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netback.c
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/*
* Back-end of the driver for virtual network devices. This portion of the
* driver exports a 'unified' network-device interface that can be accessed
* by any operating system that implements a compatible front end. A
* reference front-end implementation can be found in:
* drivers/net/xen-netfront.c
*
* 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 <linux/if_vlan.h>
#include <linux/udp.h>
#include <net/tcp.h>
#include <xen/events.h>
#include <xen/interface/memory.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/page.h>
struct pending_tx_info {
struct xen_netif_tx_request req;
struct xenvif *vif;
};
typedef unsigned int pending_ring_idx_t;
struct netbk_rx_meta {
int id;
int size;
int gso_size;
};
#define MAX_PENDING_REQS 256
#define MAX_BUFFER_OFFSET PAGE_SIZE
/* extra field used in struct page */
union page_ext {
struct {
#if BITS_PER_LONG < 64
#define IDX_WIDTH 8
#define GROUP_WIDTH (BITS_PER_LONG - IDX_WIDTH)
unsigned int group:GROUP_WIDTH;
unsigned int idx:IDX_WIDTH;
#else
unsigned int group, idx;
#endif
} e;
void *mapping;
};
struct xen_netbk {
wait_queue_head_t wq;
struct task_struct *task;
struct sk_buff_head rx_queue;
struct sk_buff_head tx_queue;
struct timer_list net_timer;
struct page *mmap_pages[MAX_PENDING_REQS];
pending_ring_idx_t pending_prod;
pending_ring_idx_t pending_cons;
struct list_head net_schedule_list;
/* Protect the net_schedule_list in netif. */
spinlock_t net_schedule_list_lock;
atomic_t netfront_count;
struct pending_tx_info pending_tx_info[MAX_PENDING_REQS];
struct gnttab_copy tx_copy_ops[MAX_PENDING_REQS];
u16 pending_ring[MAX_PENDING_REQS];
/*
* Given MAX_BUFFER_OFFSET of 4096 the worst case is that each
* head/fragment page uses 2 copy operations because it
* straddles two buffers in the frontend.
*/
struct gnttab_copy grant_copy_op[2*XEN_NETIF_RX_RING_SIZE];
struct netbk_rx_meta meta[2*XEN_NETIF_RX_RING_SIZE];
};
static struct xen_netbk *xen_netbk;
static int xen_netbk_group_nr;
void xen_netbk_add_xenvif(struct xenvif *vif)
{
int i;
int min_netfront_count;
int min_group = 0;
struct xen_netbk *netbk;
min_netfront_count = atomic_read(&xen_netbk[0].netfront_count);
for (i = 0; i < xen_netbk_group_nr; i++) {
int netfront_count = atomic_read(&xen_netbk[i].netfront_count);
if (netfront_count < min_netfront_count) {
min_group = i;
min_netfront_count = netfront_count;
}
}
netbk = &xen_netbk[min_group];
vif->netbk = netbk;
atomic_inc(&netbk->netfront_count);
}
void xen_netbk_remove_xenvif(struct xenvif *vif)
{
struct xen_netbk *netbk = vif->netbk;
vif->netbk = NULL;
atomic_dec(&netbk->netfront_count);
}
static void xen_netbk_idx_release(struct xen_netbk *netbk, u16 pending_idx);
static void make_tx_response(struct xenvif *vif,
struct xen_netif_tx_request *txp,
s8 st);
static struct xen_netif_rx_response *make_rx_response(struct xenvif *vif,
u16 id,
s8 st,
u16 offset,
u16 size,
u16 flags);
static inline unsigned long idx_to_pfn(struct xen_netbk *netbk,
unsigned int idx)
{
return page_to_pfn(netbk->mmap_pages[idx]);
}
static inline unsigned long idx_to_kaddr(struct xen_netbk *netbk,
unsigned int idx)
{
return (unsigned long)pfn_to_kaddr(idx_to_pfn(netbk, idx));
}
/* extra field used in struct page */
static inline void set_page_ext(struct page *pg, struct xen_netbk *netbk,
unsigned int idx)
{
unsigned int group = netbk - xen_netbk;
union page_ext ext = { .e = { .group = group + 1, .idx = idx } };
BUILD_BUG_ON(sizeof(ext) > sizeof(ext.mapping));
pg->mapping = ext.mapping;
}
static int get_page_ext(struct page *pg,
unsigned int *pgroup, unsigned int *pidx)
{
union page_ext ext = { .mapping = pg->mapping };
struct xen_netbk *netbk;
unsigned int group, idx;
group = ext.e.group - 1;
if (group < 0 || group >= xen_netbk_group_nr)
return 0;
netbk = &xen_netbk[group];
idx = ext.e.idx;
if ((idx < 0) || (idx >= MAX_PENDING_REQS))
return 0;
if (netbk->mmap_pages[idx] != pg)
return 0;
*pgroup = group;
*pidx = idx;
return 1;
}
/*
* This is the amount of packet we copy rather than map, so that the
* guest can't fiddle with the contents of the headers while we do
* packet processing on them (netfilter, routing, etc).
