linux-kernel - [ast-bpf:relo_core 5/11] kernel/bpf/btf.c:6498:13: warning: variable 'err' set but not used

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Date:   Sat, 18 Sep 2021 10:12:28 +0800
From:   kernel test robot <lkp@...el.com>
To:     Alexei Starovoitov <ast@...nel.org>
Cc:     kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org
Subject: [ast-bpf:relo_core 5/11] kernel/bpf/btf.c:6498:13: warning: variable
 'err' set but not used

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().
config: riscv-randconfig-r042-20210916 (attached as .config)
compiler: riscv32-linux-gcc (GCC) 11.2.0
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=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=gcc-11.2.0 make.cross ARCH=riscv 

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/btf.c: In function 'btf_seq_show':
   kernel/bpf/btf.c:5877:29: warning: function 'btf_seq_show' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
    5877 |         seq_vprintf((struct seq_file *)show->target, fmt, args);
         |                             ^~~~~~~~
   kernel/bpf/btf.c: In function 'btf_snprintf_show':
   kernel/bpf/btf.c:5914:9: warning: function 'btf_snprintf_show' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
    5914 |         len = vsnprintf(show->target, ssnprintf->len_left, fmt, args);
         |         ^~~
   kernel/bpf/btf.c: In function '____bpf_core_apply_relo':
>> kernel/bpf/btf.c:6498:13: warning: variable 'err' set but not used [-Wunused-but-set-variable]
    6498 |         int err;
         |             ^~~


vim +/err +6498 kernel/bpf/btf.c

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

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

Download attachment ".config.gz" of type "application/gzip" (36895 bytes)