Re: [PATCH bpf-next v4 4/8] bpf: Introduce css open-coded iterator kfuncs

[kernel test robot]

Hi Chuyi,

kernel test robot noticed the following build warnings:

[auto build test WARNING on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Chuyi-Zhou/cgroup-Prepare-for-using-css_task_iter_-in-BPF/20231007-204750
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20231007124522.34834-5-zhouchuyi%40bytedance.com
patch subject: [PATCH bpf-next v4 4/8] bpf: Introduce css open-coded iterator kfuncs
config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20231007/202310072337.CzRlbffm-lkp@xxxxxxxxx/config)
compiler: m68k-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231007/202310072337.CzRlbffm-lkp@xxxxxxxxx/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@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310072337.CzRlbffm-lkp@xxxxxxxxx/

All warnings (new ones prefixed by >>):

>> kernel/bpf/cgroup_iter.c:308:17: warning: no previous prototype for 'bpf_iter_css_new' [-Wmissing-prototypes]
     308 | __bpf_kfunc int bpf_iter_css_new(struct bpf_iter_css *it,
         |                 ^~~~~~~~~~~~~~~~
>> kernel/bpf/cgroup_iter.c:332:41: warning: no previous prototype for 'bpf_iter_css_next' [-Wmissing-prototypes]
     332 | __bpf_kfunc struct cgroup_subsys_state *bpf_iter_css_next(struct bpf_iter_css *it)
         |                                         ^~~~~~~~~~~~~~~~~
>> kernel/bpf/cgroup_iter.c:353:18: warning: no previous prototype for 'bpf_iter_css_destroy' [-Wmissing-prototypes]
     353 | __bpf_kfunc void bpf_iter_css_destroy(struct bpf_iter_css *it)
         |                  ^~~~~~~~~~~~~~~~~~~~
   In file included from <command-line>:
   kernel/bpf/cgroup_iter.c: In function 'bpf_iter_css_new':
   include/linux/compiler_types.h:425:45: error: call to '__compiletime_assert_320' declared with attribute error: BUILD_BUG_ON failed: sizeof(struct bpf_iter_css_kern) != sizeof(struct bpf_iter_css)
     425 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
         |                                             ^
   include/linux/compiler_types.h:406:25: note: in definition of macro '__compiletime_assert'
     406 |                         prefix ## suffix();                             \
         |                         ^~~~~~
   include/linux/compiler_types.h:425:9: note: in expansion of macro '_compiletime_assert'
     425 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
         |         ^~~~~~~~~~~~~~~~~~~
   include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert'
      39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
         |                                     ^~~~~~~~~~~~~~~~~~
   include/linux/build_bug.h:50:9: note: in expansion of macro 'BUILD_BUG_ON_MSG'
      50 |         BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
         |         ^~~~~~~~~~~~~~~~
   kernel/bpf/cgroup_iter.c:313:9: note: in expansion of macro 'BUILD_BUG_ON'
     313 |         BUILD_BUG_ON(sizeof(struct bpf_iter_css_kern) != sizeof(struct bpf_iter_css));
         |         ^~~~~~~~~~~~


vim +/bpf_iter_css_new +308 kernel/bpf/cgroup_iter.c

   307	
 > 308	__bpf_kfunc int bpf_iter_css_new(struct bpf_iter_css *it,
   309			struct cgroup_subsys_state *start, unsigned int flags)
   310	{
   311		struct bpf_iter_css_kern *kit = (void *)it;
   312	
   313		BUILD_BUG_ON(sizeof(struct bpf_iter_css_kern) != sizeof(struct bpf_iter_css));
   314		BUILD_BUG_ON(__alignof__(struct bpf_iter_css_kern) != __alignof__(struct bpf_iter_css));
   315	
   316		kit->start = NULL;
   317		switch (flags) {
   318		case BPF_CGROUP_ITER_DESCENDANTS_PRE:
   319		case BPF_CGROUP_ITER_DESCENDANTS_POST:
   320		case BPF_CGROUP_ITER_ANCESTORS_UP:
   321			break;
   322		default:
   323			return -EINVAL;
   324		}
   325	
   326		kit->start = start;
   327		kit->pos = NULL;
   328		kit->flags = flags;
   329		return 0;
   330	}
   331	
 > 332	__bpf_kfunc struct cgroup_subsys_state *bpf_iter_css_next(struct bpf_iter_css *it)
   333	{
   334		struct bpf_iter_css_kern *kit = (void *)it;
   335	
   336		if (!kit->start)
   337			return NULL;
   338	
   339		switch (kit->flags) {
   340		case BPF_CGROUP_ITER_DESCENDANTS_PRE:
   341			kit->pos = css_next_descendant_pre(kit->pos, kit->start);
   342			break;
   343		case BPF_CGROUP_ITER_DESCENDANTS_POST:
   344			kit->pos = css_next_descendant_post(kit->pos, kit->start);
   345			break;
   346		case BPF_CGROUP_ITER_ANCESTORS_UP:
   347			kit->pos = kit->pos ? kit->pos->parent : kit->start;
   348		}
   349	
   350		return kit->pos;
   351	}
   352	
 > 353	__bpf_kfunc void bpf_iter_css_destroy(struct bpf_iter_css *it)

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