*/
#define PKT_PROT_LEN (ETH_HLEN + \
VLAN_HLEN + \
sizeof(struct iphdr) + MAX_IPOPTLEN + \
sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE)
static inline pending_ring_idx_t pending_index(unsigned i)
{
return i & (MAX_PENDING_REQS-1);
}
static inline pending_ring_idx_t nr_pending_reqs(struct xen_netbk *netbk)
{
return MAX_PENDING_REQS -
netbk->pending_prod + netbk->pending_cons;
}
static void xen_netbk_kick_thread(struct xen_netbk *netbk)
{
wake_up(&netbk->wq);
}
static int max_required_rx_slots(struct xenvif *vif)
{
int max = DIV_ROUND_UP(vif->dev->mtu, PAGE_SIZE);
if (vif->can_sg || vif->gso || vif->gso_prefix)
max += MAX_SKB_FRAGS + 1; /* extra_info + frags */
return max;
}
int xen_netbk_rx_ring_full(struct xenvif *vif)
{
RING_IDX peek = vif->rx_req_cons_peek;
RING_IDX needed = max_required_rx_slots(vif);
return ((vif->rx.sring->req_prod - peek) < needed) ||
((vif->rx.rsp_prod_pvt + XEN_NETIF_RX_RING_SIZE - peek) < needed);
}
int xen_netbk_must_stop_queue(struct xenvif *vif)
{
if (!xen_netbk_rx_ring_full(vif))
return 0;
vif->rx.sring->req_event = vif->rx_req_cons_peek +
max_required_rx_slots(vif);
mb(); /* request notification /then/ check the queue */
return xen_netbk_rx_ring_full(vif);
}
/*
* Returns true if we should start a new receive buffer instead of
* adding 'size' bytes to a buffer which currently contains 'offset'
* bytes.
*/
static bool start_new_rx_buffer(int offset, unsigned long size, int head)
{
/* simple case: we have completely filled the current buffer. */
if (offset == MAX_BUFFER_OFFSET)
return true;
/*
* complex case: start a fresh buffer if the current frag
* would overflow the current buffer but only if:
* (i) this frag would fit completely in the next buffer
* and (ii) there is already some data in the current buffer
* and (iii) this is not the head buffer.
*
* Where:
* - (i) stops us splitting a frag into two copies
* unless the frag is too large for a single buffer.
* - (ii) stops us from leaving a buffer pointlessly empty.
* - (iii) stops us leaving the first buffer
* empty. Strictly speaking this is already covered
* by (ii) but is explicitly checked because
* netfront relies on the first buffer being
* non-empty and can crash otherwise.
*
* This means we will effectively linearise small
* frags but do not needlessly split large buffers
* into multiple copies tend to give large frags their
* own buffers as before.
*/
if ((offset + size > MAX_BUFFER_OFFSET) &&
(size <= MAX_BUFFER_OFFSET) && offset && !head)
return true;
return false;
}
/*
* Figure out how many ring slots we're going to need to send @skb to
* the guest. This function is essentially a dry run of
* netbk_gop_frag_copy.
