Re: [PATCH bpf-next 1/8] bpf: Enable annotating trusted nested pointers

[David Vernet]

On Fri, Jan 20, 2023 at 09:14:25AM +0800, kernel test robot wrote:
> Hi David,
> 
> Thank you for the patch! Perhaps something to improve:
> 
> [auto build test WARNING on bpf-next/master]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/David-Vernet/bpf-Enable-annotating-trusted-nested-pointers/20230120-080139
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
> patch link:    https://lore.kernel.org/r/20230119235833.2948341-2-void%40manifault.com
> patch subject: [PATCH bpf-next 1/8] bpf: Enable annotating trusted nested pointers
> config: ia64-allyesconfig (https://download.01.org/0day-ci/archive/20230120/202301200957.At49rpzu-lkp@xxxxxxxxx/config)
> compiler: ia64-linux-gcc (GCC) 12.1.0
> 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/intel-lab-lkp/linux/commit/8f6df14342b1be3516f8e21037edf771df851427
>         git remote add linux-review https://github.com/intel-lab-lkp/linux
>         git fetch --no-tags linux-review David-Vernet/bpf-Enable-annotating-trusted-nested-pointers/20230120-080139
>         git checkout 8f6df14342b1be3516f8e21037edf771df851427
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=ia64 olddefconfig
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=ia64 SHELL=/bin/bash kernel/bpf/
> 
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> 
> All warnings (new ones prefixed by >>):
> 
> >> kernel/bpf/btf.c:533:5: warning: no previous prototype for 'bpf_find_btf_id' [-Wmissing-prototypes]
>      533 | s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p)

Silly mistake on my part. I removed static while debugging something in
verifier.c and forgot to put it back. I'll put it back in v2.

>          |     ^~~~~~~~~~~~~~~
>    kernel/bpf/btf.c: In function 'btf_seq_show':
>    kernel/bpf/btf.c:6977:29: warning: function 'btf_seq_show' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
>     6977 |         seq_vprintf((struct seq_file *)show->target, fmt, args);
>          |                             ^~~~~~~~
>    kernel/bpf/btf.c: In function 'btf_snprintf_show':
>    kernel/bpf/btf.c:7014:9: warning: function 'btf_snprintf_show' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
>     7014 |         len = vsnprintf(show->target, ssnprintf->len_left, fmt, args);
>          |         ^~~
> 
> 
> vim +/bpf_find_btf_id +533 kernel/bpf/btf.c
> 
>    532	
>  > 533	s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p)
>    534	{
>    535		struct btf *btf;
>    536		s32 ret;
>    537		int id;
>    538	
>    539		btf = bpf_get_btf_vmlinux();
>    540		if (IS_ERR(btf))
>    541			return PTR_ERR(btf);
>    542		if (!btf)
>    543			return -EINVAL;
>    544	
>    545		ret = btf_find_by_name_kind(btf, name, kind);
>    546		/* ret is never zero, since btf_find_by_name_kind returns
>    547		 * positive btf_id or negative error.
>    548		 */
>    549		if (ret > 0) {
>    550			btf_get(btf);
>    551			*btf_p = btf;
>    552			return ret;
>    553		}
>    554	
>    555		/* If name is not found in vmlinux's BTF then search in module's BTFs */
>    556		spin_lock_bh(&btf_idr_lock);
>    557		idr_for_each_entry(&btf_idr, btf, id) {
>    558			if (!btf_is_module(btf))
>    559				continue;
>    560			/* linear search could be slow hence unlock/lock
>    561			 * the IDR to avoiding holding it for too long
>    562			 */
>    563			btf_get(btf);
>    564			spin_unlock_bh(&btf_idr_lock);
>    565			ret = btf_find_by_name_kind(btf, name, kind);
>    566			if (ret > 0) {
>    567				*btf_p = btf;
>    568				return ret;
>    569			}
>    570			spin_lock_bh(&btf_idr_lock);
>    571			btf_put(btf);
>    572		}
>    573		spin_unlock_bh(&btf_idr_lock);
>    574		return ret;
>    575	}
>    576	
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests