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Merge branch 'xen-netfront-next'
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David Vrabel says:

====================
xen-netfront: refactor making Tx requests

As netfront as evolved to handle different sorts of skbs the code to
fill a Tx requests has been copy and pasted several times.  The series
refactors this and a few other areas.

The first patch is to a Xen header but this can be merged via
net-next.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
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David S. Miller committed Jan 14, 2015
2 parents 933685c + a55e8bb commit 6a38cc2
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Showing 2 changed files with 79 additions and 120 deletions.
194 changes: 74 additions & 120 deletions drivers/net/xen-netfront.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -421,109 +421,68 @@ static void xennet_tx_buf_gc(struct netfront_queue *queue)
xennet_maybe_wake_tx(queue);
}

static void xennet_make_frags(struct sk_buff *skb, struct netfront_queue *queue,
struct xen_netif_tx_request *tx)
{
char *data = skb->data;
unsigned long mfn;
RING_IDX prod = queue->tx.req_prod_pvt;
int frags = skb_shinfo(skb)->nr_frags;
unsigned int offset = offset_in_page(data);
unsigned int len = skb_headlen(skb);
static struct xen_netif_tx_request *xennet_make_one_txreq(
struct netfront_queue *queue, struct sk_buff *skb,
struct page *page, unsigned int offset, unsigned int len)
{
unsigned int id;
struct xen_netif_tx_request *tx;
grant_ref_t ref;
int i;

/* While the header overlaps a page boundary (including being
larger than a page), split it it into page-sized chunks. */
while (len > PAGE_SIZE - offset) {
tx->size = PAGE_SIZE - offset;
tx->flags |= XEN_NETTXF_more_data;
len -= tx->size;
data += tx->size;
offset = 0;
len = min_t(unsigned int, PAGE_SIZE - offset, len);

id = get_id_from_freelist(&queue->tx_skb_freelist, queue->tx_skbs);
queue->tx_skbs[id].skb = skb_get(skb);
tx = RING_GET_REQUEST(&queue->tx, prod++);
tx->id = id;
ref = gnttab_claim_grant_reference(&queue->gref_tx_head);
BUG_ON((signed short)ref < 0);
id = get_id_from_freelist(&queue->tx_skb_freelist, queue->tx_skbs);
tx = RING_GET_REQUEST(&queue->tx, queue->tx.req_prod_pvt++);
ref = gnttab_claim_grant_reference(&queue->gref_tx_head);
BUG_ON((signed short)ref < 0);

mfn = virt_to_mfn(data);
gnttab_grant_foreign_access_ref(ref, queue->info->xbdev->otherend_id,
mfn, GNTMAP_readonly);
gnttab_grant_foreign_access_ref(ref, queue->info->xbdev->otherend_id,
page_to_mfn(page), GNTMAP_readonly);

queue->grant_tx_page[id] = virt_to_page(data);
tx->gref = queue->grant_tx_ref[id] = ref;
tx->offset = offset;
tx->size = len;
tx->flags = 0;
}
queue->tx_skbs[id].skb = skb;
queue->grant_tx_page[id] = page;
queue->grant_tx_ref[id] = ref;

/* Grant backend access to each skb fragment page. */
for (i = 0; i < frags; i++) {
skb_frag_t *frag = skb_shinfo(skb)->frags + i;
struct page *page = skb_frag_page(frag);
tx->id = id;
tx->gref = ref;
tx->offset = offset;
tx->size = len;
tx->flags = 0;

len = skb_frag_size(frag);
offset = frag->page_offset;
return tx;
}

/* Skip unused frames from start of page */
page += offset >> PAGE_SHIFT;
offset &= ~PAGE_MASK;
static struct xen_netif_tx_request *xennet_make_txreqs(
struct netfront_queue *queue, struct xen_netif_tx_request *tx,
struct sk_buff *skb, struct page *page,
unsigned int offset, unsigned int len)
{
/* Skip unused frames from start of page */
page += offset >> PAGE_SHIFT;
offset &= ~PAGE_MASK;

while (len > 0) {
unsigned long bytes;

bytes = PAGE_SIZE - offset;
if (bytes > len)
bytes = len;

tx->flags |= XEN_NETTXF_more_data;

id = get_id_from_freelist(&queue->tx_skb_freelist,
queue->tx_skbs);
queue->tx_skbs[id].skb = skb_get(skb);
tx = RING_GET_REQUEST(&queue->tx, prod++);
tx->id = id;
ref = gnttab_claim_grant_reference(&queue->gref_tx_head);
BUG_ON((signed short)ref < 0);

mfn = pfn_to_mfn(page_to_pfn(page));
gnttab_grant_foreign_access_ref(ref,
queue->info->xbdev->otherend_id,
mfn, GNTMAP_readonly);

queue->grant_tx_page[id] = page;
tx->gref = queue->grant_tx_ref[id] = ref;
tx->offset = offset;
tx->size = bytes;
tx->flags = 0;

offset += bytes;
len -= bytes;

