Hi Andrii,

[FYI, it's a private test report for your RFC patch.]
[auto build test WARNING on bpf-next/master]

url:    https://github.com/0day-ci/linux/commits/Andrii-Nakryiko/Support-kernel-module-ksym-variables/20201211-123414
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: i386-randconfig-r036-20201209 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/6612e8dbf119471e023d79a56d7834fceeb3e33b
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Andrii-Nakryiko/Support-kernel-module-ksym-variables/20201211-123414
        git checkout 6612e8dbf119471e023d79a56d7834fceeb3e33b
        # save the attached .config to linux build tree
        make W=1 ARCH=i386 

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

All warnings (new ones prefixed by >>):

   kernel/bpf/core.c:1350:12: warning: no previous prototype for 'bpf_probe_read_kernel' [-Wmissing-prototypes]
    1350 | u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr)
         |            ^~~~~~~~~~~~~~~~~~~~~
   In file included from kernel/bpf/core.c:21:
   kernel/bpf/core.c: In function '___bpf_prog_run':
   include/linux/filter.h:888:3: warning: cast between incompatible function types from 'u64 (*)(u64,  u64,  u64,  u64,  u64)' {aka 'long long unsigned int (*)(long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int)'} to 'u64 (*)(u64,  u64,  u64,  u64,  u64,  const struct bpf_insn *)' {aka 'long long unsigned int (*)(long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int,  const struct bpf_insn *)'} [-Wcast-function-type]
     888 |  ((u64 (*)(u64, u64, u64, u64, u64, const struct bpf_insn *)) \
         |   ^
   kernel/bpf/core.c:1518:13: note: in expansion of macro '__bpf_call_base_args'
    1518 |   BPF_R0 = (__bpf_call_base_args + insn->imm)(BPF_R1, BPF_R2,
         |             ^~~~~~~~~~~~~~~~~~~~
   kernel/bpf/core.c: At top level:
   kernel/bpf/core.c:1704:6: warning: no previous prototype for 'bpf_patch_call_args' [-Wmissing-prototypes]
    1704 | void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth)
         |      ^~~~~~~~~~~~~~~~~~~
   In file included from kernel/bpf/core.c:21:
   kernel/bpf/core.c: In function 'bpf_patch_call_args':
   include/linux/filter.h:888:3: warning: cast between incompatible function types from 'u64 (*)(u64,  u64,  u64,  u64,  u64)' {aka 'long long unsigned int (*)(long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int)'} to 'u64 (*)(u64,  u64,  u64,  u64,  u64,  const struct bpf_insn *)' {aka 'long long unsigned int (*)(long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int,  long long unsigned int,  const struct bpf_insn *)'} [-Wcast-function-type]
     888 |  ((u64 (*)(u64, u64, u64, u64, u64, const struct bpf_insn *)) \
         |   ^
   kernel/bpf/core.c:1709:3: note: in expansion of macro '__bpf_call_base_args'
    1709 |   __bpf_call_base_args;
         |   ^~~~~~~~~~~~~~~~~~~~
   kernel/bpf/core.c: At top level:
   kernel/bpf/core.c:2102:6: warning: no previous prototype for '__bpf_free_used_maps' [-Wmissing-prototypes]
    2102 | void __bpf_free_used_maps(struct bpf_prog_aux *aux,
         |      ^~~~~~~~~~~~~~~~~~~~
>> kernel/bpf/core.c:2122:6: warning: no previous prototype for '__bpf_free_used_btfs' [-Wmissing-prototypes]
    2122 | void __bpf_free_used_btfs(struct bpf_prog_aux *aux,
         |      ^~~~~~~~~~~~~~~~~~~~

vim +/__bpf_free_used_btfs +2122 kernel/bpf/core.c

  2121	
> 2122	void __bpf_free_used_btfs(struct bpf_prog_aux *aux,
  2123				  struct btf_mod_pair *used_btfs, u32 len)
  2124	{
  2125	#ifdef CONFIG_BPF_SYSCALL
  2126		struct btf_mod_pair *btf_mod;
  2127		u32 i;
  2128	
  2129		for (i = 0; i < len; i++) {
  2130			btf_mod = &used_btfs[i];
  2131			if (btf_mod->module)
  2132				module_put(btf_mod->module);
  2133			btf_put(btf_mod->btf);
  2134		}
  2135	#endif
  2136	}
  2137	

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