rx_queue_len < queue->rx_queue_max) {
7c0b1a23 DV	121	struct netdev_queue *txq;
3254f836	122
7c0b1a23 DV	123	txq = netdev_get_tx_queue(queue->vif->dev, queue->id);
	124	netif_tx_wake_queue(txq);
	125	}
3254f836 PD	126	}
	127
	128	spin_unlock_irq(&queue->rx_queue.lock);
7c0b1a23 DV	129
7c0b1a23 DV	130	return skb;
3254f836 PD	131	}
	132
	133	static void xenvif_rx_queue_purge(struct xenvif_queue *queue)
	134	{
	135	struct sk_buff *skb;
	136
	137	while ((skb = xenvif_rx_dequeue(queue)) != NULL)
	138	kfree_skb(skb);
	139	}
	140
	141	static void xenvif_rx_queue_drop_expired(struct xenvif_queue *queue)
	142	{
	143	struct sk_buff *skb;
	144
	145	for (;;) {
	146	skb = skb_peek(&queue->rx_queue);
	147	if (!skb)
	148	break;
	149	if (time_before(jiffies, XENVIF_RX_CB(skb)->expires))
	150	break;
	151	xenvif_rx_dequeue(queue);
	152	kfree_skb(skb);
be81992f	153	queue->vif->dev->stats.rx_dropped++;
3254f836 PD	154	}
	155	}
	156
eb1723a2	157	static void xenvif_rx_copy_flush(struct xenvif_queue *queue)
3254f836	158	{
eb1723a2	159	unsigned int i;
a37f1229	160	int notify;
3254f836	161
eb1723a2	162	gnttab_batch_copy(queue->rx_copy.op, queue->rx_copy.num);
3254f836	163
eb1723a2 DV	164	for (i = 0; i < queue->rx_copy.num; i++) {
eb1723a2 DV	165	struct gnttab_copy *op;
3254f836	166
eb1723a2	167	op = &queue->rx_copy.op[i];
3254f836	168
eb1723a2 DV	169	/* If the copy failed, overwrite the status field in
	170	* the corresponding response.
	171	*/
	172	if (unlikely(op->status != GNTST_okay)) {
	173	struct xen_netif_rx_response *rsp;
3254f836	174
eb1723a2 DV	175	rsp = RING_GET_RESPONSE(&queue->rx,
	176	queue->rx_copy.idx[i]);
	177	rsp->status = op->status;
	178	}
	179	}
3254f836	180
eb1723a2	181	queue->rx_copy.num = 0;
a37f1229 DV	182
	183	/* Push responses for all completed packets. */
	184	RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->rx, notify);
	185	if (notify)
	186	notify_remote_via_irq(queue->rx_irq);
	187
	188	__skb_queue_purge(queue->rx_copy.completed);
eb1723a2	189	}
3254f836	190
eb1723a2 DV	191	static void xenvif_rx_copy_add(struct xenvif_queue *queue,
	192	struct xen_netif_rx_request *req,
	193	unsigned int offset, void *data, size_t len)
3254f836	194	{
eb1723a2 DV	195	struct gnttab_copy *op;
eb1723a2 DV	196	struct page *page;
3254f836	197	struct xen_page_foreign *foreign;
3254f836	198
eb1723a2 DV	199	if (queue->rx_copy.num == COPY_BATCH_SIZE)
eb1723a2 DV	200	xenvif_rx_copy_flush(queue);
3254f836	201
eb1723a2	202	op = &queue->rx_copy.op[queue->rx_copy.num];
3254f836	203
eb1723a2	204	page = virt_to_page(data);
3254f836	205
eb1723a2	206	op->flags = GNTCOPY_dest_gref;
3254f836 PD	207
	208	foreign = xen_page_foreign(page);
	209	if (foreign) {
eb1723a2 DV	210	op->source.domid = foreign->domid;
	211	op->source.u.ref = foreign->gref;
	212	op->flags \|= GNTCOPY_source_gref;
3254f836	213	} else {
eb1723a2 DV	214	op->source.u.gmfn = virt_to_gfn(data);
eb1723a2 DV	215	op->source.domid = DOMID_SELF;
3254f836	216	}
3254f836	217
eb1723a2 DV	218	op->source.offset = xen_offset_in_page(data);
