Re: [PATCH bpf-next 5/5] bpf: Count the number of times recursion was prevented

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

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Hi Alexei,

I love your patch! Perhaps something to improve:

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

url:    https://github.com/0day-ci/linux/commits/Alexei-Starovoitov/bpf-Misc-improvements/20210206-150251
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: openrisc-randconfig-p001-20210206 (attached as .config)
compiler: or1k-linux-gcc (GCC) 9.3.0
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/0day-ci/linux/commit/8d71f0650d2551940d9fc39a723d6595ab604715
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Alexei-Starovoitov/bpf-Misc-improvements/20210206-150251
        git checkout 8d71f0650d2551940d9fc39a723d6595ab604715
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=openrisc 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   kernel/bpf/syscall.c: In function 'bpf_prog_get_stats':
>> kernel/bpf/syscall.c:1740:21: warning: variable 'tmisses' set but not used [-Wunused-but-set-variable]
    1740 |   u64 tnsecs, tcnt, tmisses;
         |                     ^~~~~~~


vim +/tmisses +1740 kernel/bpf/syscall.c

  1730	
  1731	static void bpf_prog_get_stats(const struct bpf_prog *prog,
  1732				       struct bpf_prog_stats *stats)
  1733	{
  1734		u64 nsecs = 0, cnt = 0, misses = 0;
  1735		int cpu;
  1736	
  1737		for_each_possible_cpu(cpu) {
  1738			const struct bpf_prog_stats *st;
  1739			unsigned int start;
> 1740			u64 tnsecs, tcnt, tmisses;
  1741	
  1742			st = per_cpu_ptr(prog->stats, cpu);
  1743			do {
  1744				start = u64_stats_fetch_begin_irq(&st->syncp);
  1745				tnsecs = st->nsecs;
  1746				tcnt = st->cnt;
  1747				tmisses = st->misses;
  1748			} while (u64_stats_fetch_retry_irq(&st->syncp, start));
  1749			nsecs += tnsecs;
  1750			cnt += tcnt;
  1751			misses += misses;
  1752		}
  1753		stats->nsecs = nsecs;
  1754		stats->cnt = cnt;
  1755		stats->misses = misses;
  1756	}
  1757	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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