*/
unsigned int xen_netbk_count_skb_slots(struct xenvif *vif, struct sk_buff *skb)
{
unsigned int count;
int i, copy_off;
count = DIV_ROUND_UP(
offset_in_page(skb->data)+skb_headlen(skb), PAGE_SIZE);
copy_off = skb_headlen(skb) % PAGE_SIZE;
if (skb_shinfo(skb)->gso_size)
count++;
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
unsigned long size = skb_shinfo(skb)->frags[i].size;
unsigned long bytes;
while (size > 0) {
BUG_ON(copy_off > MAX_BUFFER_OFFSET);
if (start_new_rx_buffer(copy_off, size, 0)) {
count++;
copy_off = 0;
}
bytes = size;
if (copy_off + bytes > MAX_BUFFER_OFFSET)
bytes = MAX_BUFFER_OFFSET - copy_off;
copy_off += bytes;
size -= bytes;
}
}
return count;
}
struct netrx_pending_operations {
unsigned copy_prod, copy_cons;
unsigned meta_prod, meta_cons;
struct gnttab_copy *copy;
struct netbk_rx_meta *meta;
int copy_off;
grant_ref_t copy_gref;
};
static struct netbk_rx_meta *get_next_rx_buffer(struct xenvif *vif,
struct netrx_pending_operations *npo)
{
struct netbk_rx_meta *meta;
struct xen_netif_rx_request *req;
req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
meta = npo->meta + npo->meta_prod++;
meta->gso_size = 0;
meta->size = 0;
meta->id = req->id;
npo->copy_off = 0;
npo->copy_gref = req->gref;
return meta;
}
/*
* Set up the grant operations for this fragment. If it's a flipping
* interface, we also set up the unmap request from here.
*/
static void netbk_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
struct netrx_pending_operations *npo,
struct page *page, unsigned long size,
unsigned long offset, int *head)
{
struct gnttab_copy *copy_gop;
struct netbk_rx_meta *meta;
/*
* These variables a used iff get_page_ext returns true,
* in which case they are guaranteed to be initialized.
*/
unsigned int uninitialized_var(group), uninitialized_var(idx);
int foreign = get_page_ext(page, &group, &idx);
unsigned long bytes;
/* Data must not cross a page boundary. */
BUG_ON(size + offset > PAGE_SIZE);
meta = npo->meta + npo->meta_prod - 1;
while (size > 0) {
BUG_ON(npo->copy_off > MAX_BUFFER_OFFSET);
if (start_new_rx_buffer(npo->copy_off, size, *head)) {
/*
* Netfront requires there to be some data in the head
* buffer.
*/
BUG_ON(*head);
meta = get_next_rx_buffer(vif, npo);
}
bytes = size;
if (npo->copy_off + bytes > MAX_BUFFER_OFFSET)
bytes = MAX_BUFFER_OFFSET - npo->copy_off;
copy_gop = npo->copy + npo->copy_prod++;
copy_gop->flags = GNTCOPY_dest_gref;
if (foreign) {
struct xen_netbk *netbk = &xen_netbk[group];
struct pending_tx_info *src_pend;
src_pend = &netbk->pending_tx_info[idx];
copy_gop->source.domid = src_pend->vif->domid;
copy_gop->source.u.ref = src_pend->req.gref;
copy_gop->flags |= GNTCOPY_source_gref;
} else {
void *vaddr = page_address(page);
copy_gop->source.domid = DOMID_SELF;
copy_gop->source.u.gmfn = virt_to_mfn(vaddr);
}
copy_gop->source.offset = offset;
copy_gop->dest.domid = vif->domid;
copy_gop->dest.offset = npo->copy_off;
copy_gop->dest.u.ref = npo->copy_gref;
copy_gop->len = bytes;
npo->copy_off += bytes;
meta->size += bytes;
offset += bytes;
size -= bytes;
/* Leave a gap for the GSO descriptor. */
if (*head && skb_shinfo(skb)->gso_size && !vif->gso_prefix)
vif->rx.req_cons++;
*head = 0; /* There must be something in this buffer now. */
}
}
/*
* Prepare an SKB to be transmitted to the frontend.
*
* This function is responsible for allocating grant operations, meta
* structures, etc.
*
* It returns the number of meta structures consumed. The number of
* ring slots used is always equal to the number of meta slots used
* plus the number of GSO descriptors used. Currently, we use either
* zero GSO descriptors (for non-GSO packets) or one descriptor (for
* frontend-side LRO).
