linux-kernel - kernel/bpf/verifier.c:1776:21: error: unused variable 'kfunc

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Message-ID: <202110091158.BSPrMUTN-lkp@intel.com>
Date:   Sat, 9 Oct 2021 11:59:09 +0800
From:   kernel test robot <lkp@...el.com>
To:     Kumar Kartikeya Dwivedi <memxor@...il.com>
Cc:     kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org,
        0day robot <lkp@...el.com>
Subject: kernel/bpf/verifier.c:1776:21: error: unused variable 'kfunc_btf'

tree:   https://github.com/0day-ci/linux/commits/UPDATE-20211009-062812/Kumar-Kartikeya-Dwivedi/bpf-Silence-Coverity-warning-for-find_kfunc_desc_btf/20211009-010928
head:   aff5b53e62a423701f59205b644916bae36c96c3
commit: aff5b53e62a423701f59205b644916bae36c96c3 bpf: Silence Coverity warning for find_kfunc_desc_btf
date:   6 hours ago
config: microblaze-buildonly-randconfig-r003-20211008 (attached as .config)
compiler: microblaze-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://github.com/0day-ci/linux/commit/aff5b53e62a423701f59205b644916bae36c96c3
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review UPDATE-20211009-062812/Kumar-Kartikeya-Dwivedi/bpf-Silence-Coverity-warning-for-find_kfunc_desc_btf/20211009-010928
        git checkout aff5b53e62a423701f59205b644916bae36c96c3
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=microblaze 

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

All errors (new ones prefixed by >>):

   kernel/bpf/verifier.c: In function 'find_kfunc_desc_btf':
>> kernel/bpf/verifier.c:1776:21: error: unused variable 'kfunc_btf' [-Werror=unused-variable]
    1776 |         struct btf *kfunc_btf;
         |                     ^~~~~~~~~
   cc1: all warnings being treated as errors


vim +/kfunc_btf +1776 kernel/bpf/verifier.c

2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1771  
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1772  static struct btf *find_kfunc_desc_btf(struct bpf_verifier_env *env,
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1773  				       u32 func_id, s16 offset,
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1774  				       struct module **btf_modp)
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1775  {
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02 @1776  	struct btf *kfunc_btf;
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1777  
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1778  	if (offset) {
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1779  		if (offset < 0) {
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1780  			/* In the future, this can be allowed to increase limit
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1781  			 * of fd index into fd_array, interpreted as u16.
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1782  			 */
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1783  			verbose(env, "negative offset disallowed for kernel module function call\n");
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1784  			return ERR_PTR(-EINVAL);
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1785  		}
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1786  
aff5b53e62a42370 Kumar Kartikeya Dwivedi 2021-10-09  1787  		return __find_kfunc_desc_btf(env, offset, btf_modp);
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1788  	}
2357672c54c3f748 Kumar Kartikeya Dwivedi 2021-10-02  1789  	return btf_vmlinux ?: ERR_PTR(-ENOENT);
e6ac2450d6dee312 Martin KaFai Lau        2021-03-24  1790  }
e6ac2450d6dee312 Martin KaFai Lau        2021-03-24  1791  

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

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