Subject: Re: [PATCH net-next 2/2] tuntap: XDP transmission

From: Joe Perches <[email-masked]>
Date: Sun, 31 Dec 2017 19:55:17 -0800

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':
> > > 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?