[PATCH net v1 1/2] net: gro: add flush check in udp_gro_receive_segment

[Richard Gobert <richardbgobert@gmail.com>]

GRO-GSO path is supposed to be transparent and as such L3 flush checks are
relevant to all flows which call skb_gro_receive. This patch uses the same
logic and code from tcp_gro_receive but in the relevant flow path in
udp_gro_receive_segment.

Fixes: 36707061d6ba ("udp: allow forwarding of plain (non-fraglisted) UDP GRO packets")
Signed-off-by: Richard Gobert <richardbgobert@gmail.com>
---
 net/ipv4/udp_offload.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 3498dd1d0694..1f4e08f43c4b 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -471,6 +471,7 @@ static struct sk_buff *udp_gro_receive_segment(struct list_head *head,
 	struct sk_buff *p;
 	unsigned int ulen;
 	int ret = 0;
+	int flush;
 
 	/* requires non zero csum, for symmetry with GSO */
 	if (!uh->check) {
@@ -528,7 +529,17 @@ static struct sk_buff *udp_gro_receive_segment(struct list_head *head,
 				skb_gro_postpull_rcsum(skb, uh,
 						       sizeof(struct udphdr));
 
-				ret = skb_gro_receive(p, skb);
+				flush = NAPI_GRO_CB(p)->flush;
+
+				if (NAPI_GRO_CB(p)->flush_id != 1 ||
+				    NAPI_GRO_CB(p)->count != 1 ||
+				    !NAPI_GRO_CB(p)->is_atomic)
+					flush |= NAPI_GRO_CB(p)->flush_id;
+				else
+					NAPI_GRO_CB(p)->is_atomic = false;
+
+				if (flush || skb_gro_receive(p, skb))
+					ret = 1;
 			}
 		}
 
-- 
2.36.1