Re: [PATCH net-next 0/2] udp_tunnel: GRO optimizations

[Jakub Kicinski <kuba@kernel.org>]

On Thu,  6 Mar 2025 16:56:51 +0100 Paolo Abeni wrote:
> The UDP tunnel GRO stage is source of measurable overhead for workload
> based on UDP-encapsulated traffic: each incoming packets requires a full
> UDP socket lookup and an indirect call.
> 
> In the most common setups a single UDP tunnel device is used. In such
> case we can optimize both the lookup and the indirect call.
> 
> Patch 1 tracks per netns the active UDP tunnels and replaces the socket
> lookup with a single destination port comparison when possible.
> 
> Patch 2 tracks the different types of UDP tunnels and replaces the
> indirect call with a static one when there is a single UDP tunnel type
> active.
> 
> I measure ~5% performance improvement in TCP over UDP tunnel stream
> tests on top of this series.

Breaks the build with NET_UDP_TUNNEL=n (in contest) :(

net/ipv4/udp_offload.c: In function ‘udp_tunnel_gro_rcv’:
net/ipv4/udp_offload.c:172:16: error: returning ‘struct sk_buff *’ from a function with incompatible return type ‘struct skbuff *’ [-Werror=incompatible-pointer-types]
  172 |         return call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb);
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
net/ipv4/udp_offload.c: In function ‘udp_gro_receive’:
net/ipv4/udp_offload.c:786:12: error: assignment to ‘struct sk_buff *’ from incompatible pointer type ‘struct skbuff *’ [-Werror=incompatible-pointer-types]
  786 |         pp = udp_tunnel_gro_rcv(sk, head, skb);
      |            ^
In file included from ./include/linux/seqlock.h:19,
                 from ./include/linux/dcache.h:11,
                 from ./include/linux/fs.h:8,
                 from ./include/linux/highmem.h:5,
                 from ./include/linux/bvec.h:10,
                 from ./include/linux/skbuff.h:17,
                 from net/ipv4/udp_offload.c:9:
net/ipv4/udp_offload.c: In function ‘udpv4_offload_init’:
net/ipv4/udp_offload.c:936:21: error: ‘udp_tunnel_gro_type_lock’ undeclared (first use in this function); did you mean ‘udp_tunnel_gro_rcv’?
  936 |         mutex_init(&udp_tunnel_gro_type_lock);
      |                     ^~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/mutex.h:64:23: note: in definition of macro ‘mutex_init’
   64 |         __mutex_init((mutex), #mutex, &__key);                          \
      |                       ^~~~~
net/ipv4/udp_offload.c:936:21: note: each undeclared identifier is reported only once for each function it appears in
  936 |         mutex_init(&udp_tunnel_gro_type_lock);
      |                     ^~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/mutex.h:64:23: note: in definition of macro ‘mutex_init’
   64 |         __mutex_init((mutex), #mutex, &__key);                          \
      |                       ^~~~~
cc1: all warnings being treated as errors
-- 
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