	219	op->dest.u.ref = req->gref;
	220	op->dest.domid = queue->vif->domid;
	221	op->dest.offset = offset;
	222	op->len = len;
3254f836	223
eb1723a2 DV	224	queue->rx_copy.idx[queue->rx_copy.num] = queue->rx.req_cons;
eb1723a2 DV	225	queue->rx_copy.num++;
3254f836 PD	226	}
3254f836 PD	227
eb1723a2	228	static unsigned int xenvif_gso_type(struct sk_buff *skb)
3254f836	229	{
3254f836 PD	230	if (skb_is_gso(skb)) {
3254f836 PD	231	if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
eb1723a2 DV	232	return XEN_NETIF_GSO_TYPE_TCPV4;
	233	else
	234	return XEN_NETIF_GSO_TYPE_TCPV6;
3254f836	235	}
eb1723a2 DV	236	return XEN_NETIF_GSO_TYPE_NONE;
eb1723a2 DV	237	}
3254f836	238
eb1723a2 DV	239	struct xenvif_pkt_state {
	240	struct sk_buff *skb;
	241	size_t remaining_len;
2167ca02 RL	242	struct sk_buff *frag_iter;
2167ca02 RL	243	int frag; /* frag == -1 => frag_iter->head */
eb1723a2 DV	244	unsigned int frag_offset;
	245	struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX - 1];
	246	unsigned int extra_count;
	247	unsigned int slot;
	248	};
3254f836	249
eb1723a2 DV	250	static void xenvif_rx_next_skb(struct xenvif_queue *queue,
	251	struct xenvif_pkt_state *pkt)
	252	{
	253	struct sk_buff *skb;
	254	unsigned int gso_type;
3254f836	255
eb1723a2	256	skb = xenvif_rx_dequeue(queue);
3254f836	257
eb1723a2 DV	258	queue->stats.tx_bytes += skb->len;
eb1723a2 DV	259	queue->stats.tx_packets++;
3254f836	260
eb1723a2 DV	261	/* Reset packet state. */
eb1723a2 DV	262	memset(pkt, 0, sizeof(struct xenvif_pkt_state));
3254f836	263
eb1723a2	264	pkt->skb = skb;
2167ca02	265	pkt->frag_iter = skb;
eb1723a2 DV	266	pkt->remaining_len = skb->len;
eb1723a2 DV	267	pkt->frag = -1;
3254f836	268
eb1723a2 DV	269	gso_type = xenvif_gso_type(skb);
	270	if ((1 << gso_type) & queue->vif->gso_mask) {
	271	struct xen_netif_extra_info *extra;
3254f836	272
eb1723a2	273	extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
3254f836	274
eb1723a2 DV	275	extra->u.gso.type = gso_type;
	276	extra->u.gso.size = skb_shinfo(skb)->gso_size;
	277	extra->u.gso.pad = 0;
	278	extra->u.gso.features = 0;
	279	extra->type = XEN_NETIF_EXTRA_TYPE_GSO;
	280	extra->flags = 0;
3254f836	281
eb1723a2	282	pkt->extra_count++;
3254f836 PD	283	}
3254f836 PD	284
1c9535c7 DK	285	if (queue->vif->xdp_headroom) {
	286	struct xen_netif_extra_info *extra;
	287
	288	extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_XDP - 1];
	289
	290	memset(extra, 0, sizeof(struct xen_netif_extra_info));
	291	extra->u.xdp.headroom = queue->vif->xdp_headroom;
	292	extra->type = XEN_NETIF_EXTRA_TYPE_XDP;
	293	extra->flags = 0;
	294
	295	pkt->extra_count++;
	296	}
	297
eb1723a2 DV	298	if (skb->sw_hash) {
eb1723a2 DV	299	struct xen_netif_extra_info *extra;
3254f836	300
eb1723a2	301	extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_HASH - 1];
3254f836	302
eb1723a2 DV	303	extra->u.hash.algorithm =
eb1723a2 DV	304	XEN_NETIF_CTRL_HASH_ALGORITHM_TOEPLITZ;
3254f836	305
eb1723a2 DV	306	if (skb->l4_hash)
	307	extra->u.hash.type =
	308	skb->protocol == htons(ETH_P_IP) ?
