udp: use skb_attempt_defer_free()

Move skb freeing from udp recvmsg() path to the cpu
which allocated/received it, as TCP did in linux-5.17.

This increases max thoughput by 20% to 30%, depending
on number of BH producers.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250916160951.541279-11-edumazet@google.com
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 7d1444821ee51a19cd5fd0dd5b8d096104c9283c..0c40426628eb2306b609881341a51307c4993871 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1825,6 +1825,13 @@ void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len)
        if (unlikely(READ_ONCE(udp_sk(sk)->peeking_with_offset)))
                sk_peek_offset_bwd(sk, len);
 
+       if (!skb_shared(skb)) {
+               if (unlikely(udp_skb_has_head_state(skb)))
+                       skb_release_head_state(skb);
+               skb_attempt_defer_free(skb);
+               return;
+       }
+
        if (!skb_unref(skb))
                return;