Hi,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v5.13-rc5 next-20210609]
[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]

url:    https://github.com/0day-ci/linux/commits/qiang-zhang-windriver-com/eventfd-convert-global-percpu-eventfd_wake_count-to-ctx-percpu-eventfd_wake_count/20210609-112354
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 368094df48e680fa51cedb68537408cfa64b788e
config: x86_64-randconfig-a015-20210608 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project d2012d965d60c3258b3a69d024491698f8aec386)
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
        # https://github.com/0day-ci/linux/commit/e11cefc5baf3f6cfb1ec8cd99b80422b6f592517
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review qiang-zhang-windriver-com/eventfd-convert-global-percpu-eventfd_wake_count-to-ctx-percpu-eventfd_wake_count/20210609-112354
        git checkout e11cefc5baf3f6cfb1ec8cd99b80422b6f592517
        # 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 errors (new ones prefixed by >>):

   In file included from drivers/vhost/net.c:9:
>> include/linux/eventfd.h:37:14: error: field has incomplete type 'struct kref'
           struct kref kref;
                       ^
   include/linux/eventfd.h:37:9: note: forward declaration of 'struct kref'
           struct kref kref;
                  ^
   1 error generated.


vim +37 include/linux/eventfd.h

    35	
    36	struct eventfd_ctx {
  > 37		struct kref kref;
    38		wait_queue_head_t wqh;
    39	       /*
    40		* Every time that a write(2) is performed on an eventfd, the
    41		* value of the __u64 being written is added to "count" and a
    42		* wakeup is performed on "wqh". A read(2) will return the "count"
    43		* value to userspace, and will reset "count" to zero. The kernel
    44		* side eventfd_signal() also, adds to the "count" counter and
    45		* issue a wakeup.
    46		*/
    47		__u64 count;
    48		unsigned int flags;
    49		int id;
    50		int __percpu *eventfd_wake_count;
    51	};
    52	

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