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Commit 6a8ed462 authored by Ian Campbell's avatar Ian Campbell Committed by David S. Miller
Browse files

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: default avatarIan 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: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6caab7b0

drivers/net/xen-netback/netback.c

+35 −5
Original line number Diff line number Diff line
@@ -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++;