Re: [RFC PATCH 1/2] net: netlink: add nla_get_*_default() accessors

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

Hi Johannes,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build errors:

[auto build test ERROR on wireless-next/main]
[also build test ERROR on wireless/main netfilter-nf/main linus/master horms-ipvs/master nf-next/master v6.12-rc4 next-20241024]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Johannes-Berg/net-convert-to-nla_get_-_default/20241024-191943
base:   https://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless-next.git main
patch link:    https://lore.kernel.org/r/20241024131807.0a6c07355832.I3df6aac71d38a5baa1c0a03d0c7e82d4395c030e%40changeid
patch subject: [RFC PATCH 1/2] net: netlink: add nla_get_*_default() accessors
config: x86_64-rhel-8.3 (https://download.01.org/0day-ci/archive/20241024/202410242345.2HEJkySu-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241024/202410242345.2HEJkySu-lkp@intel.com/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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202410242345.2HEJkySu-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from include/net/rtnetlink.h:6,
                    from include/net/neighbour.h:31,
                    from include/net/dst.h:20,
                    from include/net/sock.h:66,
                    from include/linux/tcp.h:19,
                    from include/linux/ipv6.h:102,
                    from include/net/gro.h:8,
                    from net/8021q/vlan_core.c:7:
   include/net/netlink.h: In function 'nla_get_u8_default':
>> include/net/netlink.h:1878:16: error: implicit declaration of function 'n' [-Werror=implicit-function-declaration]
    1878 |         return n(nla);                                  \
         |                ^
   include/net/netlink.h:1881:1: note: in expansion of macro 'MAKE_NLA_GET_DEFAULT'
    1881 | MAKE_NLA_GET_DEFAULT(u8, nla_get_u8);
         | ^~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors
--
   In file included from include/net/rtnetlink.h:6,
                    from include/net/neighbour.h:31,
                    from include/net/arp.h:8,
                    from net/8021q/vlan.c:27:
   include/net/netlink.h: In function 'nla_get_u8_default':
>> include/net/netlink.h:1878:16: error: implicit declaration of function 'n' [-Werror=implicit-function-declaration]
    1878 |         return n(nla);                                  \
         |                ^
   include/net/netlink.h:1881:1: note: in expansion of macro 'MAKE_NLA_GET_DEFAULT'
    1881 | MAKE_NLA_GET_DEFAULT(u8, nla_get_u8);
         | ^~~~~~~~~~~~~~~~~~~~
   net/8021q/vlan.c: In function 'register_vlan_device':
   net/8021q/vlan.c:247:46: warning: '%i' directive output may be truncated writing between 1 and 4 bytes into a region of size between 0 and 15 [-Wformat-truncation=]
     247 |                 snprintf(name, IFNAMSIZ, "%s.%i", real_dev->name, vlan_id);
         |                                              ^~
   net/8021q/vlan.c:247:42: note: directive argument in the range [0, 4094]
     247 |                 snprintf(name, IFNAMSIZ, "%s.%i", real_dev->name, vlan_id);
         |                                          ^~~~~~~
   net/8021q/vlan.c:247:17: note: 'snprintf' output between 3 and 21 bytes into a destination of size 16
     247 |                 snprintf(name, IFNAMSIZ, "%s.%i", real_dev->name, vlan_id);
         |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   net/8021q/vlan.c:235:46: warning: '%.4i' directive output may be truncated writing 4 bytes into a region of size between 0 and 15 [-Wformat-truncation=]
     235 |                 snprintf(name, IFNAMSIZ, "%s.%.4i", real_dev->name, vlan_id);
         |                                              ^~~~
   net/8021q/vlan.c:235:42: note: directive argument in the range [0, 4094]
     235 |                 snprintf(name, IFNAMSIZ, "%s.%.4i", real_dev->name, vlan_id);
         |                                          ^~~~~~~~~
   net/8021q/vlan.c:235:17: note: 'snprintf' output between 6 and 21 bytes into a destination of size 16
     235 |                 snprintf(name, IFNAMSIZ, "%s.%.4i", real_dev->name, vlan_id);
         |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors


vim +/n +1878 include/net/netlink.h

  1871	
  1872	#define MAKE_NLA_GET_DEFAULT(tp, fn)			\
  1873	static inline tp fn##_default(const struct nlattr *nla,	\
  1874				      tp defvalue)		\
  1875	{							\
  1876		if (!nla)					\
  1877			return defvalue;			\
> 1878		return n(nla);					\
  1879	}
  1880	

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