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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
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

43
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);
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.
*/
if (sg && csum && (features & NETIF_F_GSO_PARTIAL)) {
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 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
*/
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

8
net/ipv4/af_inet.c
View file

@ -1192,7 +1192,7 @@ EXPORT_SYMBOL(inet_sk_rebuild_header);
struct sk_buff *inet_gso_segment(struct sk_buff *skb,
netdev_features_t features)
{
bool udpfrag = false, fixedid = false, encap;
bool udpfrag = false, fixedid = false, gso_partial, encap;
struct sk_buff *segs = ERR_PTR(-EINVAL);
const struct net_offload *ops;
unsigned int offset = 0;
@ -1245,6 +1245,8 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
if (IS_ERR_OR_NULL(segs))
goto out;
gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
skb = segs;
do {
iph = (struct iphdr *)(skb_mac_header(skb) + nhoff);
@ -1259,9 +1261,13 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
iph->id = htons(id);
id += skb_shinfo(skb)->gso_segs;
}
if (gso_partial)
tot_len = skb_shinfo(skb)->gso_size +
SKB_GSO_CB(skb)->data_offset +
skb->head - (unsigned char *)iph;
else
tot_len = skb->len - nhoff;
} else {
if (!fixedid)
iph->id = htons(id++);

6
net/ipv4/gre_offload.c
View file

@ -24,7 +24,7 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
__be16 protocol = skb->protocol;
u16 mac_len = skb->mac_len;
int gre_offset, outer_hlen;
bool need_csum, ufo;
bool need_csum, ufo, gso_partial;
if (!skb->encapsulation)
goto out;
@ -69,6 +69,8 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
goto out;
}
gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
outer_hlen = skb_tnl_header_len(skb);
gre_offset = outer_hlen - tnl_hlen;
skb = segs;
@ -96,7 +98,7 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
greh = (struct gre_base_hdr *)skb_transport_header(skb);
pcsum = (__sum16 *)(greh + 1);
if (skb_is_gso(skb)) {
if (gso_partial) {
unsigned int partial_adj;
/* Adjust checksum to account for the fact that

13
net/ipv4/tcp_offload.c
View file

@ -90,12 +90,6 @@ struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
goto out;
}
/* GSO partial only requires splitting the frame into an MSS
* multiple and possibly a remainder. So update the mss now.
*/
if (features & NETIF_F_GSO_PARTIAL)
mss = skb->len - (skb->len % mss);
copy_destructor = gso_skb->destructor == tcp_wfree;
ooo_okay = gso_skb->ooo_okay;
/* All segments but the first should have ooo_okay cleared */
@ -108,6 +102,13 @@ struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
/* Only first segment might have ooo_okay set */
segs->ooo_okay = ooo_okay;
/* GSO partial and frag_list segmentation only requires splitting
* the frame into an MSS multiple and possibly a remainder, both
* cases return a GSO skb. So update the mss now.
*/
if (skb_is_gso(segs))
mss *= skb_shinfo(segs)->gso_segs;
delta = htonl(oldlen + (thlen + mss));
skb = segs;

6
net/ipv4/udp_offload.c
View file

@ -21,7 +21,7 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
__be16 new_protocol, bool is_ipv6)
{
int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
bool remcsum, need_csum, offload_csum, ufo;
bool remcsum, need_csum, offload_csum, ufo, gso_partial;
struct sk_buff *segs = ERR_PTR(-EINVAL);
struct udphdr *uh = udp_hdr(skb);
u16 mac_offset = skb->mac_header;
@ -88,6 +88,8 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
goto out;
}
gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
outer_hlen = skb_tnl_header_len(skb);
udp_offset = outer_hlen - tnl_hlen;
skb = segs;
@ -117,7 +119,7 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
* will be using a length value equal to only one MSS sized
* segment instead of the entire frame.
*/
if (skb_is_gso(skb)) {
if (gso_partial) {
uh->len = htons(skb_shinfo(skb)->gso_size +
SKB_GSO_CB(skb)->data_offset +
skb->head - (unsigned char *)uh);

5
net/ipv6/ip6_offload.c
View file

@ -69,6 +69,7 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
int offset = 0;
bool encap, udpfrag;
int nhoff;
bool gso_partial;
skb_reset_network_header(skb);
nhoff = skb_network_header(skb) - skb_mac_header(skb);
@ -101,9 +102,11 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
if (IS_ERR(segs))
goto out;
gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
for (skb = segs; skb; skb = skb->next) {
ipv6h = (struct ipv6hdr *)(skb_mac_header(skb) + nhoff);
if (skb_is_gso(skb))
if (gso_partial)
payload_len = skb_shinfo(skb)->gso_size +
SKB_GSO_CB(skb)->data_offset +
skb->head - (unsigned char *)(ipv6h + 1);