	309	_XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP :
	310	_XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP;
	311	else
	312	extra->u.hash.type =
	313	skb->protocol == htons(ETH_P_IP) ?
	314	_XEN_NETIF_CTRL_HASH_TYPE_IPV4 :
	315	_XEN_NETIF_CTRL_HASH_TYPE_IPV6;
3254f836	316
eb1723a2	317	(uint32_t )extra->u.hash.value = skb_get_hash_raw(skb);
3254f836	318
eb1723a2 DV	319	extra->type = XEN_NETIF_EXTRA_TYPE_HASH;
eb1723a2 DV	320	extra->flags = 0;
3254f836	321
eb1723a2	322	pkt->extra_count++;
3254f836	323	}
3254f836 PD	324	}
3254f836 PD	325
eb1723a2 DV	326	static void xenvif_rx_complete(struct xenvif_queue *queue,
eb1723a2 DV	327	struct xenvif_pkt_state *pkt)
3254f836	328	{
a37f1229	329	/* All responses are ready to be pushed. */
eb1723a2	330	queue->rx.rsp_prod_pvt = queue->rx.req_cons;
3254f836	331
a37f1229	332	__skb_queue_tail(queue->rx_copy.completed, pkt->skb);
3254f836 PD	333	}
3254f836 PD	334
2167ca02 RL	335	static void xenvif_rx_next_frag(struct xenvif_pkt_state *pkt)
	336	{
	337	struct sk_buff *frag_iter = pkt->frag_iter;
	338	unsigned int nr_frags = skb_shinfo(frag_iter)->nr_frags;
	339
	340	pkt->frag++;
	341	pkt->frag_offset = 0;
	342
	343	if (pkt->frag >= nr_frags) {
	344	if (frag_iter == pkt->skb)
	345	pkt->frag_iter = skb_shinfo(frag_iter)->frag_list;
	346	else
	347	pkt->frag_iter = frag_iter->next;
	348
	349	pkt->frag = -1;
	350	}
	351	}
	352
eb1723a2 DV	353	static void xenvif_rx_next_chunk(struct xenvif_queue *queue,
	354	struct xenvif_pkt_state *pkt,
	355	unsigned int offset, void **data,
	356	size_t *len)
3254f836	357	{
2167ca02	358	struct sk_buff *frag_iter = pkt->frag_iter;
eb1723a2 DV	359	void *frag_data;
eb1723a2 DV	360	size_t frag_len, chunk_len;
3254f836	361
2167ca02 RL	362	BUG_ON(!frag_iter);
2167ca02 RL	363
eb1723a2	364	if (pkt->frag == -1) {
2167ca02 RL	365	frag_data = frag_iter->data;
2167ca02 RL	366	frag_len = skb_headlen(frag_iter);
eb1723a2	367	} else {
2167ca02	368	skb_frag_t *frag = &skb_shinfo(frag_iter)->frags[pkt->frag];
3254f836	369
eb1723a2 DV	370	frag_data = skb_frag_address(frag);
eb1723a2 DV	371	frag_len = skb_frag_size(frag);
3254f836	372	}
3254f836	373
eb1723a2 DV	374	frag_data += pkt->frag_offset;
eb1723a2 DV	375	frag_len -= pkt->frag_offset;
3254f836	376
f112be65 AB	377	chunk_len = min_t(size_t, frag_len, XEN_PAGE_SIZE - offset);
	378	chunk_len = min_t(size_t, chunk_len, XEN_PAGE_SIZE -
	379	xen_offset_in_page(frag_data));
3254f836	380
eb1723a2	381	pkt->frag_offset += chunk_len;
3254f836	382
eb1723a2	383	/* Advance to next frag? */
2167ca02 RL	384	if (frag_len == chunk_len)
2167ca02 RL	385	xenvif_rx_next_frag(pkt);
3254f836	386
eb1723a2 DV	387	*data = frag_data;
	388	*len = chunk_len;
	389	}
3254f836	390
eb1723a2 DV	391	static void xenvif_rx_data_slot(struct xenvif_queue *queue,
	392	struct xenvif_pkt_state *pkt,
