Mailing List Archive

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>
---
v2: Only move to next frame if there is data remaining.
---
drivers/net/xen-netback/netback.c | 40 ++++++++++++++++++++++++++++++++----
1 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 4ebfcf3..f2d6b78 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -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++;
--
1.7.2.5


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