Re: [PATCH net-next 6/8] net: rps: change input_queue_tail_incr_save()

[kernel test robot <lkp@intel.com>]

Hi Eric,

kernel test robot noticed the following build errors:

[auto build test ERROR on net-next/main]

url:    https://github.com/intel-lab-lkp/linux/commits/Eric-Dumazet/net-move-kick_defer_list_purge-to-net-core-dev-h/20240329-011413
base:   net-next/main
patch link:    https://lore.kernel.org/r/20240328170309.2172584-7-edumazet%40google.com
patch subject: [PATCH net-next 6/8] net: rps: change input_queue_tail_incr_save()
config: sh-allmodconfig (https://download.01.org/0day-ci/archive/20240329/202403291901.lqImStGD-lkp@intel.com/config)
compiler: sh4-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240329/202403291901.lqImStGD-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202403291901.lqImStGD-lkp@intel.com/

All errors (new ones prefixed by >>):

   net/core/dev.c: In function 'enqueue_to_backlog':
>> net/core/dev.c:4819:24: error: implicit declaration of function 'rps_input_queue_tail_incr' [-Werror=implicit-function-declaration]
    4819 |                 tail = rps_input_queue_tail_incr(sd);
         |                        ^~~~~~~~~~~~~~~~~~~~~~~~~
>> net/core/dev.c:4823:17: error: implicit declaration of function 'rps_input_queue_tail_save' [-Werror=implicit-function-declaration]
    4823 |                 rps_input_queue_tail_save(qtail, tail);
         |                 ^~~~~~~~~~~~~~~~~~~~~~~~~
   net/core/dev.c: In function 'flush_backlog':
>> net/core/dev.c:5901:25: error: implicit declaration of function 'rps_input_queue_head_incr' [-Werror=implicit-function-declaration]
    5901 |                         rps_input_queue_head_incr(sd);
         |                         ^~~~~~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors


vim +/rps_input_queue_tail_incr +4819 net/core/dev.c

  4781	
  4782	/*
  4783	 * enqueue_to_backlog is called to queue an skb to a per CPU backlog
  4784	 * queue (may be a remote CPU queue).
  4785	 */
  4786	static int enqueue_to_backlog(struct sk_buff *skb, int cpu,
  4787				      unsigned int *qtail)
  4788	{
  4789		enum skb_drop_reason reason;
  4790		struct softnet_data *sd;
  4791		unsigned long flags;
  4792		unsigned int qlen;
  4793		int max_backlog;
  4794		u32 tail;
  4795	
  4796		reason = SKB_DROP_REASON_DEV_READY;
  4797		if (!netif_running(skb->dev))
  4798			goto bad_dev;
  4799	
  4800		reason = SKB_DROP_REASON_CPU_BACKLOG;
  4801		sd = &per_cpu(softnet_data, cpu);
  4802	
  4803		qlen = skb_queue_len_lockless(&sd->input_pkt_queue);
  4804		max_backlog = READ_ONCE(net_hotdata.max_backlog);
  4805		if (unlikely(qlen > max_backlog))
  4806			goto cpu_backlog_drop;
  4807		backlog_lock_irq_save(sd, &flags);
  4808		qlen = skb_queue_len(&sd->input_pkt_queue);
  4809		if (qlen <= max_backlog && !skb_flow_limit(skb, qlen)) {
  4810			if (!qlen) {
  4811				/* Schedule NAPI for backlog device. We can use
  4812				 * non atomic operation as we own the queue lock.
  4813				 */
  4814				if (!__test_and_set_bit(NAPI_STATE_SCHED,
  4815							&sd->backlog.state))
  4816					napi_schedule_rps(sd);
  4817			}
  4818			__skb_queue_tail(&sd->input_pkt_queue, skb);
> 4819			tail = rps_input_queue_tail_incr(sd);
  4820			backlog_unlock_irq_restore(sd, &flags);
  4821	
  4822			/* save the tail outside of the critical section */
> 4823			rps_input_queue_tail_save(qtail, tail);
  4824			return NET_RX_SUCCESS;
  4825		}
  4826	
  4827		backlog_unlock_irq_restore(sd, &flags);
  4828	
  4829	cpu_backlog_drop:
  4830		atomic_inc(&sd->dropped);
  4831	bad_dev:
  4832		dev_core_stats_rx_dropped_inc(skb->dev);
  4833		kfree_skb_reason(skb, reason);
  4834		return NET_RX_DROP;
  4835	}
  4836	

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