Re: [PATCH bpf 2/3] net: fix usage of multi-buffer BPF helper for ZC AF_XDP

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

Hi Maciej,

kernel test robot noticed the following build warnings:

[auto build test WARNING on bpf/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Maciej-Fijalkowski/xsk-recycle-buffer-in-case-Rx-queue-was-full/20231208-193306
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git master
patch link:    https://lore.kernel.org/r/20231208112945.313687-3-maciej.fijalkowski%40intel.com
patch subject: [PATCH bpf 2/3] net: fix usage of multi-buffer BPF helper for ZC AF_XDP
config: i386-randconfig-013-20231208 (https://download.01.org/0day-ci/archive/20231209/202312090126.Zap0AFox-lkp@intel.com/config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231209/202312090126.Zap0AFox-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/202312090126.Zap0AFox-lkp@intel.com/

All warnings (new ones prefixed by >>):

   net/core/filter.c: In function '__shrink_data':
   net/core/filter.c:4102:3: error: implicit declaration of function 'xsk_buff_get_tail'; did you mean 'xsk_buff_get_frag'? [-Werror=implicit-function-declaration]
      xsk_buff_get_tail(xdp)->data_end -= shrink;
      ^~~~~~~~~~~~~~~~~
      xsk_buff_get_frag
   net/core/filter.c:4102:25: error: invalid type argument of '->' (have 'int')
      xsk_buff_get_tail(xdp)->data_end -= shrink;
                            ^~
   net/core/filter.c: In function 'shrink_data':
>> net/core/filter.c:4115:12: warning: assignment makes pointer from integer without a cast [-Wint-conversion]
       zc_frag = xsk_buff_get_tail(xdp);
               ^
   net/core/filter.c:4117:4: error: implicit declaration of function 'xsk_buff_tail_del'; did you mean 'xsk_buff_alloc'? [-Werror=implicit-function-declaration]
       xsk_buff_tail_del(zc_frag);
       ^~~~~~~~~~~~~~~~~
       xsk_buff_alloc
   cc1: some warnings being treated as errors


vim +4115 net/core/filter.c

  4105	
  4106	static bool shrink_data(struct xdp_buff *xdp, skb_frag_t *frag, int shrink)
  4107	{
  4108		struct xdp_mem_info *mem_info = &xdp->rxq->mem;
  4109	
  4110		if (skb_frag_size(frag) == shrink) {
  4111			struct page *page = skb_frag_page(frag);
  4112			struct xdp_buff *zc_frag = NULL;
  4113	
  4114			if (mem_info->type == MEM_TYPE_XSK_BUFF_POOL) {
> 4115				zc_frag = xsk_buff_get_tail(xdp);
  4116				xdp_buff_clear_frags_flag(zc_frag);
  4117				xsk_buff_tail_del(zc_frag);
  4118			}
  4119	
  4120			__xdp_return(page_address(page), mem_info, false, zc_frag);
  4121			return true;
  4122		}
  4123		__shrink_data(xdp, mem_info, frag, shrink);
  4124		return false;
  4125	}
  4126	

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