net: gre: move GSO functions to gre_offload

Similarly to TCP/UDP offloading, move all related GRE functions to
gre_offload.c to make things more explicit and similar to the rest
of the code.

Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 135 insertions, 103 deletions

diff --git a/include/net/gre.h b/include/net/gre.h
index a5a4ddf05300..57e4afdf7879 100644
--- a/include/net/gre.h
+++ b/include/net/gre.h
@@ -32,6 +32,10 @@ struct gre_cisco_protocol {
 
 int gre_cisco_register(struct gre_cisco_protocol *proto);
 int gre_cisco_unregister(struct gre_cisco_protocol *proto);
+
+int gre_offload_init(void);
+void gre_offload_exit(void);
+
 void gre_build_header(struct sk_buff *skb, const struct tnl_ptk_info *tpi,
                       int hdr_len);
 struct sk_buff *gre_handle_offloads(struct sk_buff *skb, bool gre_csum);
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index 86ded0bac9c7..4b81e91c80fe 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_PROC_FS) += proc.o
 obj-$(CONFIG_IP_MULTIPLE_TABLES) += fib_rules.o
 obj-$(CONFIG_IP_MROUTE) += ipmr.o
 obj-$(CONFIG_NET_IPIP) += ipip.o
+gre-y := gre_demux.o gre_offload.o
 obj-$(CONFIG_NET_IPGRE_DEMUX) += gre.o
 obj-$(CONFIG_NET_IPGRE) += ip_gre.o
 obj-$(CONFIG_NET_IPVTI) += ip_vti.o
diff --git a/net/ipv4/gre.c b/net/ipv4/gre_demux.c
index ba4803e609b5..736c9fc3ef93 100644
--- a/net/ipv4/gre.c
+++ b/net/ipv4/gre_demux.c
@@ -334,113 +334,12 @@ static void gre_err(struct sk_buff *skb, u32 info)
         rcu_read_unlock();
 }
 
-static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
-                                       netdev_features_t features)
-{
-        struct sk_buff *segs = ERR_PTR(-EINVAL);
-        netdev_features_t enc_features;
-        int ghl = GRE_HEADER_SECTION;
-        struct gre_base_hdr *greh;
-        int mac_len = skb->mac_len;
-        __be16 protocol = skb->protocol;
-        int tnl_hlen;
-        bool csum;
-
-        if (unlikely(skb_shinfo(skb)->gso_type &
-                                ~(SKB_GSO_TCPV4 |
-                                  SKB_GSO_TCPV6 |
-                                  SKB_GSO_UDP |
-                                  SKB_GSO_DODGY |
-                                  SKB_GSO_TCP_ECN |
-                                  SKB_GSO_GRE)))
-                goto out;
-
-        if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
-                goto out;
-
-        greh = (struct gre_base_hdr *)skb_transport_header(skb);
-
-        if (greh->flags & GRE_KEY)
-                ghl += GRE_HEADER_SECTION;
-        if (greh->flags & GRE_SEQ)
-                ghl += GRE_HEADER_SECTION;
-        if (greh->flags & GRE_CSUM) {
-                ghl += GRE_HEADER_SECTION;
-                csum = true;
-        } else
-                csum = false;
-
-        /* setup inner skb. */
-        skb->protocol = greh->protocol;
-        skb->encapsulation = 0;
-
-        if (unlikely(!pskb_may_pull(skb, ghl)))
-                goto out;
-        __skb_pull(skb, ghl);
-        skb_reset_mac_header(skb);
-        skb_set_network_header(skb, skb_inner_network_offset(skb));
-        skb->mac_len = skb_inner_network_offset(skb);
-
-        /* segment inner packet. */
-        enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
-        segs = skb_mac_gso_segment(skb, enc_features);
-        if (!segs || IS_ERR(segs))
-                goto out;
-
-        skb = segs;
-        tnl_hlen = skb_tnl_header_len(skb);
-        do {
-                __skb_push(skb, ghl);
-                if (csum) {
-                        __be32 *pcsum;
-
-                        if (skb_has_shared_frag(skb)) {
-                                int err;
-
-                                err = __skb_linearize(skb);
-                                if (err) {
-                                        kfree_skb(segs);
-                                        segs = ERR_PTR(err);
-                                        goto out;
-                                }
-                        }
-
-                        greh = (struct gre_base_hdr *)(skb->data);
-                        pcsum = (__be32 *)(greh + 1);
-                        *pcsum = 0;
-                        *(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
-                }
-                __skb_push(skb, tnl_hlen - ghl);
-
-                skb_reset_mac_header(skb);
-                skb_set_network_header(skb, mac_len);
-                skb->mac_len = mac_len;
-                skb->protocol = protocol;
-        } while ((skb = skb->next));
-out:
-        return segs;
-}
-
-static int gre_gso_send_check(struct sk_buff *skb)
-{
-        if (!skb->encapsulation)
-                return -EINVAL;
-        return 0;
-}
-
 static const struct net_protocol net_gre_protocol = {
         .handler     = gre_rcv,
         .err_handler = gre_err,
         .netns_ok    = 1,
 };
 
-static const struct net_offload gre_offload = {
-        .callbacks = {
-                .gso_send_check =       gre_gso_send_check,
-                .gso_segment    =       gre_gso_segment,
-        },
-};
-
 static const struct gre_protocol ipgre_protocol = {
         .handler     = gre_cisco_rcv,
         .err_handler = gre_cisco_err,
@@ -485,7 +384,7 @@ static int __init gre_init(void)
                 goto err_gre;
         }
 
-        if (inet_add_offload(&gre_offload, IPPROTO_GRE)) {
+        if (gre_offload_init()) {
                 pr_err("can't add protocol offload\n");
                 goto err_gso;
         }
@@ -501,7 +400,8 @@ err:
 
 static void __exit gre_exit(void)
 {
-        inet_del_offload(&gre_offload, IPPROTO_GRE);
+        gre_offload_exit();
+
         gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO);
         inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
 }
diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
new file mode 100644
index 000000000000..a9d8cd2bff4b
--- /dev/null
+++ b/net/ipv4/gre_offload.c
@@ -0,0 +1,127 @@
+/*
+ *      IPV4 GSO/GRO offload support
+ *      Linux INET implementation
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ *
+ *      GRE GSO support
+ */
+
+#include <linux/skbuff.h>
+#include <net/protocol.h>
+#include <net/gre.h>
+
+static int gre_gso_send_check(struct sk_buff *skb)
+{
+        if (!skb->encapsulation)
+                return -EINVAL;
+        return 0;
+}
+
+static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
+                                       netdev_features_t features)
+{
+        struct sk_buff *segs = ERR_PTR(-EINVAL);
+        netdev_features_t enc_features;
+        int ghl = GRE_HEADER_SECTION;
+        struct gre_base_hdr *greh;
+        int mac_len = skb->mac_len;
+        __be16 protocol = skb->protocol;
+        int tnl_hlen;
+        bool csum;
+
+        if (unlikely(skb_shinfo(skb)->gso_type &
+                                ~(SKB_GSO_TCPV4 |
+                                  SKB_GSO_TCPV6 |
+                                  SKB_GSO_UDP |
+                                  SKB_GSO_DODGY |