Re: [PATCH net-next 09/15] net: increase MAX_SKB_FRAGS

Hi Eric,

I love your patch! Yet something to improve:

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

url:    https://github.com/0day-ci/linux/commits/Eric-Dumazet/tcp-BIG-TCP-implementation/20220203-095336
base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git 52dae93f3bad842c6d585700460a0dea4d70e096
config: arc-randconfig-r043-20220130 (https://download.01.org/0day-ci/archive/20220203/202202031206.1nNLT568-lkp@intel.com/config)
compiler: arc-elf-gcc (GCC) 11.2.0
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/64ec6b0260be94b2ed90ee6d139591bdbd49c82d
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Eric-Dumazet/tcp-BIG-TCP-implementation/20220203-095336
        git checkout 64ec6b0260be94b2ed90ee6d139591bdbd49c82d
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=arc SHELL=/bin/bash kernel/bpf/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

All errors (new ones prefixed by >>):

   In file included from include/linux/container_of.h:5,
                    from include/linux/list.h:5,
                    from include/linux/rculist.h:10,
                    from include/linux/pid.h:5,
                    from include/linux/sched.h:14,
                    from include/linux/ptrace.h:6,
                    from include/uapi/asm-generic/bpf_perf_event.h:4,
                    from ./arch/arc/include/generated/uapi/asm/bpf_perf_event.h:1,
                    from include/uapi/linux/bpf_perf_event.h:11,
                    from kernel/bpf/btf.c:6:

quoted

include/linux/build_bug.h:78:41: error: static assertion failed: "BITS_PER_LONG >= NR_MSG_FRAG_IDS"

      78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
         |                                         ^~~~~~~~~~~~~~
   include/linux/build_bug.h:77:34: note: in expansion of macro '__static_assert'
      77 | #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
         |                                  ^~~~~~~~~~~~~~~
   include/linux/skmsg.h:41:1: note: in expansion of macro 'static_assert'
      41 | static_assert(BITS_PER_LONG >= NR_MSG_FRAG_IDS);
         | ^~~~~~~~~~~~~
   kernel/bpf/btf.c: In function 'btf_seq_show':
   kernel/bpf/btf.c:6049:29: warning: function 'btf_seq_show' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
    6049 |         seq_vprintf((struct seq_file *)show->target, fmt, args);
         |                             ^~~~~~~~
   kernel/bpf/btf.c: In function 'btf_snprintf_show':
   kernel/bpf/btf.c:6086:9: warning: function 'btf_snprintf_show' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
    6086 |         len = vsnprintf(show->target, ssnprintf->len_left, fmt, args);
         |         ^~~


vim +78 include/linux/build_bug.h

bc6245e5efd70c4 Ian Abbott       2017-07-10  60  
6bab69c65013bed Rasmus Villemoes 2019-03-07  61  /**
6bab69c65013bed Rasmus Villemoes 2019-03-07  62   * static_assert - check integer constant expression at build time
6bab69c65013bed Rasmus Villemoes 2019-03-07  63   *
6bab69c65013bed Rasmus Villemoes 2019-03-07  64   * static_assert() is a wrapper for the C11 _Static_assert, with a
6bab69c65013bed Rasmus Villemoes 2019-03-07  65   * little macro magic to make the message optional (defaulting to the
6bab69c65013bed Rasmus Villemoes 2019-03-07  66   * stringification of the tested expression).
6bab69c65013bed Rasmus Villemoes 2019-03-07  67   *
6bab69c65013bed Rasmus Villemoes 2019-03-07  68   * Contrary to BUILD_BUG_ON(), static_assert() can be used at global
6bab69c65013bed Rasmus Villemoes 2019-03-07  69   * scope, but requires the expression to be an integer constant
6bab69c65013bed Rasmus Villemoes 2019-03-07  70   * expression (i.e., it is not enough that __builtin_constant_p() is
6bab69c65013bed Rasmus Villemoes 2019-03-07  71   * true for expr).
6bab69c65013bed Rasmus Villemoes 2019-03-07  72   *
6bab69c65013bed Rasmus Villemoes 2019-03-07  73   * Also note that BUILD_BUG_ON() fails the build if the condition is
6bab69c65013bed Rasmus Villemoes 2019-03-07  74   * true, while static_assert() fails the build if the expression is
6bab69c65013bed Rasmus Villemoes 2019-03-07  75   * false.
6bab69c65013bed Rasmus Villemoes 2019-03-07  76   */
6bab69c65013bed Rasmus Villemoes 2019-03-07  77  #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
6bab69c65013bed Rasmus Villemoes 2019-03-07 @78  #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
6bab69c65013bed Rasmus Villemoes 2019-03-07  79  

---
0-DAY CI Kernel Test Service, Intel Corporation
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