netdev - Re: [PATCH v2 net-next 3/3] tcp: add one skb cache for rx

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Date:   Fri, 22 Mar 2019 08:20:00 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     kbuild test robot <lkp@...el.com>,
        Eric Dumazet <edumazet@...gle.com>
Cc:     kbuild-all@...org, "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Soheil Hassas Yeganeh <soheil@...gle.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Florian Westphal <fw@...len.de>,
        Tom Herbert <tom@...bertland.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH v2 net-next 3/3] tcp: add one skb cache for rx



On 03/22/2019 08:00 AM, kbuild test robot wrote:
> Hi Eric,
> 
> I love your patch! Yet something to improve:
> 
> [auto build test ERROR on net-next/master]
> 
> url:    https://github.com/0day-ci/linux/commits/Eric-Dumazet/tcp-add-rx-tx-cache-to-reduce-lock-contention/20190322-215506
> config: x86_64-randconfig-x016-201911 (attached as .config)
> compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
> reproduce:
>         # save the attached .config to linux build tree
>         make ARCH=x86_64 
> 
> All errors (new ones prefixed by >>):
> 
>    In file included from include/linux/dynamic_debug.h:6:0,
>                     from include/linux/printk.h:330,
>                     from include/linux/kernel.h:15,
>                     from include/linux/list.h:9,
>                     from include/linux/module.h:9,
>                     from drivers//net/ethernet/intel/e1000/e1000.h:10,
>                     from drivers//net/ethernet/intel/e1000/e1000_main.c:4:
>    include/net/sock.h: In function 'sk_eat_skb':
>>> include/net/sock.h:2442:31: error: 'rps_needed' undeclared (first use in this function); did you mean 'free_netdev'?
>      if (!static_branch_unlikely(&rps_needed) && !sk->sk_rx_skb_cache) {
>                                   ^
>    include/linux/jump_label.h:466:43: note: in definition of macro 'static_branch_unlikely'
>      if (__builtin_types_compatible_p(typeof(*x), struct static_key_true)) \
>                                               ^
>    include/net/sock.h:2442:31: note: each undeclared identifier is reported only once for each function it appears in
>      if (!static_branch_unlikely(&rps_needed) && !sk->sk_rx_skb_cache) {
>                                   ^
>    include/linux/jump_label.h:466:43: note: in definition of macro 'static_branch_unlikely'
>      if (__builtin_types_compatible_p(typeof(*x), struct static_key_true)) \
>                                               ^
> 
> vim +2442 include/net/sock.h
> 
>   2430	
>   2431	/**
>   2432	 * sk_eat_skb - Release a skb if it is no longer needed
>   2433	 * @sk: socket to eat this skb from
>   2434	 * @skb: socket buffer to eat
>   2435	 *
>   2436	 * This routine must be called with interrupts disabled or with the socket
>   2437	 * locked so that the sk_buff queue operation is ok.
>   2438	*/
>   2439	static inline void sk_eat_skb(struct sock *sk, struct sk_buff *skb)
>   2440	{
>   2441		__skb_unlink(skb, &sk->sk_receive_queue);

I guess all this makes sense on SMP systems only :)

>> 2442		if (!static_branch_unlikely(&rps_needed) && !sk->sk_rx_skb_cache) {
>   2443			sk->sk_rx_skb_cache = skb;
>   2444			skb_orphan(skb);
>   2445			return;
>   2446		}
>   2447		__kfree_skb(skb);
>   2448	}
>   2449	
> 
> ---
> 0-DAY kernel test infrastructure                Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
>