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xen: netback: handle compound page fragments on transmit. 

An SKB paged fragment can consist of a compound page with order > 0.
However the netchannel protocol deals only in PAGE_SIZE frames.

Handle this in netbk_gop_frag_copy and xen_netbk_count_skb_slots by
iterating over the frames which make up the page.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Konrad Rzeszutek Wilk <konrad@kernel.org>
Cc: Sander Eikelenboom <linux@eikelenboom.it>
Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ian Campbell 2012-10-10 03:48:42 +00:00 committed by David S. Miller
parent 6caab7b054
commit 6a8ed462f1
1 changed files with 35 additions and 5 deletions
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40
drivers/net/xen-netback/netback.c
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@ -335,21 +335,35 @@ unsigned int xen_netbk_count_skb_slots(struct xenvif *vif, struct sk_buff *skb)
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
unsigned long size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
unsigned long offset = skb_shinfo(skb)->frags[i].page_offset;
unsigned long bytes;
offset &= ~PAGE_MASK;
while (size > 0) {
BUG_ON(offset >= PAGE_SIZE);
BUG_ON(copy_off > MAX_BUFFER_OFFSET);
if (start_new_rx_buffer(copy_off, size, 0)) {
bytes = PAGE_SIZE - offset;
if (bytes > size)
bytes = size;
if (start_new_rx_buffer(copy_off, bytes, 0)) {
count++;
copy_off = 0;
}
bytes = size;
if (copy_off + bytes > MAX_BUFFER_OFFSET)
bytes = MAX_BUFFER_OFFSET - copy_off;
copy_off += bytes;
offset += bytes;
size -= bytes;
if (offset == PAGE_SIZE)
offset = 0;
}
}
return count;
@ -403,14 +417,24 @@ static void netbk_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
unsigned long bytes;
/* Data must not cross a page boundary. */
BUG_ON(size + offset > PAGE_SIZE);
BUG_ON(size + offset > PAGE_SIZE<<compound_order(page));
meta = npo->meta + npo->meta_prod - 1;
/* Skip unused frames from start of page */
page += offset >> PAGE_SHIFT;
offset &= ~PAGE_MASK;
while (size > 0) {
BUG_ON(offset >= PAGE_SIZE);
BUG_ON(npo->copy_off > MAX_BUFFER_OFFSET);
if (start_new_rx_buffer(npo->copy_off, size, *head)) {
bytes = PAGE_SIZE - offset;
if (bytes > size)
bytes = size;
if (start_new_rx_buffer(npo->copy_off, bytes, *head)) {
/*
* Netfront requires there to be some data in the head
* buffer.
@ -420,7 +444,6 @@ static void netbk_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
meta = get_next_rx_buffer(vif, npo);
}
bytes = size;
if (npo->copy_off + bytes > MAX_BUFFER_OFFSET)
bytes = MAX_BUFFER_OFFSET - npo->copy_off;
@ -453,6 +476,13 @@ static void netbk_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
offset += bytes;
size -= bytes;
/* Next frame */
if (offset == PAGE_SIZE && size) {
BUG_ON(!PageCompound(page));
page++;
offset = 0;
}
/* Leave a gap for the GSO descriptor. */
if (*head && skb_shinfo(skb)->gso_size && !vif->gso_prefix)
vif->rx.req_cons++;