*/
static int netbk_gop_skb(struct sk_buff *skb,
struct netrx_pending_operations *npo)
{
struct xenvif *vif = netdev_priv(skb->dev);
int nr_frags = skb_shinfo(skb)->nr_frags;
int i;
struct xen_netif_rx_request *req;
struct netbk_rx_meta *meta;
unsigned char *data;
int head = 1;
int old_meta_prod;
old_meta_prod = npo->meta_prod;
/* Set up a GSO prefix descriptor, if necessary */
if (skb_shinfo(skb)->gso_size && vif->gso_prefix) {
req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
meta = npo->meta + npo->meta_prod++;
meta->gso_size = skb_shinfo(skb)->gso_size;
meta->size = 0;
meta->id = req->id;
}
req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
meta = npo->meta + npo->meta_prod++;
if (!vif->gso_prefix)
meta->gso_size = skb_shinfo(skb)->gso_size;
else
meta->gso_size = 0;
meta->size = 0;
meta->id = req->id;
npo->copy_off = 0;
npo->copy_gref = req->gref;
data = skb->data;
while (data < skb_tail_pointer(skb)) {
unsigned int offset = offset_in_page(data);
unsigned int len = PAGE_SIZE - offset;
if (data + len > skb_tail_pointer(skb))
len = skb_tail_pointer(skb) - data;
netbk_gop_frag_copy(vif, skb, npo,
virt_to_page(data), len, offset, &head);
data += len;
}
for (i = 0; i < nr_frags; i++) {
netbk_gop_frag_copy(vif, skb, npo,
skb_shinfo(skb)->frags[i].page,
skb_shinfo(skb)->frags[i].size,
skb_shinfo(skb)->frags[i].page_offset,
&head);
}
return npo->meta_prod - old_meta_prod;
}
/*
* This is a twin to netbk_gop_skb. Assume that netbk_gop_skb was
* used to set up the operations on the top of
* netrx_pending_operations, which have since been done. Check that
* they didn't give any errors and advance over them.
*/
static int netbk_check_gop(struct xenvif *vif, int nr_meta_slots,
struct netrx_pending_operations *npo)
{
struct gnttab_copy *copy_op;
int status = XEN_NETIF_RSP_OKAY;
int i;
for (i = 0; i < nr_meta_slots; i++) {
copy_op = npo->copy + npo->copy_cons++;
if (copy_op->status != GNTST_okay) {
netdev_dbg(vif->dev,
"Bad status %d from copy to DOM%d.\n",
copy_op->status, vif->domid);
status = XEN_NETIF_RSP_ERROR;
}
}
return status;
}
static void netbk_add_frag_responses(struct xenvif *vif, int status,
struct netbk_rx_meta *meta,
int nr_meta_slots)
{
int i;
unsigned long offset;
/* No fragments used */
if (nr_meta_slots <= 1)
return;
nr_meta_slots--;
for (i = 0; i < nr_meta_slots; i++) {
int flags;
if (i == nr_meta_slots - 1)
flags = 0;
else
flags = XEN_NETRXF_more_data;
offset = 0;
make_rx_response(vif, meta[i].id, status, offset,
meta[i].size, flags);
}
}
struct skb_cb_overlay {
int meta_slots_used;
};
static void xen_netbk_rx_action(struct xen_netbk *netbk)
{
struct xenvif *vif = NULL, *tmp;
s8 status;
u16 irq, flags;
struct xen_netif_rx_response *resp;
struct sk_buff_head rxq;
struct sk_buff *skb;
LIST_HEAD(notify);
int ret;
int nr_frags;
int count;
unsigned long offset;
struct skb_cb_overlay *sco;
struct netrx_pending_operations npo = {
.copy = netbk->grant_copy_op,
.meta = netbk->meta,
};
skb_queue_head_init(&rxq);
count = 0;
while ((skb = skb_dequeue(&netbk->rx_queue)) != NULL) {
vif = netdev_priv(skb->dev);
nr_frags = skb_shinfo(skb)->nr_frags;
sco = (struct skb_cb_overlay *)skb->cb;
sco->meta_slots_used = netbk_gop_skb(skb, &npo);