/* Next frame */
if (offset == PAGE_SIZE && len) {
BUG_ON(!PageCompound(page));
page++;
offset = 0;
}
}
while (len) {
tx->flags |= XEN_NETTXF_more_data;
tx = xennet_make_one_txreq(queue, skb_get(skb),
page, offset, len);
page++;
offset = 0;
len -= tx->size;
}

queue->tx.req_prod_pvt = prod;
return tx;
}

/*
* Count how many ring slots are required to send the frags of this
* skb. Each frag might be a compound page.
* Count how many ring slots are required to send this skb. Each frag
* might be a compound page.
*/
static int xennet_count_skb_frag_slots(struct sk_buff *skb)
static int xennet_count_skb_slots(struct sk_buff *skb)
{
int i, frags = skb_shinfo(skb)->nr_frags;
int pages = 0;
int pages;

pages = PFN_UP(offset_in_page(skb->data) + skb_headlen(skb));

for (i = 0; i < frags; i++) {
skb_frag_t *frag = skb_shinfo(skb)->frags + i;
Expand Down Expand Up @@ -559,18 +518,15 @@ static u16 xennet_select_queue(struct net_device *dev, struct sk_buff *skb,

static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
unsigned short id;
struct netfront_info *np = netdev_priv(dev);
struct netfront_stats *stats = this_cpu_ptr(np->stats);
struct xen_netif_tx_request *tx;
char *data = skb->data;
RING_IDX i;
grant_ref_t ref;
unsigned long mfn;
struct xen_netif_tx_request *tx, *first_tx;
unsigned int i;
int notify;
int slots;
unsigned int offset = offset_in_page(data);
unsigned int len = skb_headlen(skb);
struct page *page;
unsigned int offset;
unsigned int len;
unsigned long flags;
struct netfront_queue *queue = NULL;
unsigned int num_queues = dev->real_num_tx_queues;
Expand All @@ -593,18 +549,18 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
goto drop;
}

slots = DIV_ROUND_UP(offset + len, PAGE_SIZE) +
xennet_count_skb_frag_slots(skb);
slots = xennet_count_skb_slots(skb);
if (unlikely(slots > MAX_SKB_FRAGS + 1)) {
net_dbg_ratelimited("xennet: skb rides the rocket: %d slots, %d bytes\n",
slots, skb->len);
if (skb_linearize(skb))
goto drop;
data = skb->data;
offset = offset_in_page(data);
len = skb_headlen(skb);
}

page = virt_to_page(skb->data);
offset = offset_in_page(skb->data);
len = skb_headlen(skb);

spin_lock_irqsave(&queue->tx_lock, flags);

if (unlikely(!netif_carrier_ok(dev) ||
Expand All @@ -614,37 +570,26 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
goto drop;
}

i = queue->tx.req_prod_pvt;

id = get_id_from_freelist(&queue->tx_skb_freelist, queue->tx_skbs);
queue->tx_skbs[id].skb = skb;

tx = RING_GET_REQUEST(&queue->tx, i);
/* First request for the linear area. */
first_tx = tx = xennet_make_one_txreq(queue, skb,
page, offset, len);
page++;
offset = 0;
len -= tx->size;

tx->id = id;
ref = gnttab_claim_grant_reference(&queue->gref_tx_head);
BUG_ON((signed short)ref < 0);
mfn = virt_to_mfn(data);
gnttab_grant_foreign_access_ref(
ref, queue->info->xbdev->otherend_id, mfn, GNTMAP_readonly);
queue->grant_tx_page[id] = virt_to_page(data);
tx->gref = queue->grant_tx_ref[id] = ref;
tx->offset = offset;
tx->size = len;

tx->flags = 0;
if (skb->ip_summed == CHECKSUM_PARTIAL)
/* local packet? */
tx->flags |= XEN_NETTXF_csum_blank | XEN_NETTXF_data_validated;
else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
/* remote but checksummed. */
tx->flags |= XEN_NETTXF_data_validated;

/* Optional extra info after the first request. */
if (skb_shinfo(skb)->gso_size) {
struct xen_netif_extra_info *gso;

gso = (struct xen_netif_extra_info *)
RING_GET_REQUEST(&queue->tx, ++i);
RING_GET_REQUEST(&queue->tx, queue->tx.req_prod_pvt++);

tx->flags |= XEN_NETTXF_extra_info;

Expand All @@ -659,10 +604,19 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
gso->flags = 0;
}

queue->tx.req_prod_pvt = i + 1;
/* Requests for the rest of the linear area. */
tx = xennet_make_txreqs(queue, tx, skb, page, offset, len);

/* Requests for all the frags. */
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
tx = xennet_make_txreqs(queue, tx, skb,
skb_frag_page(frag), frag->page_offset,
skb_frag_size(frag));
}

xennet_make_frags(skb, queue, tx);
tx->size = skb->len;
/* First request has the packet length. */
first_tx->size = skb->len;

RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&queue->tx, notify);
if (notify)
Expand Down
5 changes: 5 additions & 0 deletions include/xen/page.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,11 @@

#include <asm/xen/page.h>

static inline unsigned long page_to_mfn(struct page *page)
{
return pfn_to_mfn(page_to_pfn(page));
}

struct xen_memory_region {
phys_addr_t start;
phys_addr_t size;
Expand Down

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