diff mbox

[v4,net-next] net: introduce dev_set_forwarding()

Message ID 20131110140540.GA1413@gondor.apana.org.au
State RFC, archived
Delegated to: David Miller
Headers show

Commit Message

Herbert Xu Nov. 10, 2013, 2:05 p.m. UTC 
On Thu, Nov 07, 2013 at 08:25:30PM -0800, Eric Dumazet wrote:
> On Fri, 2013-11-08 at 11:59 +0800, Herbert Xu wrote:
> 
> > However, I still have one reason for preferring my patch, it'll
> > be easier to prodce TSO packets with it.  Let me see if I can
> > fix up the arbitrary frag boundary issue without making it too
> > ugly.
> 
> Sure !

I ended up giving up on the recursion idea and borrowed your
iterative approach.  I haven't yet had the chance to test it
yet but here is the WIP.

The main assumptions are that virtio_net frag_list is always non-
linear and GRO frag_list may only contain a linear head part that
is exactly MSS bytes long.


Cheers,
diff mbox

Patch

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 3735fad..fab44ff 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2776,6 +2776,7 @@  struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features)
 	struct sk_buff *segs = NULL;
 	struct sk_buff *tail = NULL;
 	struct sk_buff *fskb = skb_shinfo(skb)->frag_list;
+	skb_frag_t *skb_frag = skb_shinfo(skb)->frags;
 	unsigned int mss = skb_shinfo(skb)->gso_size;
 	unsigned int doffset = skb->data - skb_mac_header(skb);
 	unsigned int offset = doffset;
@@ -2815,16 +2816,23 @@  struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features)
 		if (hsize > len || !sg)
 			hsize = len;
 
-		if (!hsize && i >= nfrags) {
-			BUG_ON(fskb->len != len);
+		if (!hsize && i >= nfrags && skb_headlen(fskb)) {
+			BUG_ON(skb_headlen(fskb) != len);
 
 			pos += len;
+			i = 0;
+			nfrags = skb_shinfo(fskb)->nr_frags;
+			skb_frag = skb_shinfo(fskb)->frags;
+
 			nskb = skb_clone(fskb, GFP_ATOMIC);
 			fskb = fskb->next;
 
 			if (unlikely(!nskb))
 				goto err;
 
+			if (unlikely(pskb_trim(nskb, len)))
+				goto err;
+
 			hsize = skb_end_offset(nskb);
 			if (skb_cow_head(nskb, doffset + headroom)) {
 				kfree_skb(nskb);
@@ -2861,7 +2869,8 @@  struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features)
 						 nskb->data - tnl_hlen,
 						 doffset + tnl_hlen);
 
-		if (fskb != skb_shinfo(skb)->frag_list)
+		if (fskb != skb_shinfo(skb)->frag_list &&
+		    nskb->len == len + doffset)
 			goto perform_csum_check;
 
 		if (!sg) {
@@ -2879,8 +2888,20 @@  struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features)
 
 		skb_shinfo(nskb)->tx_flags = skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
 
-		while (pos < offset + len && i < nfrags) {
-			*frag = skb_shinfo(skb)->frags[i];
+		while (pos < offset + len) {
+			if (i >= nfrags) {
+				BUG_ON(skb_headlen(fskb));
+
+				i = 0;
+				nfrags = skb_shinfo(fskb)->nr_frags;
+				skb_frag = skb_shinfo(fskb)->frags;
+
+				BUG_ON(!nfrags);
+
+				fskb = fskb->next;
+			}
+
+			*frag = *skb_frag;
 			__skb_frag_ref(frag);
 			size = skb_frag_size(frag);
 
@@ -2891,37 +2912,26 @@  struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features)
 
 			skb_shinfo(nskb)->nr_frags++;
 
-			if (pos + size <= offset + len) {
-				i++;
-				pos += size;
-			} else {
-				skb_frag_size_sub(frag, pos + size - (offset + len));
-				goto skip_fraglist;
+			if (pos + size >= offset + len) {
+				skb_frag_size_sub(frag,
+						  pos + size - (offset + len));
+				break;
 			}
 
+			skb_frag++;
+			i++;
+			pos += size;
 			frag++;
-		}
-
-		if (pos < offset + len) {
-			struct sk_buff *fskb2 = fskb;
 
-			BUG_ON(pos + fskb->len != offset + len);
-
-			pos += fskb->len;
-			fskb = fskb->next;
-
-			if (fskb2->next) {
-				fskb2 = skb_clone(fskb2, GFP_ATOMIC);
-				if (!fskb2)
-					goto err;
-			} else
-				skb_get(fskb2);
-
-			SKB_FRAG_ASSERT(nskb);
-			skb_shinfo(nskb)->frag_list = fskb2;
+			if (unlikely(skb_shinfo(nskb)->nr_frags >=
+				     MAX_SKB_FRAGS)) {
+				net_warn_ratelimited(
+					"skb_segment: too many frags: %u %u\n",
+					pos, mss);
+				goto err;
+			}
 		}
 
-skip_fraglist:
 		nskb->data_len = len - hsize;
 		nskb->len += nskb->data_len;
 		nskb->truesize += nskb->data_len;