count += nr_frags + 1;
__skb_queue_tail(&rxq, skb);
/* Filled the batch queue? */
if (count + MAX_SKB_FRAGS >= XEN_NETIF_RX_RING_SIZE)
break;
}
BUG_ON(npo.meta_prod > ARRAY_SIZE(netbk->meta));
if (!npo.copy_prod)
return;
BUG_ON(npo.copy_prod > ARRAY_SIZE(netbk->grant_copy_op));
ret = HYPERVISOR_grant_table_op(GNTTABOP_copy, &netbk->grant_copy_op,
npo.copy_prod);
BUG_ON(ret != 0);
while ((skb = __skb_dequeue(&rxq)) != NULL) {
sco = (struct skb_cb_overlay *)skb->cb;
vif = netdev_priv(skb->dev);
if (netbk->meta[npo.meta_cons].gso_size && vif->gso_prefix) {
resp = RING_GET_RESPONSE(&vif->rx,
vif->rx.rsp_prod_pvt++);
resp->flags = XEN_NETRXF_gso_prefix | XEN_NETRXF_more_data;
resp->offset = netbk->meta[npo.meta_cons].gso_size;
resp->id = netbk->meta[npo.meta_cons].id;
resp->status = sco->meta_slots_used;
npo.meta_cons++;
sco->meta_slots_used--;
}
vif->dev->stats.tx_bytes += skb->len;
vif->dev->stats.tx_packets++;
status = netbk_check_gop(vif, sco->meta_slots_used, &npo);
if (sco->meta_slots_used == 1)
flags = 0;
else
flags = XEN_NETRXF_more_data;
if (skb->ip_summed == CHECKSUM_PARTIAL) /* local packet? */
flags |= XEN_NETRXF_csum_blank | XEN_NETRXF_data_validated;
else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
/* remote but checksummed. */
flags |= XEN_NETRXF_data_validated;
offset = 0;
resp = make_rx_response(vif, netbk->meta[npo.meta_cons].id,
status, offset,
netbk->meta[npo.meta_cons].size,
flags);
if (netbk->meta[npo.meta_cons].gso_size && !vif->gso_prefix) {
struct xen_netif_extra_info *gso =
(struct xen_netif_extra_info *)
RING_GET_RESPONSE(&vif->rx,
vif->rx.rsp_prod_pvt++);
resp->flags |= XEN_NETRXF_extra_info;
gso->u.gso.size = netbk->meta[npo.meta_cons].gso_size;
gso->u.gso.type = XEN_NETIF_GSO_TYPE_TCPV4;
gso->u.gso.pad = 0;
gso->u.gso.features = 0;
gso->type = XEN_NETIF_EXTRA_TYPE_GSO;
gso->flags = 0;
}
netbk_add_frag_responses(vif, status,
netbk->meta + npo.meta_cons + 1,
sco->meta_slots_used);
RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&vif->rx, ret);
irq = vif->irq;
if (ret && list_empty(&vif->notify_list))
list_add_tail(&vif->notify_list, ¬ify);
xenvif_notify_tx_completion(vif);
xenvif_put(vif);
npo.meta_cons += sco->meta_slots_used;
dev_kfree_skb(skb);
}
list_for_each_entry_safe(vif, tmp, ¬ify, notify_list) {
notify_remote_via_irq(vif->irq);
list_del_init(&vif->notify_list);
}
/* More work to do? */
if (!skb_queue_empty(&netbk->rx_queue) &&
!timer_pending(&netbk->net_timer))
xen_netbk_kick_thread(netbk);
}
void xen_netbk_queue_tx_skb(struct xenvif *vif, struct sk_buff *skb)
{
struct xen_netbk *netbk = vif->netbk;
skb_queue_tail(&netbk->rx_queue, skb);
xen_netbk_kick_thread(netbk);
}
static void xen_netbk_alarm(unsigned long data)
{
struct xen_netbk *netbk = (struct xen_netbk *)data;
xen_netbk_kick_thread(netbk);
}
static int __on_net_schedule_list(struct xenvif *vif)
{
return !list_empty(&vif->schedule_list);
}
/* Must be called with net_schedule_list_lock held */
static void remove_from_net_schedule_list(struct xenvif *vif)
{
if (likely(__on_net_schedule_list(vif))) {
list_del_init(&vif->schedule_list);
xenvif_put(vif);
}
}
static struct xenvif *poll_net_schedule_list(struct xen_netbk *netbk)
