Hi Jesper,

I love your patch! Perhaps something to improve:

[auto build test WARNING on bpf/master]

url:    https://github.com/0day-ci/linux/commits/Jesper-Dangaard-Brouer/bpf-avoid-using-returning-file-descriptor-value-zero/20200609-005457
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git master
config: x86_64-randconfig-r003-20200608 (attached as .config)
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project e429cffd4f228f70c1d9df0e5d77c08590dd9766)
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
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

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 >>, old ones prefixed by <<):

>> kernel/bpf/syscall.c:692:5: warning: no previous prototype for function 'bpf_anon_inode_getfd' [-Wmissing-prototypes]
int bpf_anon_inode_getfd(const char *name, const struct file_operations *fops,
^
kernel/bpf/syscall.c:692:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
int bpf_anon_inode_getfd(const char *name, const struct file_operations *fops,
^
static
1 warning generated.

vim +/bpf_anon_inode_getfd +692 kernel/bpf/syscall.c

   690	
   691	/* Code is similar to anon_inode_getfd(), except starts at FD 1 */
 > 692	int bpf_anon_inode_getfd(const char *name, const struct file_operations *fops,
   693				 void *priv, int flags)
   694	{
   695		int error, fd;
   696		struct file *file;
   697	
   698		error = alloc_fd(1, flags);
   699		if (error < 0)
   700			return error;
   701		fd = error;
   702	
   703		file = anon_inode_getfile(name, fops, priv, flags);
   704		if (IS_ERR(file)) {
   705			error = PTR_ERR(file);
   706			goto err_put_unused_fd;
   707		}
   708		fd_install(fd, file);
   709	
   710		return fd;
   711	
   712	err_put_unused_fd:
   713		put_unused_fd(fd);
   714		return error;
   715	}
   716	

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