linux-kernel - kernel/bpf/bpf_iter.c:789:17: warning: no previous declaration for 'bpf_iter_num

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Message-ID: <202309120150.uX27LKII-lkp@intel.com>
Date:   Tue, 12 Sep 2023 01:57:42 +0800
From:   kernel test robot <lkp@...el.com>
To:     Andrii Nakryiko <andrii@...nel.org>
Cc:     oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Alexei Starovoitov <ast@...nel.org>
Subject: kernel/bpf/bpf_iter.c:789:17: warning: no previous declaration for
 'bpf_iter_num_new'

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   0bb80ecc33a8fb5a682236443c1e740d5c917d1d
commit: 6018e1f407cccf39b804d1f75ad4de7be4e6cc45 bpf: implement numbers iterator
date:   6 months ago
config: x86_64-randconfig-002-20230910 (https://download.01.org/0day-ci/archive/20230912/202309120150.uX27LKII-lkp@intel.com/config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230912/202309120150.uX27LKII-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/202309120150.uX27LKII-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/bpf/bpf_iter.c:789:17: warning: no previous declaration for 'bpf_iter_num_new' [-Wmissing-declarations]
    __bpf_kfunc int bpf_iter_num_new(struct bpf_iter_num *it, int start, int end)
                    ^~~~~~~~~~~~~~~~
>> kernel/bpf/bpf_iter.c:822:18: warning: no previous declaration for 'bpf_iter_num_next' [-Wmissing-declarations]
    __bpf_kfunc int *bpf_iter_num_next(struct bpf_iter_num* it)
                     ^~~~~~~~~~~~~~~~~
>> kernel/bpf/bpf_iter.c:841:18: warning: no previous declaration for 'bpf_iter_num_destroy' [-Wmissing-declarations]
    __bpf_kfunc void bpf_iter_num_destroy(struct bpf_iter_num *it)
                     ^~~~~~~~~~~~~~~~~~~~


vim +/bpf_iter_num_new +789 kernel/bpf/bpf_iter.c

   784	
   785	__diag_push();
   786	__diag_ignore_all("-Wmissing-prototypes",
   787			  "Global functions as their definitions will be in vmlinux BTF");
   788	
 > 789	__bpf_kfunc int bpf_iter_num_new(struct bpf_iter_num *it, int start, int end)
   790	{
   791		struct bpf_iter_num_kern *s = (void *)it;
   792	
   793		BUILD_BUG_ON(sizeof(struct bpf_iter_num_kern) != sizeof(struct bpf_iter_num));
   794		BUILD_BUG_ON(__alignof__(struct bpf_iter_num_kern) != __alignof__(struct bpf_iter_num));
   795	
   796		BTF_TYPE_EMIT(struct btf_iter_num);
   797	
   798		/* start == end is legit, it's an empty range and we'll just get NULL
   799		 * on first (and any subsequent) bpf_iter_num_next() call
   800		 */
   801		if (start > end) {
   802			s->cur = s->end = 0;
   803			return -EINVAL;
   804		}
   805	
   806		/* avoid overflows, e.g., if start == INT_MIN and end == INT_MAX */
   807		if ((s64)end - (s64)start > BPF_MAX_LOOPS) {
   808			s->cur = s->end = 0;
   809			return -E2BIG;
   810		}
   811	
   812		/* user will call bpf_iter_num_next() first,
   813		 * which will set s->cur to exactly start value;
   814		 * underflow shouldn't matter
   815		 */
   816		s->cur = start - 1;
   817		s->end = end;
   818	
   819		return 0;
   820	}
   821	
 > 822	__bpf_kfunc int *bpf_iter_num_next(struct bpf_iter_num* it)
   823	{
   824		struct bpf_iter_num_kern *s = (void *)it;
   825	
   826		/* check failed initialization or if we are done (same behavior);
   827		 * need to be careful about overflow, so convert to s64 for checks,
   828		 * e.g., if s->cur == s->end == INT_MAX, we can't just do
   829		 * s->cur + 1 >= s->end
   830		 */
   831		if ((s64)(s->cur + 1) >= s->end) {
   832			s->cur = s->end = 0;
   833			return NULL;
   834		}
   835	
   836		s->cur++;
   837	
   838		return &s->cur;
   839	}
   840	
 > 841	__bpf_kfunc void bpf_iter_num_destroy(struct bpf_iter_num *it)
   842	{
   843		struct bpf_iter_num_kern *s = (void *)it;
   844	
   845		s->cur = s->end = 0;
   846	}
   847	

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