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Message-ID: <20160905104738.GD31137@gauss.secunet.com>
Date: Mon, 5 Sep 2016 12:47:38 +0200
From: Steffen Klassert <steffen.klassert@...unet.com>
To: <netdev@...r.kernel.org>
CC: Alexander Duyck <alexander.h.duyck@...el.com>,
Eric Dumazet <eric.dumazet@...il.com>,
Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Subject: [PATCH net-next v3] gso: Support partial splitting at the frag_list
pointer
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@...unet.com>
---
Changes since v1:
- Use the assumption that all buffers in the chain excluding the last
containing the same amount of data.
- Simplify some checks against gso partial.
- Fix the generation of IP IDs.
Changes since v2:
- Merge common code of gso partial and frag_list pointer splitting.
net/core/skbuff.c | 50 +++++++++++++++++++++++++++++++++++++++-----------
net/ipv4/af_inet.c | 14 ++++++++++----
net/ipv4/gre_offload.c | 6 ++++--
net/ipv4/tcp_offload.c | 13 +++++++------
net/ipv4/udp_offload.c | 6 ++++--
net/ipv6/ip6_offload.c | 5 ++++-
6 files changed, 68 insertions(+), 26 deletions(-)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 3864b4b6..f754d47 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3078,11 +3078,30 @@ 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)) {
+ if (list_skb &&
+ net_gso_ok(features, skb_shinfo(head_skb)->gso_type)) {
+ struct sk_buff *iter;
+
+ /* 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;
@@ -3090,6 +3109,7 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
partial_segs = 0;
}
+normal:
headroom = skb_headroom(head_skb);
pos = skb_headlen(head_skb);
@@ -3281,21 +3301,29 @@ 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 < gso_size)
+ skb_shinfo(tail)->gso_size = 0;
+ else
+ skb_shinfo(tail)->gso_segs = DIV_ROUND_UP(tail->len, gso_size);
}
/* Following permits correct backpressure, for protocols
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index e94b47b..1effc98 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -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;
}
- tot_len = skb_shinfo(skb)->gso_size +
- SKB_GSO_CB(skb)->data_offset +
- skb->head - (unsigned char *)iph;
+
+ 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++);
diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
index ecd1e09..96e0efe 100644
--- a/net/ipv4/gre_offload.c
+++ b/net/ipv4/gre_offload.c
@@ -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
diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index 5c59649..bc68da3 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -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;
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 81f253b..f9333c9 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -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);
diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index 22e90e5..e7bfd55 100644
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -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);
--
1.9.1
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