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@secunet.com>
Acked-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 1e329d4112426df0c2c2097ce645cf2bbc3155a7..7bf82a28e10acd0e06bd78b8ff1134d3b0e5595e 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -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

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index e94b47be0019d1b7e7b41bacbb3c52aaf254a55f..1effc986739e5d068c7ee04f614ec3f0845c408e 100644 (file)
--- 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 ecd1e09dbbf137d44996a4a83aec2c13b48d09f9..96e0efecefa6aa2f4bc97c098c08ee6c25f2e11c 100644 (file)
--- 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 5c5964962d0ca2f00157c4e533597a34b9a96979..bc68da38ea869ccf8100fd130b33f9d10f185255 100644 (file)
--- 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 81f253b6ff363e6fe1707a7ed0e2061ea69a25f9..f9333c9636076501fbc8df1806ee057dabddb4a5 100644 (file)
--- 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 22e90e56b5a9ff8d5f645b481fae8756e7246777..e7bfd55899a34ab8a314ecdfb9a98d8a55d0af15 100644 (file)
--- 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);