This is a note to let you know that I've just added the patch titled
xen-netfront: pull on receive skb may need to happen earlier
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
xen-netfront-pull-on-receive-skb-may-need-to-happen-earlier.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 093b9c71b6e450e375f4646ba86faed0195ec7df Mon Sep 17 00:00:00 2001
From: Jan Beulich <[email protected]>
Date: Wed, 17 Jul 2013 08:09:37 +0100
Subject: xen-netfront: pull on receive skb may need to happen earlier
From: Jan Beulich <[email protected]>
commit 093b9c71b6e450e375f4646ba86faed0195ec7df upstream.
Due to commit 3683243b ("xen-netfront: use __pskb_pull_tail to ensure
linear area is big enough on RX") xennet_fill_frags() may end up
filling MAX_SKB_FRAGS + 1 fragments in a receive skb, and only reduce
the fragment count subsequently via __pskb_pull_tail(). That's a
result of xennet_get_responses() allowing a maximum of one more slot to
be consumed (and intermediately transformed into a fragment) if the
head slot has a size less than or equal to RX_COPY_THRESHOLD.
Hence we need to adjust xennet_fill_frags() to pull earlier if we
reached the maximum fragment count - due to the described behavior of
xennet_get_responses() this guarantees that at least the first fragment
will get completely consumed, and hence the fragment count reduced.
In order to not needlessly call __pskb_pull_tail() twice, make the
original call conditional upon the pull target not having been reached
yet, and defer the newly added one as much as possible (an alternative
would have been to always call the function right before the call to
xennet_fill_frags(), but that would imply more frequent cases of
needing to call it twice).
Signed-off-by: Jan Beulich <[email protected]>
Acked-by: Wei Liu <[email protected]>
Cc: Ian Campbell <[email protected]>
Acked-by: Ian Campbell <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/net/xen-netfront.c | 31 +++++++++++++------------------
1 file changed, 13 insertions(+), 18 deletions(-)
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -276,8 +276,7 @@ no_skb:
break;
}
- __skb_fill_page_desc(skb, 0, page, 0, 0);
- skb_shinfo(skb)->nr_frags = 1;
+ skb_add_rx_frag(skb, 0, page, 0, 0, PAGE_SIZE);
__skb_queue_tail(&np->rx_batch, skb);
}
@@ -822,7 +821,6 @@ static RING_IDX xennet_fill_frags(struct
struct sk_buff_head *list)
{
struct skb_shared_info *shinfo = skb_shinfo(skb);
- int nr_frags = shinfo->nr_frags;
RING_IDX cons = np->rx.rsp_cons;
struct sk_buff *nskb;
@@ -831,19 +829,21 @@ static RING_IDX xennet_fill_frags(struct
RING_GET_RESPONSE(&np->rx, ++cons);
skb_frag_t *nfrag = &skb_shinfo(nskb)->frags[0];
- __skb_fill_page_desc(skb, nr_frags,
- skb_frag_page(nfrag),
- rx->offset, rx->status);
+ if (shinfo->nr_frags == MAX_SKB_FRAGS) {
+ unsigned int pull_to = NETFRONT_SKB_CB(skb)->pull_to;
- skb->data_len += rx->status;
+ BUG_ON(pull_to <= skb_headlen(skb));
+ __pskb_pull_tail(skb, pull_to - skb_headlen(skb));
+ }
+ BUG_ON(shinfo->nr_frags >= MAX_SKB_FRAGS);
+
+ skb_add_rx_frag(skb, shinfo->nr_frags, skb_frag_page(nfrag),
+ rx->offset, rx->status, PAGE_SIZE);
skb_shinfo(nskb)->nr_frags = 0;
kfree_skb(nskb);
-
- nr_frags++;
}
- shinfo->nr_frags = nr_frags;
return cons;
}
@@ -929,7 +929,8 @@ static int handle_incoming_queue(struct
while ((skb = __skb_dequeue(rxq)) != NULL) {
int pull_to = NETFRONT_SKB_CB(skb)->pull_to;
- __pskb_pull_tail(skb, pull_to - skb_headlen(skb));
+ if (pull_to > skb_headlen(skb))
+ __pskb_pull_tail(skb, pull_to - skb_headlen(skb));
/* Ethernet work: Delayed to here as it peeks the header. */
skb->protocol = eth_type_trans(skb, dev);
@@ -1015,16 +1016,10 @@ err:
skb_shinfo(skb)->frags[0].page_offset = rx->offset;
skb_frag_size_set(&skb_shinfo(skb)->frags[0], rx->status);
skb->data_len = rx->status;
+ skb->len += rx->status;
i = xennet_fill_frags(np, skb, &tmpq);
- /*
- * Truesize is the actual allocation size, even if the
- * allocation is only partially used.
- */
- skb->truesize += PAGE_SIZE * skb_shinfo(skb)->nr_frags;
- skb->len += skb->data_len;
-
if (rx->flags & XEN_NETRXF_csum_blank)
skb->ip_summed = CHECKSUM_PARTIAL;
else if (rx->flags & XEN_NETRXF_data_validated)
Patches currently in stable-queue which might be from [email protected] are
queue-3.10/xen-netfront-pull-on-receive-skb-may-need-to-happen-earlier.patch
queue-3.10/xen-blkback-check-device-permissions-before-allowing-op_discard.patch
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