[ast-bpf:relo_core 5/11] kernel/bpf/btf.c:6524:2: warning: Value stored to 'err' is never read [clang-analyzer-deadcode.DeadStores]

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/ast/bpf.git relo_core
head:   35a0182c26565e1db43f99a764834bff8a2e4202
commit: 98beca424883749fbcf9f244bb26c96ed3102502 [5/11] bpf: Add bpf_core_add_cands() and wire it into bpf_core_apply_relo_insn().
:::::: branch date: 2 days ago
:::::: commit date: 2 days ago
config: riscv-randconfig-c006-20210919 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project c8b3d7d6d6de37af68b2f379d0e37304f78e115f)
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
        # install riscv cross compiling tool for clang build
        # apt-get install binutils-riscv64-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/ast/bpf.git/commit/?id=98beca424883749fbcf9f244bb26c96ed3102502
        git remote add ast-bpf https://git.kernel.org/pub/scm/linux/kernel/git/ast/bpf.git
        git fetch --no-tags ast-bpf relo_core
        git checkout 98beca424883749fbcf9f244bb26c96ed3102502
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=riscv clang-analyzer

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


clang-analyzer warnings: (new ones prefixed by >>)

>> kernel/bpf/btf.c:6524:2: warning: Value stored to 'err' is never read [clang-analyzer-deadcode.DeadStores]
           err = bpf_core_apply_relo_insn("prog_name", insn, 0, &core_relo, 0, btf, cands);
           ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

vim +/err +6524 kernel/bpf/btf.c

98beca42488374 Alexei Starovoitov 2021-09-16  6491
fab12a1832b619 Alexei Starovoitov 2021-09-08  6492  BPF_CALL_5(bpf_core_apply_relo, int, btf_fd, struct bpf_core_relo_desc *, relo,
fab12a1832b619 Alexei Starovoitov 2021-09-08  6493  	   int, relo_sz, void *, insn, int, flags)
fab12a1832b619 Alexei Starovoitov 2021-09-08  6494  {
98beca42488374 Alexei Starovoitov 2021-09-16  6495  	struct bpf_core_cand_list *cands = NULL;
98beca42488374 Alexei Starovoitov 2021-09-16  6496  	struct bpf_core_relo core_relo = {};
fab12a1832b619 Alexei Starovoitov 2021-09-08  6497  	struct btf *btf;
98beca42488374 Alexei Starovoitov 2021-09-16  6498  	int err;
fab12a1832b619 Alexei Starovoitov 2021-09-08  6499
fab12a1832b619 Alexei Starovoitov 2021-09-08  6500  	if (flags)
fab12a1832b619 Alexei Starovoitov 2021-09-08  6501  		return -EINVAL;
98beca42488374 Alexei Starovoitov 2021-09-16  6502
98beca42488374 Alexei Starovoitov 2021-09-16  6503  	if (sizeof(*relo) != relo_sz)
98beca42488374 Alexei Starovoitov 2021-09-16  6504  		return -EINVAL;
98beca42488374 Alexei Starovoitov 2021-09-16  6505  	btf = btf_get_by_fd(btf_fd);
98beca42488374 Alexei Starovoitov 2021-09-16  6506  	if (IS_ERR(btf))
98beca42488374 Alexei Starovoitov 2021-09-16  6507  		return PTR_ERR(btf);
98beca42488374 Alexei Starovoitov 2021-09-16  6508  	if (btf_is_kernel(btf)) {
98beca42488374 Alexei Starovoitov 2021-09-16  6509  		btf_put(btf);
98beca42488374 Alexei Starovoitov 2021-09-16  6510  		return -EACCES;
98beca42488374 Alexei Starovoitov 2021-09-16  6511  	}
98beca42488374 Alexei Starovoitov 2021-09-16  6512  	if (relo->kind != BPF_CORE_TYPE_ID_LOCAL) {
98beca42488374 Alexei Starovoitov 2021-09-16  6513  		cands = bpf_core_find_cands(btf, relo->type_id);
98beca42488374 Alexei Starovoitov 2021-09-16  6514  		if (IS_ERR(cands)) {
98beca42488374 Alexei Starovoitov 2021-09-16  6515  			btf_put(btf);
98beca42488374 Alexei Starovoitov 2021-09-16  6516  			printk("target candidate search failed for %d\n",
98beca42488374 Alexei Starovoitov 2021-09-16  6517  			       relo->type_id);
98beca42488374 Alexei Starovoitov 2021-09-16  6518                          return PTR_ERR(cands);
98beca42488374 Alexei Starovoitov 2021-09-16  6519                  }
98beca42488374 Alexei Starovoitov 2021-09-16  6520  	}
98beca42488374 Alexei Starovoitov 2021-09-16  6521  	core_relo.type_id = relo->type_id;
98beca42488374 Alexei Starovoitov 2021-09-16  6522  	core_relo.access_str_off = relo->access_str_off;
98beca42488374 Alexei Starovoitov 2021-09-16  6523  	core_relo.kind = relo->kind;
98beca42488374 Alexei Starovoitov 2021-09-16 @6524  	err = bpf_core_apply_relo_insn("prog_name", insn, 0, &core_relo, 0, btf, cands);
98beca42488374 Alexei Starovoitov 2021-09-16  6525  	btf_put(btf);
98beca42488374 Alexei Starovoitov 2021-09-16  6526  	return 0;
fab12a1832b619 Alexei Starovoitov 2021-09-08  6527  }
fab12a1832b619 Alexei Starovoitov 2021-09-08  6528

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

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