	393	struct xen_netif_rx_request *req,
	394	struct xen_netif_rx_response *rsp)
	395	{
1c9535c7	396	unsigned int offset = queue->vif->xdp_headroom;
eb1723a2	397	unsigned int flags;
3254f836	398
eb1723a2 DV	399	do {
	400	size_t len;
	401	void *data;
3254f836	402
eb1723a2 DV	403	xenvif_rx_next_chunk(queue, pkt, offset, &data, &len);
eb1723a2 DV	404	xenvif_rx_copy_add(queue, req, offset, data, len);
3254f836	405
eb1723a2 DV	406	offset += len;
eb1723a2 DV	407	pkt->remaining_len -= len;
3254f836	408
eb1723a2	409	} while (offset < XEN_PAGE_SIZE && pkt->remaining_len > 0);
3254f836	410
eb1723a2 DV	411	if (pkt->remaining_len > 0)
	412	flags = XEN_NETRXF_more_data;
	413	else
	414	flags = 0;
	415
	416	if (pkt->slot == 0) {
	417	struct sk_buff *skb = pkt->skb;
3254f836	418
eb1723a2	419	if (skb->ip_summed == CHECKSUM_PARTIAL)
3254f836 PD	420	flags \|= XEN_NETRXF_csum_blank \|
	421	XEN_NETRXF_data_validated;
	422	else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
3254f836 PD	423	flags \|= XEN_NETRXF_data_validated;
3254f836 PD	424
eb1723a2 DV	425	if (pkt->extra_count != 0)
	426	flags \|= XEN_NETRXF_extra_info;
	427	}
3254f836	428
eb1723a2 DV	429	rsp->offset = 0;
	430	rsp->flags = flags;
	431	rsp->id = req->id;
	432	rsp->status = (s16)offset;
	433	}
3254f836	434
eb1723a2 DV	435	static void xenvif_rx_extra_slot(struct xenvif_queue *queue,
	436	struct xenvif_pkt_state *pkt,
	437	struct xen_netif_rx_request *req,
	438	struct xen_netif_rx_response *rsp)
	439	{
	440	struct xen_netif_extra_info extra = (void )rsp;
	441	unsigned int i;
3254f836	442
eb1723a2	443	pkt->extra_count--;
3254f836	444
eb1723a2 DV	445	for (i = 0; i < ARRAY_SIZE(pkt->extras); i++) {
	446	if (pkt->extras[i].type) {
	447	*extra = pkt->extras[i];
3254f836	448
eb1723a2	449	if (pkt->extra_count != 0)
3254f836	450	extra->flags \|= XEN_NETIF_EXTRA_FLAG_MORE;
eb1723a2 DV	451
	452	pkt->extras[i].type = 0;
	453	return;
3254f836	454	}
eb1723a2 DV	455	}
	456	BUG();
	457	}
3254f836	458
ed820f47	459	static void xenvif_rx_skb(struct xenvif_queue *queue)
eb1723a2 DV	460	{
eb1723a2 DV	461	struct xenvif_pkt_state pkt;
3254f836	462
eb1723a2	463	xenvif_rx_next_skb(queue, &pkt);
3254f836	464
d1ef006d DV	465	queue->last_rx_time = jiffies;
d1ef006d DV	466
eb1723a2 DV	467	do {
	468	struct xen_netif_rx_request *req;
	469	struct xen_netif_rx_response *rsp;
3254f836	470
eb1723a2 DV	471	req = RING_GET_REQUEST(&queue->rx, queue->rx.req_cons);
eb1723a2 DV	472	rsp = RING_GET_RESPONSE(&queue->rx, queue->rx.req_cons);
3254f836	473
eb1723a2 DV	474	/* Extras must go after the first data slot */
	475	if (pkt.slot != 0 && pkt.extra_count != 0)
	476	xenvif_rx_extra_slot(queue, &pkt, req, rsp);
	477	else
	478	xenvif_rx_data_slot(queue, &pkt, req, rsp);
	479
	480	queue->rx.req_cons++;
	481	pkt.slot++;
