On Mon, 2018-01-01 at 11:48 +0800, kbuild test robot wrote:

Hi Jason,

I love your patch! Perhaps something to improve:

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

url:    https://github.com/0day-ci/linux/commits/Jason-Wang/XDP-transmission-for-tuntap/20180101-105946
config: i386-randconfig-x072-201800 (attached as .config)
compiler: gcc-7 (Debian 7.2.0-12) 7.2.1 20171025
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All warnings (new ones prefixed by >>):

   drivers//net/tun.c: In function 'tun_xdp_to_ptr':

quoted

quoted

drivers//net/tun.c:251:9: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]

     return (void *)((unsigned long)ptr | TUN_XDP_FLAG);
            ^
   drivers//net/tun.c: In function 'tun_ptr_to_xdp':
   drivers//net/tun.c:257:9: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
     return (void *)((unsigned long)ptr & ~TUN_XDP_FLAG);
            ^

vim +251 drivers//net/tun.c

   248	
   249	void *tun_xdp_to_ptr(void *ptr)
   250	{
 > 251		return (void *)((unsigned long)ptr | TUN_XDP_FLAG);

Does TUN_XDP_FLAG really need to be 0x1ULL?
Wouldn't 0x1UL suffice?