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xen-netback: Use skb->cb for pending_idx
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Storing the pending_idx at the first byte of the linear buffer never looked
good, skb->cb is a more proper place for this. It also prevents the header to
be directly grant copied there, and we don't have the pending_idx after we
copied the header here, so it's time to change it.
It also introduces helpers for the RX side

Signed-off-by: Zoltan Kiss <zoltan.kiss@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Zoltan Kiss authored and David S. Miller committed Mar 7, 2014
1 parent 31c70d5 commit 8f13dd9
Showing 1 changed file with 25 additions and 17 deletions.
42 changes: 25 additions & 17 deletions drivers/net/xen-netback/netback.c
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Original file line number Diff line number Diff line change
Expand Up @@ -455,10 +455,12 @@ static void xenvif_add_frag_responses(struct xenvif *vif, int status,
}
}

struct skb_cb_overlay {
struct xenvif_rx_cb {
int meta_slots_used;
};

#define XENVIF_RX_CB(skb) ((struct xenvif_rx_cb *)(skb)->cb)

void xenvif_kick_thread(struct xenvif *vif)
{
wake_up(&vif->wq);
Expand All @@ -474,7 +476,6 @@ static void xenvif_rx_action(struct xenvif *vif)
LIST_HEAD(notify);
int ret;
unsigned long offset;
struct skb_cb_overlay *sco;
bool need_to_notify = false;

struct netrx_pending_operations npo = {
Expand Down Expand Up @@ -513,9 +514,8 @@ static void xenvif_rx_action(struct xenvif *vif)
} else
vif->rx_last_skb_slots = 0;

sco = (struct skb_cb_overlay *)skb->cb;
sco->meta_slots_used = xenvif_gop_skb(skb, &npo);
BUG_ON(sco->meta_slots_used > max_slots_needed);
XENVIF_RX_CB(skb)->meta_slots_used = xenvif_gop_skb(skb, &npo);
BUG_ON(XENVIF_RX_CB(skb)->meta_slots_used > max_slots_needed);

__skb_queue_tail(&rxq, skb);
}
Expand All @@ -529,7 +529,6 @@ static void xenvif_rx_action(struct xenvif *vif)
gnttab_batch_copy(vif->grant_copy_op, npo.copy_prod);

while ((skb = __skb_dequeue(&rxq)) != NULL) {
sco = (struct skb_cb_overlay *)skb->cb;

if ((1 << vif->meta[npo.meta_cons].gso_type) &
vif->gso_prefix_mask) {
Expand All @@ -540,19 +539,21 @@ static void xenvif_rx_action(struct xenvif *vif)

resp->offset = vif->meta[npo.meta_cons].gso_size;
resp->id = vif->meta[npo.meta_cons].id;
resp->status = sco->meta_slots_used;
resp->status = XENVIF_RX_CB(skb)->meta_slots_used;

npo.meta_cons++;
sco->meta_slots_used--;
XENVIF_RX_CB(skb)->meta_slots_used--;
}


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

status = xenvif_check_gop(vif, sco->meta_slots_used, &npo);
status = xenvif_check_gop(vif,
XENVIF_RX_CB(skb)->meta_slots_used,
&npo);

if (sco->meta_slots_used == 1)
if (XENVIF_RX_CB(skb)->meta_slots_used == 1)
flags = 0;
else
flags = XEN_NETRXF_more_data;
Expand Down Expand Up @@ -589,13 +590,13 @@ static void xenvif_rx_action(struct xenvif *vif)

xenvif_add_frag_responses(vif, status,
vif->meta + npo.meta_cons + 1,
sco->meta_slots_used);
XENVIF_RX_CB(skb)->meta_slots_used);

RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&vif->rx, ret);

need_to_notify |= !!ret;

npo.meta_cons += sco->meta_slots_used;
npo.meta_cons += XENVIF_RX_CB(skb)->meta_slots_used;
dev_kfree_skb(skb);
}

Expand Down Expand Up @@ -772,14 +773,21 @@ static struct page *xenvif_alloc_page(struct xenvif *vif,
return page;
}


struct xenvif_tx_cb {
u16 pending_idx;
};

#define XENVIF_TX_CB(skb) ((struct xenvif_tx_cb *)(skb)->cb)

static struct gnttab_copy *xenvif_get_requests(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;
u16 pending_idx = *((u16 *)skb->data);
u16 pending_idx = XENVIF_TX_CB(skb)->pending_idx;
u16 head_idx = 0;
int slot, start;
struct page *page;
Expand Down Expand Up @@ -897,7 +905,7 @@ static int xenvif_tx_check_gop(struct xenvif *vif,
struct gnttab_copy **gopp)
{
struct gnttab_copy *gop = *gopp;
u16 pending_idx = *((u16 *)skb->data);
u16 pending_idx = XENVIF_TX_CB(skb)->pending_idx;
struct skb_shared_info *shinfo = skb_shinfo(skb);
struct pending_tx_info *tx_info;
int nr_frags = shinfo->nr_frags;
Expand Down Expand Up @@ -944,7 +952,7 @@ static int xenvif_tx_check_gop(struct xenvif *vif,
continue;

/* First error: invalidate header and preceding fragments. */
pending_idx = *((u16 *)skb->data);
pending_idx = XENVIF_TX_CB(skb)->pending_idx;
xenvif_idx_release(vif, pending_idx, XEN_NETIF_RSP_OKAY);
for (j = start; j < i; j++) {
pending_idx = frag_get_pending_idx(&shinfo->frags[j]);
Expand Down Expand Up @@ -1236,7 +1244,7 @@ static unsigned xenvif_tx_build_gops(struct xenvif *vif, int budget)
memcpy(&vif->pending_tx_info[pending_idx].req,
&txreq, sizeof(txreq));
vif->pending_tx_info[pending_idx].head = index;
*((u16 *)skb->data) = pending_idx;
XENVIF_TX_CB(skb)->pending_idx = pending_idx;

__skb_put(skb, data_len);

Expand Down Expand Up @@ -1283,7 +1291,7 @@ static int xenvif_tx_submit(struct xenvif *vif)
u16 pending_idx;
unsigned data_len;

pending_idx = *((u16 *)skb->data);
pending_idx = XENVIF_TX_CB(skb)->pending_idx;
txp = &vif->pending_tx_info[pending_idx].req;

/* Check the remap error code. */
Expand Down

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