	482	} while (pkt.remaining_len > 0 \|\| pkt.extra_count != 0);
	483
	484	xenvif_rx_complete(queue, &pkt);
3254f836 PD	485	}
3254f836 PD	486
98f6d57c DV	487	#define RX_BATCH_SIZE 64
	488
	489	void xenvif_rx_action(struct xenvif_queue *queue)
	490	{
a37f1229	491	struct sk_buff_head completed_skbs;
98f6d57c DV	492	unsigned int work_done = 0;
98f6d57c DV	493
a37f1229 DV	494	__skb_queue_head_init(&completed_skbs);
	495	queue->rx_copy.completed = &completed_skbs;
	496
98f6d57c	497	while (xenvif_rx_ring_slots_available(queue) &&
94e81006	498	!skb_queue_empty(&queue->rx_queue) &&
98f6d57c DV	499	work_done < RX_BATCH_SIZE) {
	500	xenvif_rx_skb(queue);
	501	work_done++;
	502	}
a37f1229 DV	503
	504	/* Flush any pending copies and complete all skbs. */
	505	xenvif_rx_copy_flush(queue);
98f6d57c DV	506	}
98f6d57c DV	507
6032046e	508	static RING_IDX xenvif_rx_queue_slots(const struct xenvif_queue *queue)
3254f836 PD	509	{
	510	RING_IDX prod, cons;
	511
	512	prod = queue->rx.sring->req_prod;
	513	cons = queue->rx.req_cons;
	514
6032046e JG	515	return prod - cons;
	516	}
	517
	518	static bool xenvif_rx_queue_stalled(const struct xenvif_queue *queue)
	519	{
	520	unsigned int needed = READ_ONCE(queue->rx_slots_needed);
	521
3254f836	522	return !queue->stalled &&
6032046e	523	xenvif_rx_queue_slots(queue) < needed &&
3254f836 PD	524	time_after(jiffies,
	525	queue->last_rx_time + queue->vif->stall_timeout);
	526	}
	527
	528	static bool xenvif_rx_queue_ready(struct xenvif_queue *queue)
	529	{
6032046e	530	unsigned int needed = READ_ONCE(queue->rx_slots_needed);
3254f836	531
6032046e	532	return queue->stalled && xenvif_rx_queue_slots(queue) >= needed;
3254f836 PD	533	}
3254f836 PD	534
23025393	535	bool xenvif_have_rx_work(struct xenvif_queue *queue, bool test_kthread)
3254f836 PD	536	{
	537	return xenvif_rx_ring_slots_available(queue) \|\|
	538	(queue->vif->stall_timeout &&
	539	(xenvif_rx_queue_stalled(queue) \|\|
	540	xenvif_rx_queue_ready(queue))) \|\|
23025393	541	(test_kthread && kthread_should_stop()) \|\|
3254f836 PD	542	queue->vif->disabled;
	543	}
	544
	545	static long xenvif_rx_queue_timeout(struct xenvif_queue *queue)
	546	{
	547	struct sk_buff *skb;
	548	long timeout;
	549
	550	skb = skb_peek(&queue->rx_queue);
	551	if (!skb)
	552	return MAX_SCHEDULE_TIMEOUT;
	553
	554	timeout = XENVIF_RX_CB(skb)->expires - jiffies;
	555	return timeout < 0 ? 0 : timeout;
	556	}
	557
	558	/* Wait until the guest Rx thread has work.
	559	*
	560	* The timeout needs to be adjusted based on the current head of the
	561	* queue (and not just the head at the beginning). In particular, if
	562	* the queue is initially empty an infinite timeout is used and this
	563	* needs to be reduced when a skb is queued.
	564	*
	565	* This cannot be done with wait_event_timeout() because it only
	566	* calculates the timeout once.
