Re: [PATCH v4 bpf-next 4/8] bpf: implement number iterator

[kernel test robot <lkp@intel.com>]

Hi Andrii,

I love your patch! Yet something to improve:

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

url:    https://github.com/intel-lab-lkp/linux/commits/Andrii-Nakryiko/bpf-factor-out-fetching-basic-kfunc-metadata/20230308-115539
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20230308035416.2591326-5-andrii%40kernel.org
patch subject: [PATCH v4 bpf-next 4/8] bpf: implement number iterator
config: i386-randconfig-a015-20230306 (https://download.01.org/0day-ci/archive/20230308/202303082315.foifky6G-lkp@intel.com/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
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/intel-lab-lkp/linux/commit/19acf9ca01e2927a29d3235b3aa73598430dcb70
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Andrii-Nakryiko/bpf-factor-out-fetching-basic-kfunc-metadata/20230308-115539
        git checkout 19acf9ca01e2927a29d3235b3aa73598430dcb70
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash kernel/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202303082315.foifky6G-lkp@intel.com/

All errors (new ones prefixed by >>):

>> kernel/bpf/bpf_iter.c:794:2: error: call to __compiletime_assert_395 declared with 'error' attribute: BUILD_BUG_ON failed: __alignof__(struct bpf_iter_num_kern) != __alignof__(struct bpf_iter_num)
           BUILD_BUG_ON(__alignof__(struct bpf_iter_num_kern) != __alignof__(struct bpf_iter_num));
           ^
   include/linux/build_bug.h:50:2: note: expanded from macro 'BUILD_BUG_ON'
           BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
           ^
   include/linux/build_bug.h:39:37: note: expanded from macro 'BUILD_BUG_ON_MSG'
   #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
                                       ^
   include/linux/compiler_types.h:399:2: note: expanded from macro 'compiletime_assert'
           _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
           ^
   include/linux/compiler_types.h:387:2: note: expanded from macro '_compiletime_assert'
           __compiletime_assert(condition, msg, prefix, suffix)
           ^
   include/linux/compiler_types.h:380:4: note: expanded from macro '__compiletime_assert'
                           prefix ## suffix();                             \
                           ^
   <scratch space>:74:1: note: expanded from here
   __compiletime_assert_395
   ^
   1 error generated.


vim +/error +794 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	

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