netdev - Re: [PATCH v2 net-next 0/3] gro: inline tcp6_gro

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Message-ID: <20260120073057.5ef3a5e1@kernel.org>
Date: Tue, 20 Jan 2026 07:30:57 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: Eric Dumazet <edumazet@...gle.com>
Cc: "David S . Miller" <davem@...emloft.net>, Paolo Abeni
 <pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
 netdev@...r.kernel.org, eric.dumazet@...il.com
Subject: Re: [PATCH v2 net-next 0/3] gro: inline tcp6_gro_{receive,complete}

On Sun, 18 Jan 2026 17:52:12 +0000 Eric Dumazet wrote:
> On some platforms, GRO stack is too deep and causes cpu stalls.
> 
> Decreasing call depths by one shows a 1.5 % gain on Zen2 cpus.
> (32 RX queues, 100Gbit NIC, RFS enabled, tcp_rr with 128 threads and 10,000 flows)
> 
> We can go further by inlining ipv6_gro_{receive,complete}
> and take care of IPv4 if there is interest.
> 
> Note: two temporary __always_inline will be replaced with
>       inline_for_performance when available.
> 
> v2: dealt with udp6_gro_receive()/udp6_gro_complete()
>     missing declarations (kernel test robot <lkp@...el.com>)
>     for CONFIG_MITIGATION_RETPOLINE=n

Still not good?

net/ipv6/udp_offload.c:136:17: error: static declaration of ‘udp6_gro_receive’ follows non-static declaration
  136 | struct sk_buff *udp6_gro_receive(struct list_head *head, struct sk_buff *skb)
      |                 ^~~~~~~~~~~~~~~~
In file included from net/ipv6/udp_offload.c:16:
./include/net/gro.h:408:17: note: previous declaration of ‘udp6_gro_receive’ with type ‘struct sk_buff *(struct list_head *, struct sk_buff *)’
  408 | struct sk_buff *udp6_gro_receive(struct list_head *, struct sk_buff *);
      |                 ^~~~~~~~~~~~~~~~
net/ipv6/udp_offload.c:168:29: error: static declaration of ‘udp6_gro_complete’ follows non-static declaration
  168 | INDIRECT_CALLABLE_SCOPE int udp6_gro_complete(struct sk_buff *skb, int nhoff)
      |                             ^~~~~~~~~~~~~~~~~
./include/net/gro.h:409:5: note: previous declaration of ‘udp6_gro_complete’ with type ‘int(struct sk_buff *, int)’
  409 | int udp6_gro_complete(struct sk_buff *, int);
      |     ^~~~~~~~~~~~~~~~~
-- 
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