net: Add frag_list support to skb_segment
This patch adds limited support for handling frag_list packets in skb_segment. The intention is to support GRO (Generic Receive Offload) packets which will be constructed by chaining normal packets using frag_list. As such we require all frag_list members terminate on exact MSS boundaries. This is checked using BUG_ON. As there should only be one producer in the kernel of such packets, namely GRO, this requirement should not be difficult to maintain. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Родитель
eb14f01959
Коммит
89319d3801
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@ -2428,6 +2428,7 @@ struct sk_buff *skb_segment(struct sk_buff *skb, int features)
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{
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struct sk_buff *segs = NULL;
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struct sk_buff *tail = NULL;
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struct sk_buff *fskb = skb_shinfo(skb)->frag_list;
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unsigned int mss = skb_shinfo(skb)->gso_size;
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unsigned int doffset = skb->data - skb_mac_header(skb);
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unsigned int offset = doffset;
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@ -2447,7 +2448,6 @@ struct sk_buff *skb_segment(struct sk_buff *skb, int features)
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struct sk_buff *nskb;
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skb_frag_t *frag;
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int hsize;
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int k;
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int size;
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len = skb->len - offset;
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@ -2460,9 +2460,36 @@ struct sk_buff *skb_segment(struct sk_buff *skb, int features)
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if (hsize > len || !sg)
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hsize = len;
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nskb = alloc_skb(hsize + doffset + headroom, GFP_ATOMIC);
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if (unlikely(!nskb))
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goto err;
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if (!hsize && i >= nfrags) {
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BUG_ON(fskb->len != len);
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pos += len;
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nskb = skb_clone(fskb, GFP_ATOMIC);
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fskb = fskb->next;
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if (unlikely(!nskb))
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goto err;
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hsize = skb_end_pointer(nskb) - nskb->head;
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if (skb_cow_head(nskb, doffset + headroom)) {
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kfree_skb(nskb);
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goto err;
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}
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nskb->truesize += skb_end_pointer(nskb) - nskb->head -
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hsize;
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skb_release_head_state(nskb);
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__skb_push(nskb, doffset);
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} else {
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nskb = alloc_skb(hsize + doffset + headroom,
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GFP_ATOMIC);
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if (unlikely(!nskb))
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goto err;
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skb_reserve(nskb, headroom);
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__skb_put(nskb, doffset);
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}
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if (segs)
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tail->next = nskb;
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@ -2473,13 +2500,15 @@ struct sk_buff *skb_segment(struct sk_buff *skb, int features)
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__copy_skb_header(nskb, skb);
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nskb->mac_len = skb->mac_len;
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skb_reserve(nskb, headroom);
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skb_reset_mac_header(nskb);
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skb_set_network_header(nskb, skb->mac_len);
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nskb->transport_header = (nskb->network_header +
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skb_network_header_len(skb));
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skb_copy_from_linear_data(skb, skb_put(nskb, doffset),
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doffset);
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skb_copy_from_linear_data(skb, nskb->data, doffset);
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if (pos >= offset + len)
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continue;
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if (!sg) {
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nskb->ip_summed = CHECKSUM_NONE;
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nskb->csum = skb_copy_and_csum_bits(skb, offset,
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@ -2489,14 +2518,11 @@ struct sk_buff *skb_segment(struct sk_buff *skb, int features)
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}
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frag = skb_shinfo(nskb)->frags;
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k = 0;
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skb_copy_from_linear_data_offset(skb, offset,
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skb_put(nskb, hsize), hsize);
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while (pos < offset + len) {
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BUG_ON(i >= nfrags);
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while (pos < offset + len && i < nfrags) {
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*frag = skb_shinfo(skb)->frags[i];
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get_page(frag->page);
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size = frag->size;
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@ -2506,20 +2532,39 @@ struct sk_buff *skb_segment(struct sk_buff *skb, int features)
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frag->size -= offset - pos;
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}
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k++;
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skb_shinfo(nskb)->nr_frags++;
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if (pos + size <= offset + len) {
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i++;
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pos += size;
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} else {
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frag->size -= pos + size - (offset + len);
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break;
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goto skip_fraglist;
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}
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frag++;
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}
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skb_shinfo(nskb)->nr_frags = k;
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if (pos < offset + len) {
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struct sk_buff *fskb2 = fskb;
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BUG_ON(pos + fskb->len != offset + len);
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pos += fskb->len;
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fskb = fskb->next;
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if (fskb2->next) {
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fskb2 = skb_clone(fskb2, GFP_ATOMIC);
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if (!fskb2)
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goto err;
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} else
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skb_get(fskb2);
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BUG_ON(skb_shinfo(nskb)->frag_list);
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skb_shinfo(nskb)->frag_list = fskb2;
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}
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skip_fraglist:
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nskb->data_len = len - hsize;
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nskb->len += nskb->data_len;
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nskb->truesize += nskb->data_len;
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