Hi Andrii,

I love your patch! Yet something to improve:

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

url:    https://github.com/0day-ci/linux/commits/Andrii-Nakryiko/BPF-perf-link-and-user-provided-context-value/20210726-014304
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: powerpc64-randconfig-s032-20210725 (attached as .config)
compiler: powerpc-linux-gcc (GCC) 10.3.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # apt-get install sparse
        # sparse version: v0.6.3-341-g8af24329-dirty
        # https://github.com/0day-ci/linux/commit/aebdacfee760371d78456f088ddcc6c5450ce5f5
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Andrii-Nakryiko/BPF-perf-link-and-user-provided-context-value/20210726-014304
        git checkout aebdacfee760371d78456f088ddcc6c5450ce5f5
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-10.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=powerpc64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   kernel/bpf/syscall.c: In function 'bpf_perf_link_release':
>> kernel/bpf/syscall.c:2919:2: error: implicit declaration of function 'perf_event_free_bpf_prog'; did you mean 'perf_event_detach_bpf_prog'? [-Werror=implicit-function-declaration]
    2919 |  perf_event_free_bpf_prog(event);
         |  ^~~~~~~~~~~~~~~~~~~~~~~~
         |  perf_event_detach_bpf_prog
   kernel/bpf/syscall.c: In function 'bpf_perf_link_attach':
>> kernel/bpf/syscall.c:2965:8: error: implicit declaration of function 'perf_event_set_bpf_prog'; did you mean 'perf_event_detach_bpf_prog'? [-Werror=implicit-function-declaration]
    2965 |  err = perf_event_set_bpf_prog(event, prog);
         |        ^~~~~~~~~~~~~~~~~~~~~~~
         |        perf_event_detach_bpf_prog
   cc1: some warnings being treated as errors


vim +2919 kernel/bpf/syscall.c

  2913	
  2914	static void bpf_perf_link_release(struct bpf_link *link)
  2915	{
  2916		struct bpf_perf_link *perf_link = container_of(link, struct bpf_perf_link, link);
  2917		struct perf_event *event = perf_link->perf_file->private_data;
  2918	
> 2919		perf_event_free_bpf_prog(event);
  2920		fput(perf_link->perf_file);
  2921	}
  2922	
  2923	static void bpf_perf_link_dealloc(struct bpf_link *link)
  2924	{
  2925		struct bpf_perf_link *perf_link = container_of(link, struct bpf_perf_link, link);
  2926	
  2927		kfree(perf_link);
  2928	}
  2929	
  2930	static const struct bpf_link_ops bpf_perf_link_lops = {
  2931		.release = bpf_perf_link_release,
  2932		.dealloc = bpf_perf_link_dealloc,
  2933	};
  2934	
  2935	static int bpf_perf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
  2936	{
  2937		struct bpf_link_primer link_primer;
  2938		struct bpf_perf_link *link;
  2939		struct perf_event *event;
  2940		struct file *perf_file;
  2941		int err;
  2942	
  2943		if (attr->link_create.flags)
  2944			return -EINVAL;
  2945	
  2946		perf_file = perf_event_get(attr->link_create.target_fd);
  2947		if (IS_ERR(perf_file))
  2948			return PTR_ERR(perf_file);
  2949	
  2950		link = kzalloc(sizeof(*link), GFP_USER);
  2951		if (!link) {
  2952			err = -ENOMEM;
  2953			goto out_put_file;
  2954		}
  2955		bpf_link_init(&link->link, BPF_LINK_TYPE_PERF_EVENT, &bpf_perf_link_lops, prog);
  2956		link->perf_file = perf_file;
  2957	
  2958		err = bpf_link_prime(&link->link, &link_primer);
  2959		if (err) {
  2960			kfree(link);
  2961			goto out_put_file;
  2962		}
  2963	
  2964		event = perf_file->private_data;
> 2965		err = perf_event_set_bpf_prog(event, prog);
  2966		if (err) {
  2967			bpf_link_cleanup(&link_primer);
  2968			goto out_put_file;
  2969		}
  2970		/* perf_event_set_bpf_prog() doesn't take its own refcnt on prog */
  2971		bpf_prog_inc(prog);
  2972	
  2973		return bpf_link_settle(&link_primer);
  2974	
  2975	out_put_file:
  2976		fput(perf_file);
  2977		return err;
  2978	}
  2979	

---
0-DAY CI Kernel Test Service, Intel Corporation
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