linux-kernel - Re: [PATCH 2/3] bpf: do not walk twice the hash map on free

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Date: Fri, 26 Apr 2024 07:09:46 +0800
From: kernel test robot <lkp@...el.com>
To: Benjamin Tissoires <bentiss@...nel.org>,
	Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrii Nakryiko <andrii@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>,
	Yonghong Song <yonghong.song@...ux.dev>,
	John Fastabend <john.fastabend@...il.com>,
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...gle.com>,
	Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
	Mykola Lysenko <mykolal@...com>,
	Shuah Khan <skhan@...uxfoundation.org>
Cc: oe-kbuild-all@...ts.linux.dev, bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
	Benjamin Tissoires <bentiss@...nel.org>
Subject: Re: [PATCH 2/3] bpf: do not walk twice the hash map on free

Hi Benjamin,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 52578f7f53ff8fe3a8f6f3bc8b5956615c07a16e]

url:    https://github.com/intel-lab-lkp/linux/commits/Benjamin-Tissoires/bpf-do-not-walk-twice-the-map-on-free/20240425-220322
base:   52578f7f53ff8fe3a8f6f3bc8b5956615c07a16e
patch link:    https://lore.kernel.org/r/20240425-bpf-next-v1-2-1d8330e6c643%40kernel.org
patch subject: [PATCH 2/3] bpf: do not walk twice the hash map on free
config: arc-randconfig-002-20240426 (https://download.01.org/0day-ci/archive/20240426/202404260653.ULrCGrp2-lkp@intel.com/config)
compiler: arc-elf-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240426/202404260653.ULrCGrp2-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202404260653.ULrCGrp2-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/bpf/hashtab.c:243:13: warning: 'htab_free_prealloced_wq' defined but not used [-Wunused-function]
     243 | static void htab_free_prealloced_wq(struct bpf_htab *htab)
         |             ^~~~~~~~~~~~~~~~~~~~~~~


vim +/htab_free_prealloced_wq +243 kernel/bpf/hashtab.c

68134668c17f31 Alexei Starovoitov 2021-07-14  242  
246331e3f1eac9 Benjamin Tissoires 2024-04-20 @243  static void htab_free_prealloced_wq(struct bpf_htab *htab)
246331e3f1eac9 Benjamin Tissoires 2024-04-20  244  {
246331e3f1eac9 Benjamin Tissoires 2024-04-20  245  	u32 num_entries = htab->map.max_entries;
246331e3f1eac9 Benjamin Tissoires 2024-04-20  246  	int i;
246331e3f1eac9 Benjamin Tissoires 2024-04-20  247  
246331e3f1eac9 Benjamin Tissoires 2024-04-20  248  	if (!btf_record_has_field(htab->map.record, BPF_WORKQUEUE))
246331e3f1eac9 Benjamin Tissoires 2024-04-20  249  		return;
246331e3f1eac9 Benjamin Tissoires 2024-04-20  250  	if (htab_has_extra_elems(htab))
246331e3f1eac9 Benjamin Tissoires 2024-04-20  251  		num_entries += num_possible_cpus();
246331e3f1eac9 Benjamin Tissoires 2024-04-20  252  
246331e3f1eac9 Benjamin Tissoires 2024-04-20  253  	for (i = 0; i < num_entries; i++) {
246331e3f1eac9 Benjamin Tissoires 2024-04-20  254  		struct htab_elem *elem;
246331e3f1eac9 Benjamin Tissoires 2024-04-20  255  
246331e3f1eac9 Benjamin Tissoires 2024-04-20  256  		elem = get_htab_elem(htab, i);
246331e3f1eac9 Benjamin Tissoires 2024-04-20  257  		bpf_obj_free_workqueue(htab->map.record,
246331e3f1eac9 Benjamin Tissoires 2024-04-20  258  				       elem->key + round_up(htab->map.key_size, 8));
246331e3f1eac9 Benjamin Tissoires 2024-04-20  259  		cond_resched();
246331e3f1eac9 Benjamin Tissoires 2024-04-20  260  	}
246331e3f1eac9 Benjamin Tissoires 2024-04-20  261  }
246331e3f1eac9 Benjamin Tissoires 2024-04-20  262  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki