linux-kernel - [ast-bpf:ptr 1/1] kernel/bpf/helpers.c:1395:36: warning: unused variable 'bpf_kptr_get

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Message-ID: <202202161630.kf6vptKz-lkp@intel.com>
Date:   Wed, 16 Feb 2022 16:25:14 +0800
From:   kernel test robot <lkp@...el.com>
To:     Alexei Starovoitov <ast@...nel.org>
Cc:     llvm@...ts.linux.dev, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org
Subject: [ast-bpf:ptr 1/1] kernel/bpf/helpers.c:1395:36: warning: unused
 variable 'bpf_kptr_get_proto'

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/ast/bpf.git ptr
head:   c49309ef3e137c753d1a87de044f007655fb9958
commit: c49309ef3e137c753d1a87de044f007655fb9958 [1/1] bpf: kptr
config: hexagon-randconfig-r001-20220216 (https://download.01.org/0day-ci/archive/20220216/202202161630.kf6vptKz-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 0e628a783b935c70c80815db6c061ec84f884af5)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://git.kernel.org/pub/scm/linux/kernel/git/ast/bpf.git/commit/?id=c49309ef3e137c753d1a87de044f007655fb9958
        git remote add ast-bpf https://git.kernel.org/pub/scm/linux/kernel/git/ast/bpf.git
        git fetch --no-tags ast-bpf ptr
        git checkout c49309ef3e137c753d1a87de044f007655fb9958
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash kernel/bpf/

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

All warnings (new ones prefixed by >>):

>> kernel/bpf/helpers.c:1395:36: warning: unused variable 'bpf_kptr_get_proto' [-Wunused-const-variable]
   static const struct bpf_func_proto bpf_kptr_get_proto = {
                                      ^
>> kernel/bpf/helpers.c:1411:36: warning: unused variable 'bpf_kptr_xchg_proto' [-Wunused-const-variable]
   static const struct bpf_func_proto bpf_kptr_xchg_proto = {
                                      ^
>> kernel/bpf/helpers.c:1433:36: warning: unused variable 'bpf_kptr_try_set_proto' [-Wunused-const-variable]
   static const struct bpf_func_proto bpf_kptr_try_set_proto = {
                                      ^
   3 warnings generated.


vim +/bpf_kptr_get_proto +1395 kernel/bpf/helpers.c

  1394	
> 1395	static const struct bpf_func_proto bpf_kptr_get_proto = {
  1396		.func		= bpf_kptr_get,
  1397		.gpl_only	= false,
  1398		.ret_type	= RET_PTR_TO_BTF_ID_OR_NULL,
  1399		.arg1_type	= ARG_PTR_TO_MAP_VALUE,
  1400	};
  1401	
  1402	BPF_CALL_2(bpf_kptr_xchg, void **, kptr, void *, ptr)
  1403	{
  1404		/* ptr is ptr_to_btf_id returned from bpf_*_lookup() with ptr->refcnt >= 1
  1405		 * or ptr == NULL.
  1406		 * returns ptr_to_btf_id with refcnt >= 1 or NULL
  1407		 */
  1408		return (long) xchg(kptr, ptr);
  1409	}
  1410	
> 1411	static const struct bpf_func_proto bpf_kptr_xchg_proto = {
  1412		.func		= bpf_kptr_xchg,
  1413		.gpl_only	= false,
  1414		.ret_type	= RET_PTR_TO_BTF_ID_OR_NULL,
  1415		.arg1_type	= ARG_PTR_TO_MAP_VALUE,
  1416	};
  1417	
  1418	BPF_CALL_3(bpf_kptr_try_set, void **, kptr, void *, ptr, int, refcnt_off)
  1419	{
  1420		/* ptr is ptr_to_btf_id returned from bpf_*_lookup() with ptr->refcnt >= 1
  1421		 * refcount_inc() has to be done before cmpxchg() because
  1422		 * another cpu might do bpf_kptr_xchg+release.
  1423		 */
  1424		refcount_inc((refcount_t *)(ptr + refcnt_off));
  1425		if (cmpxchg(kptr, NULL, ptr)) {
  1426			/* refcnt >= 2 here */
  1427			refcount_dec((refcount_t *)(ptr + refcnt_off));
  1428			return -EBUSY;
  1429		}
  1430		return 0;
  1431	}
  1432	
> 1433	static const struct bpf_func_proto bpf_kptr_try_set_proto = {
  1434		.func		= bpf_kptr_try_set,
  1435		.gpl_only	= false,
  1436		.ret_type	= RET_INTEGER,
  1437		.arg1_type	= ARG_PTR_TO_MAP_VALUE,
  1438		.arg2_type	= ARG_PTR_TO_BTF_ID,
  1439	};
  1440	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org