Subject: Re: [PATCH bpf-next v2] net: Add a warning if NAPI cb missed xdp_do_flush().

From: kernel test robot <[email-masked]>
Date: Sat, 7 Oct 2023 01:21:41 +0800

Hi Sebastian,

kernel test robot noticed the following build warnings:

[auto build test WARNING on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Sebastian-Andrzej-Siewior/net-Add-a-warning-if-NAPI-cb-missed-xdp_do_flush/20231006-235117
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20231006154933.mQgxQHHt%40linutronix.de
patch subject: [PATCH bpf-next v2] net: Add a warning if NAPI cb missed xdp_do_flush().
config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20231007/[email-masked]/config)
compiler: m68k-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231007/[email-masked]/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 <[email-masked]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email-masked]/

All warnings (new ones prefixed by >>):

>> net/core/filter.c:4211:6: warning: no previous prototype for 'xdp_do_check_flushed' [-Wmissing-prototypes]
    4211 | void xdp_do_check_flushed(struct napi_struct *napi)
         |      ^~~~~~~~~~~~~~~~~~~~

vim +/xdp_do_check_flushed +4211 net/core/filter.c

  4209	
  4210	#if defined(CONFIG_DEBUG_NET) && defined(CONFIG_BPF_SYSCALL)
> 4211	void xdp_do_check_flushed(struct napi_struct *napi)
  4212	{
  4213		bool ret;
  4214	
  4215		ret = dev_check_flush();
  4216		ret |= cpu_map_check_flush();
  4217		ret |= xsk_map_check_flush();
  4218	
  4219		WARN_ONCE(ret, "Missing xdp_do_flush() invocation after NAPI by %ps\n",
  4220			  napi->poll);
  4221	}
  4222	#endif
  4223	

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