From 6a8ed462f16b8455eec5ae00eb6014159a6721f0 Mon Sep 17 00:00:00 2001 From: Ian Campbell Date: Wed, 10 Oct 2012 03:48:42 +0000 Subject: [PATCH] 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 Cc: Eric Dumazet Cc: Konrad Rzeszutek Wilk Cc: Sander Eikelenboom Tested-by: Konrad Rzeszutek Wilk Signed-off-by: David S. Miller --- drivers/net/xen-netback/netback.c | 40 +++++++++++++++++++++++++++---- 1 file changed, 35 insertions(+), 5 deletions(-) diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 4ebfcf3d8a3b..f2d6b78d901d 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<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++; -- 2.20.1