When UDP GRO is enabled, the UDP_GRO cmsg will carry the ingress
datagram size. User-space can use such info to compute the original
packets layout.
Signed-off-by: Paolo Abeni <pab...@redhat.com>
---
Note: I avoided setting a bit in cmsg_flag for UDP_GRO, as that
attempt produced some uglyfication, expecially on the ipv6 side
with no measurable performances benefits.
---
include/linux/udp.h | 11 +++++++++++
net/ipv4/udp.c | 4 ++++
net/ipv6/udp.c | 3 +++
3 files changed, 18 insertions(+)
diff --git a/include/linux/udp.h b/include/linux/udp.h
index f613b329852e..e23d5024f42f 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -121,6 +121,17 @@ static inline bool udp_get_no_check6_rx(struct sock *sk)
return udp_sk(sk)->no_check6_rx;
}
+static inline void udp_cmsg_recv(struct msghdr *msg, struct sock *sk,
+ struct sk_buff *skb)
+{
+ int gso_size;
+
+ if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) {
+ gso_size = skb_shinfo(skb)->gso_size;
+ put_cmsg(msg, SOL_UDP, UDP_GRO, sizeof(gso_size), &gso_size);
+ }
+}
+
#define udp_portaddr_for_each_entry(__sk, list) \
hlist_for_each_entry(__sk, list, __sk_common.skc_portaddr_node)
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 4d4f4d044c28..b345f71b1cbb 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1714,6 +1714,10 @@ int udp_recvmsg(struct sock *sk, struct msghdr *msg,
size_t len, int noblock,
memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
*addr_len = sizeof(*sin);
}
+
+ if (udp_sk(sk)->gro_enabled)
+ udp_cmsg_recv(msg, sk, skb);
+
if (inet->cmsg_flags)
ip_cmsg_recv_offset(msg, sk, skb, sizeof(struct udphdr), off);
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index fc0ce6c59ebb..8e76e719305c 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -421,6 +421,9 @@ int udpv6_recvmsg(struct sock *sk, struct msghdr *msg,
size_t len,
*addr_len = sizeof(*sin6);
}
+ if (udp_sk(sk)->gro_enabled)
+ udp_cmsg_recv(msg, sk, skb);
+
if (np->rxopt.all)
ip6_datagram_recv_common_ctl(sk, msg, skb);
--
2.17.2
