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gso: Support partial splitting at the frag_list pointer

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Since commit 8a29111c7 ("net: gro: allow to build full sized skb")
gro may build buffers with a frag_list. This can hurt forwarding
because most NICs can't offload such packets, they need to be
segmented in software. This patch splits buffers with a frag_list
at the frag_list pointer into buffers that can be TSO offloaded.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Steffen Klassert 2016-09-19 12:58:47 +02:00 • committed by David S. Miller
parent e867e87ae8
commit 07b26c9454
6 changed files with 69 additions and 26 deletions
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51
net/core/skbuff.c
View file

@ -3097,11 +3097,31 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
sg = !!(features & NETIF_F_SG);
csum = !!can_checksum_protocol(features, proto);
/* GSO partial only requires that we trim off any excess that
* doesn't fit into an MSS sized block, so take care of that
* now.
*/
if (sg && csum && (features & NETIF_F_GSO_PARTIAL)) {
if (sg && csum && (mss != GSO_BY_FRAGS)) {
if (!(features & NETIF_F_GSO_PARTIAL)) {
struct sk_buff *iter;
if (!list_skb ||
!net_gso_ok(features, skb_shinfo(head_skb)->gso_type))
goto normal;
/* Split the buffer at the frag_list pointer.
* This is based on the assumption that all
* buffers in the chain excluding the last
* containing the same amount of data.
*/
skb_walk_frags(head_skb, iter) {
if (skb_headlen(iter))
goto normal;
len -= iter->len;
}
}
/* GSO partial only requires that we trim off any excess that
* doesn't fit into an MSS sized block, so take care of that
* now.
*/
partial_segs = len / mss;
if (partial_segs > 1)
mss *= partial_segs;
@ -3109,6 +3129,7 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
partial_segs = 0;
}
normal:
headroom = skb_headroom(head_skb);
pos = skb_headlen(head_skb);
@ -3300,21 +3321,29 @@ perform_csum_check:
*/
segs->prev = tail;
/* Update GSO info on first skb in partial sequence. */
if (partial_segs) {
struct sk_buff *iter;
int type = skb_shinfo(head_skb)->gso_type;
unsigned short gso_size = skb_shinfo(head_skb)->gso_size;
/* Update type to add partial and then remove dodgy if set */
type |= SKB_GSO_PARTIAL;
type |= (features & NETIF_F_GSO_PARTIAL) / NETIF_F_GSO_PARTIAL * SKB_GSO_PARTIAL;
type &= ~SKB_GSO_DODGY;
/* Update GSO info and prepare to start updating headers on
* our way back down the stack of protocols.
*/
skb_shinfo(segs)->gso_size = skb_shinfo(head_skb)->gso_size;
skb_shinfo(segs)->gso_segs = partial_segs;
skb_shinfo(segs)->gso_type = type;
SKB_GSO_CB(segs)->data_offset = skb_headroom(segs) + doffset;
for (iter = segs; iter; iter = iter->next) {
skb_shinfo(iter)->gso_size = gso_size;
skb_shinfo(iter)->gso_segs = partial_segs;
skb_shinfo(iter)->gso_type = type;
SKB_GSO_CB(iter)->data_offset = skb_headroom(iter) + doffset;
}
if (tail->len - doffset <= gso_size)
skb_shinfo(tail)->gso_size = 0;
else if (tail != segs)
skb_shinfo(tail)->gso_segs = DIV_ROUND_UP(tail->len - doffset, gso_size);
}
/* Following permits correct backpressure, for protocols