	567	*/
	568	static void xenvif_wait_for_rx_work(struct xenvif_queue *queue)
	569	{
	570	DEFINE_WAIT(wait);
	571
23025393	572	if (xenvif_have_rx_work(queue, true))
3254f836 PD	573	return;
	574
	575	for (;;) {
	576	long ret;
	577
	578	prepare_to_wait(&queue->wq, &wait, TASK_INTERRUPTIBLE);
23025393	579	if (xenvif_have_rx_work(queue, true))
3254f836	580	break;
23025393 JG	581	if (atomic_fetch_andnot(NETBK_RX_EOI \| NETBK_COMMON_EOI,
	582	&queue->eoi_pending) &
	583	(NETBK_RX_EOI \| NETBK_COMMON_EOI))
	584	xen_irq_lateeoi(queue->rx_irq, 0);
	585
3254f836 PD	586	ret = schedule_timeout(xenvif_rx_queue_timeout(queue));
	587	if (!ret)
	588	break;
	589	}
	590	finish_wait(&queue->wq, &wait);
	591	}
	592
	593	static void xenvif_queue_carrier_off(struct xenvif_queue *queue)
	594	{
	595	struct xenvif *vif = queue->vif;
	596
	597	queue->stalled = true;
	598
	599	/* At least one queue has stalled? Disable the carrier. */
	600	spin_lock(&vif->lock);
	601	if (vif->stalled_queues++ == 0) {
	602	netdev_info(vif->dev, "Guest Rx stalled");
	603	netif_carrier_off(vif->dev);
	604	}
	605	spin_unlock(&vif->lock);
	606	}
	607
	608	static void xenvif_queue_carrier_on(struct xenvif_queue *queue)
	609	{
	610	struct xenvif *vif = queue->vif;
	611
	612	queue->last_rx_time = jiffies; /* Reset Rx stall detection. */
	613	queue->stalled = false;
	614
	615	/* All queues are ready? Enable the carrier. */
	616	spin_lock(&vif->lock);
	617	if (--vif->stalled_queues == 0) {
	618	netdev_info(vif->dev, "Guest Rx ready");
	619	netif_carrier_on(vif->dev);
	620	}
	621	spin_unlock(&vif->lock);
	622	}
	623
	624	int xenvif_kthread_guest_rx(void *data)
	625	{
	626	struct xenvif_queue *queue = data;
	627	struct xenvif *vif = queue->vif;
	628
	629	if (!vif->stall_timeout)
	630	xenvif_queue_carrier_on(queue);
	631
	632	for (;;) {
	633	xenvif_wait_for_rx_work(queue);
	634
	635	if (kthread_should_stop())
	636	break;
	637
	638	/* This frontend is found to be rogue, disable it in
	639	* kthread context. Currently this is only set when
	640	* netback finds out frontend sends malformed packet,
	641	* but we cannot disable the interface in softirq
	642	* context so we defer it here, if this thread is
	643	* associated with queue 0.
	644	*/
	645	if (unlikely(vif->disabled && queue->id == 0)) {
	646	xenvif_carrier_off(vif);
	647	break;
	648	}
	649
650	if (!skb_queue_empty(&queue->rx_queue))
651	xenvif_rx_action(queue);
652
653	/* If the guest hasn't provided any Rx slots for a
654	* while it's probably not responsive, drop the
655	* carrier so packets are dropped earlier.
656	*/
657	if (vif->stall_timeout) {
658	if (xenvif_rx_queue_stalled(queue))
659	xenvif_queue_carrier_off(queue);
660	else if (xenvif_rx_queue_ready(queue))
661	xenvif_queue_carrier_on(queue);
662	}
663
664	/* Queued packets may have foreign pages from other
665	* domains. These cannot be queued indefinitely as
666	* this would starve guests of grant refs and transmit
667	* slots.
668	*/
669	xenvif_rx_queue_drop_expired(queue);
670
3254f836 PD	671	cond_resched();
	672	}
	673
	674	/* Bin any remaining skbs */
	675	xenvif_rx_queue_purge(queue);
	676
	677	return 0;
	678	}