[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH net-next] xen-netback: fix xenvif_count_skb_slots()
On Fri, Oct 04, 2013 at 05:26:23PM +0100, Paul Durrant wrote: > Commit 4f0581d25827d5e864bcf07b05d73d0d12a20a5c introduced an error into > xenvif_count_skb_slots() for skbs with a linear area spanning a page > boundary. The alignment of skb->data needs to be taken into account, not > just the head length. This patch fixes the issue by dry-running the code > from xenvif_gop_skb() (and adjusting the comment above the function to note > that). > > Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx> > Cc: Xi Xiong <xixiong@xxxxxxxxxx> > Cc: Matt Wilson <msw@xxxxxxxxxx> > Cc: Annie Li <annie.li@xxxxxxxxxx> > Cc: Wei Liu <wei.liu2@xxxxxxxxxx> > Cc: Ian Campbell <Ian.Campbell@xxxxxxxxxx> Paul, can you reconcile this change with the one made by Simon in cs 8f985b4f7a5394c8f8725a5109451a541ddb9eea? --msw > --- > drivers/net/xen-netback/netback.c | 17 +++++++++++++++-- > 1 file changed, 15 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/xen-netback/netback.c > b/drivers/net/xen-netback/netback.c > index d0b0feb..6f680f4 100644 > --- a/drivers/net/xen-netback/netback.c > +++ b/drivers/net/xen-netback/netback.c > @@ -223,15 +223,28 @@ static bool start_new_rx_buffer(int offset, unsigned > long size, int head) > /* > * Figure out how many ring slots we're going to need to send @skb to > * the guest. This function is essentially a dry run of > - * xenvif_gop_frag_copy. > + * xenvif_gop_skb. > */ > unsigned int xenvif_count_skb_slots(struct xenvif *vif, struct sk_buff *skb) > { > + unsigned char *data; > unsigned int count; > int i, copy_off; > struct skb_cb_overlay *sco; > > - count = DIV_ROUND_UP(skb_headlen(skb), PAGE_SIZE); > + count = 0; > + > + data = skb->data; > + while (data < skb_tail_pointer(skb)) { > + unsigned int offset = offset_in_page(data); > + unsigned int len = PAGE_SIZE - offset; > + > + if (data + len > skb_tail_pointer(skb)) > + len = skb_tail_pointer(skb) - data; > + > + count++; > + data += len; > + } > > copy_off = skb_headlen(skb) % PAGE_SIZE; > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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