Re: [PATCH v4 perf, bpf-next 3/7] perf, bpf: introduce PERF_RECORD_BPF_EVENT

Hi Song,

Thank you for the patch! Yet something to improve:

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

url:    https://github.com/0day-ci/linux/commits/Song-Liu/perf-bpf-Introduce-PERF_RECORD_KSYMBOL/20181220-023635
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: nds32-allmodconfig (attached as .config)
compiler: nds32le-linux-gcc (GCC) 6.4.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=6.4.0 make.cross ARCH=nds32 

All errors (new ones prefixed by >>):

   kernel/bpf/syscall.c: In function '__bpf_prog_put':

quoted

kernel/bpf/syscall.c:1214:3: error: implicit declaration of function 'perf_event_bpf_event' [-Werror=implicit-function-declaration]

      perf_event_bpf_event(prog, PERF_BPF_EVENT_PROG_UNLOAD, 0);
      ^~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors

vim +/perf_event_bpf_event +1214 kernel/bpf/syscall.c

  1210	
  1211	static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock)
  1212	{
  1213		if (atomic_dec_and_test(&prog->aux->refcnt)) {

1214			perf_event_bpf_event(prog, PERF_BPF_EVENT_PROG_UNLOAD, 0);

  1215			/* bpf_prog_free_id() must be called first */
  1216			bpf_prog_free_id(prog, do_idr_lock);
  1217			bpf_prog_kallsyms_del_all(prog);
  1218			btf_put(prog->aux->btf);
  1219			kvfree(prog->aux->func_info);
  1220			bpf_prog_free_linfo(prog);
  1221	
  1222			call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu);
  1223		}
  1224	}
  1225	

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