{
struct xenvif *vif = NULL;
spin_lock_irq(&netbk->net_schedule_list_lock);
if (list_empty(&netbk->net_schedule_list))
goto out;
vif = list_first_entry(&netbk->net_schedule_list,
struct xenvif, schedule_list);
if (!vif)
goto out;
xenvif_get(vif);
remove_from_net_schedule_list(vif);
out:
spin_unlock_irq(&netbk->net_schedule_list_lock);
return vif;
}
void xen_netbk_schedule_xenvif(struct xenvif *vif)
{
unsigned long flags;
struct xen_netbk *netbk = vif->netbk;
if (__on_net_schedule_list(vif))
goto kick;
spin_lock_irqsave(&netbk->net_schedule_list_lock, flags);
if (!__on_net_schedule_list(vif) &&
likely(xenvif_schedulable(vif))) {
list_add_tail(&vif->schedule_list, &netbk->net_schedule_list);
xenvif_get(vif);
}
spin_unlock_irqrestore(&netbk->net_schedule_list_lock, flags);
kick:
smp_mb();
if ((nr_pending_reqs(netbk) < (MAX_PENDING_REQS/2)) &&
!list_empty(&netbk->net_schedule_list))
xen_netbk_kick_thread(netbk);
}
void xen_netbk_deschedule_xenvif(struct xenvif *vif)
{
struct xen_netbk *netbk = vif->netbk;
spin_lock_irq(&netbk->net_schedule_list_lock);
remove_from_net_schedule_list(vif);
spin_unlock_irq(&netbk->net_schedule_list_lock);
}
void xen_netbk_check_rx_xenvif(struct xenvif *vif)
{
int more_to_do;
RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, more_to_do);
if (more_to_do)
xen_netbk_schedule_xenvif(vif);
}
static void tx_add_credit(struct xenvif *vif)
{
unsigned long max_burst, max_credit;
/*
* Allow a burst big enough to transmit a jumbo packet of up to 128kB.
* Otherwise the interface can seize up due to insufficient credit.
*/
max_burst = RING_GET_REQUEST(&vif->tx, vif->tx.req_cons)->size;
max_burst = min(max_burst, 131072UL);
max_burst = max(max_burst, vif->credit_bytes);
/* Take care that adding a new chunk of credit doesn't wrap to zero. */
max_credit = vif->remaining_credit + vif->credit_bytes;
if (max_credit < vif->remaining_credit)
max_credit = ULONG_MAX; /* wrapped: clamp to ULONG_MAX */
vif->remaining_credit = min(max_credit, max_burst);
}
static void tx_credit_callback(unsigned long data)
{
struct xenvif *vif = (struct xenvif *)data;
tx_add_credit(vif);
xen_netbk_check_rx_xenvif(vif);
}
static void netbk_tx_err(struct xenvif *vif,
struct xen_netif_tx_request *txp, RING_IDX end)
{
RING_IDX cons = vif->tx.req_cons;
do {
make_tx_response(vif, txp, XEN_NETIF_RSP_ERROR);
if (cons >= end)
break;
txp = RING_GET_REQUEST(&vif->tx, cons++);
} while (1);
vif->tx.req_cons = cons;
xen_netbk_check_rx_xenvif(vif);
xenvif_put(vif);
}
static int netbk_count_requests(struct xenvif *vif,
struct xen_netif_tx_request *first,
struct xen_netif_tx_request *txp,
int work_to_do)
{
RING_IDX cons = vif->tx.req_cons;
int frags = 0;
if (!(first->flags & XEN_NETTXF_more_data))
return 0;
do {
if (frags >= work_to_do) {
netdev_dbg(vif->dev, "Need more frags\n");
return -frags;
}
if (unlikely(frags >= MAX_SKB_FRAGS)) {
netdev_dbg(vif->dev, "Too many frags\n");
return -frags;
}
memcpy(txp, RING_GET_REQUEST(&vif->tx, cons + frags),
sizeof(*txp));
if (txp->size > first->size) {
netdev_dbg(vif->dev, "Frags galore\n");
return -frags;
}
first->size -= txp->size;
frags++;
if (unlikely((txp->offset + txp->size) > PAGE_SIZE)) {
