net: use indirect call wrappers at GRO transport layer

This avoids an indirect call in the receive path for TCP and UDP
packets. TCP takes precedence on UDP, so that we have a single
additional conditional in the common case.

When IPV6 is build as module, all gro symbols except UDPv6 are
builtin, while the latter belong to the ipv6 module, so we
need some special care.

v1 -> v2:
 - adapted to INDIRECT_CALL_ changes
v2 -> v3:
 - fix build issue with CONFIG_IPV6=m

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 35 insertions, 8 deletions

diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index ff8b484d2258..5c045691c302 100644
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -20,6 +20,23 @@
 
 #include "ip6_offload.h"
 
+/* All GRO functions are always builtin, except UDP over ipv6, which lays in
+ * ipv6 module, as it depends on UDPv6 lookup function, so we need special care
+ * when ipv6 is built as a module
+ */
+#if IS_BUILTIN(CONFIG_IPV6)
+#define INDIRECT_CALL_L4(f, f2, f1, ...) INDIRECT_CALL_2(f, f2, f1, __VA_ARGS__)
+#else
+#define INDIRECT_CALL_L4(f, f2, f1, ...) INDIRECT_CALL_1(f, f2, __VA_ARGS__)
+#endif
+
+#define indirect_call_gro_receive_l4(f2, f1, cb, head, skb)	\
+({								\
+	unlikely(gro_recursion_inc_test(skb)) ?			\
+		NAPI_GRO_CB(skb)->flush |= 1, NULL :		\
+		INDIRECT_CALL_L4(cb, f2, f1, head, skb);	\
+})
+
 static int ipv6_gso_pull_exthdrs(struct sk_buff *skb, int proto)
 {
 	const struct net_offload *ops = NULL;
@@ -164,6 +181,10 @@ static int ipv6_exthdrs_len(struct ipv6hdr *iph,
 	return len;
 }
 
+INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp6_gro_receive(struct list_head *,
+							   struct sk_buff *));
+INDIRECT_CALLABLE_DECLARE(struct sk_buff *udp6_gro_receive(struct list_head *,
+							   struct sk_buff *));
 INDIRECT_CALLABLE_SCOPE struct sk_buff *ipv6_gro_receive(struct list_head *head,
 							 struct sk_buff *skb)
 {
@@ -260,7 +281,8 @@ not_same_flow:
 
 	skb_gro_postpull_rcsum(skb, iph, nlen);
 
-	pp = call_gro_receive(ops->callbacks.gro_receive, head, skb);
+	pp = indirect_call_gro_receive_l4(tcp6_gro_receive, udp6_gro_receive,
+					 ops->callbacks.gro_receive, head, skb);
 
 out_unlock:
 	rcu_read_unlock();
@@ -301,6 +323,8 @@ static struct sk_buff *ip4ip6_gro_receive(struct list_head *head,
 	return inet_gro_receive(head, skb);
 }
 
+INDIRECT_CALLABLE_DECLARE(int tcp6_gro_complete(struct sk_buff *, int));
+INDIRECT_CALLABLE_DECLARE(int udp6_gro_complete(struct sk_buff *, int));
 INDIRECT_CALLABLE_SCOPE int ipv6_gro_complete(struct sk_buff *skb, int nhoff)
 {
 	const struct net_offload *ops;
@@ -320,7 +344,8 @@ INDIRECT_CALLABLE_SCOPE int ipv6_gro_complete(struct sk_buff *skb, int nhoff)
 	if (WARN_ON(!ops || !ops->callbacks.gro_complete))
 		goto out_unlock;
 
-	err = ops->callbacks.gro_complete(skb, nhoff);
+	err = INDIRECT_CALL_L4(ops->callbacks.gro_complete, tcp6_gro_complete,
+			       udp6_gro_complete, skb, nhoff);
 
 out_unlock:
 	rcu_read_unlock();
diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c
index e72947c99454..3179c425d7ff 100644
--- a/net/ipv6/tcpv6_offload.c
+++ b/net/ipv6/tcpv6_offload.c
@@ -9,14 +9,15 @@
  *
  *      TCPv6 GSO/GRO support
  */
+#include <linux/indirect_call_wrapper.h>
 #include <linux/skbuff.h>
 #include <net/protocol.h>
 #include <net/tcp.h>
 #include <net/ip6_checksum.h>
 #include "ip6_offload.h"
 
-static struct sk_buff *tcp6_gro_receive(struct list_head *head,
-					struct sk_buff *skb)
+INDIRECT_CALLABLE_SCOPE
+struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb)
 {
 	/* Don't bother verifying checksum if we're going to flush anyway. */
 	if (!NAPI_GRO_CB(skb)->flush &&
@@ -29,7 +30,7 @@ static struct sk_buff *tcp6_gro_receive(struct list_head *head,
 	return tcp_gro_receive(head, skb);
 }
 
-static int tcp6_gro_complete(struct sk_buff *skb, int thoff)
+INDIRECT_CALLABLE_SCOPE int tcp6_gro_complete(struct sk_buff *skb, int thoff)
 {
 	const struct ipv6hdr *iph = ipv6_hdr(skb);
 	struct tcphdr *th = tcp_hdr(skb);
diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
index 828b2457f97b..83b11d0ac091 100644
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c
@@ -11,6 +11,7 @@
  */
 #include <linux/skbuff.h>
 #include <linux/netdevice.h>
+#include <linux/indirect_call_wrapper.h>
 #include <net/protocol.h>
 #include <net/ipv6.h>
 #include <net/udp.h>
@@ -114,8 +115,8 @@ out:
 	return segs;
 }
 
-static struct sk_buff *udp6_gro_receive(struct list_head *head,
-					struct sk_buff *skb)
+INDIRECT_CALLABLE_SCOPE
+struct sk_buff *udp6_gro_receive(struct list_head *head, struct sk_buff *skb)
 {
 	struct udphdr *uh = udp_gro_udphdr(skb);
 
@@ -142,7 +143,7 @@ flush:
 	return NULL;
 }
 
-static int udp6_gro_complete(struct sk_buff *skb, int nhoff)
+INDIRECT_CALLABLE_SCOPE int udp6_gro_complete(struct sk_buff *skb, int nhoff)
 {
 	const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);