netdev_dbg(vif->dev, "txp->offset: %x, size: %u\n",
txp->offset, txp->size);
return -frags;
}
} while ((txp++)->flags & XEN_NETTXF_more_data);
return frags;
}
static struct page *xen_netbk_alloc_page(struct xen_netbk *netbk,
struct sk_buff *skb,
unsigned long pending_idx)
{
struct page *page;
page = alloc_page(GFP_KERNEL|__GFP_COLD);
if (!page)
return NULL;
set_page_ext(page, netbk, pending_idx);
netbk->mmap_pages[pending_idx] = page;
return page;
}
static struct gnttab_copy *xen_netbk_get_requests(struct xen_netbk *netbk,
struct xenvif *vif,
struct sk_buff *skb,
struct xen_netif_tx_request *txp,
struct gnttab_copy *gop)
{
struct skb_shared_info *shinfo = skb_shinfo(skb);
skb_frag_t *frags = shinfo->frags;
unsigned long pending_idx = *((u16 *)skb->data);
int i, start;
/* Skip first skb fragment if it is on same page as header fragment. */
start = ((unsigned long)shinfo->frags[0].page == pending_idx);
for (i = start; i < shinfo->nr_frags; i++, txp++) {
struct page *page;
pending_ring_idx_t index;
struct pending_tx_info *pending_tx_info =
netbk->pending_tx_info;
index = pending_index(netbk->pending_cons++);
pending_idx = netbk->pending_ring[index];
page = xen_netbk_alloc_page(netbk, skb, pending_idx);
if (!page)
return NULL;
netbk->mmap_pages[pending_idx] = page;
gop->source.u.ref = txp->gref;
gop->source.domid = vif->domid;
gop->source.offset = txp->offset;
gop->dest.u.gmfn = virt_to_mfn(page_address(page));
gop->dest.domid = DOMID_SELF;
gop->dest.offset = txp->offset;
gop->len = txp->size;
gop->flags = GNTCOPY_source_gref;
gop++;
memcpy(&pending_tx_info[pending_idx].req, txp, sizeof(*txp));
xenvif_get(vif);
pending_tx_info[pending_idx].vif = vif;
frags[i].page = (void *)pending_idx;
}
return gop;
}
static int xen_netbk_tx_check_gop(struct xen_netbk *netbk,
struct sk_buff *skb,
struct gnttab_copy **gopp)
{
struct gnttab_copy *gop = *gopp;
int pending_idx = *((u16 *)skb->data);
struct pending_tx_info *pending_tx_info = netbk->pending_tx_info;
struct xenvif *vif = pending_tx_info[pending_idx].vif;
struct xen_netif_tx_request *txp;
struct skb_shared_info *shinfo = skb_shinfo(skb);
int nr_frags = shinfo->nr_frags;
int i, err, start;
/* Check status of header. */
err = gop->status;
if (unlikely(err)) {
pending_ring_idx_t index;
index = pending_index(netbk->pending_prod++);
txp = &pending_tx_info[pending_idx].req;
make_tx_response(vif, txp, XEN_NETIF_RSP_ERROR);
netbk->pending_ring[index] = pending_idx;
xenvif_put(vif);
}
/* Skip first skb fragment if it is on same page as header fragment. */
start = ((unsigned long)shinfo->frags[0].page == pending_idx);
for (i = start; i < nr_frags; i++) {
int j, newerr;
pending_ring_idx_t index;
pending_idx = (unsigned long)shinfo->frags[i].page;
/* Check error status: if okay then remember grant handle. */
newerr = (++gop)->status;
if (likely(!newerr)) {
/* Had a previous error? Invalidate this fragment. */
if (unlikely(err))
xen_netbk_idx_release(netbk, pending_idx);
continue;
}
/* Error on this fragment: respond to client with an error. */
txp = &netbk->pending_tx_info[pending_idx].req;
make_tx_response(vif, txp, XEN_NETIF_RSP_ERROR);
index = pending_index(netbk->pending_prod++);
netbk->pending_ring[index] = pending_idx;