Hi Geliang,

[FYI, it's a private test report for your RFC patch.]
[auto build test WARNING on mptcp/export]
[also build test WARNING on linus/master next-20210907]
[cannot apply to kselftest/next v5.14]
[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/Geliang-Tang/round-robin-packet-scheduler-support/20210907-184352
base:   https://github.com/multipath-tcp/mptcp_net-next.git export
config: x86_64-randconfig-c001-20210906 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/ddb57feaf4d36733ba9107a6bb1466a0c22ab204
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Geliang-Tang/round-robin-packet-scheduler-support/20210907-184352
        git checkout ddb57feaf4d36733ba9107a6bb1466a0c22ab204
        # save the attached .config to linux build tree
        make W=1 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 >>):

   net/mptcp/protocol.c: In function 'mptcp_register_scheduler':
>> net/mptcp/protocol.c:1541:6: warning: variable 'ret' set but not used [-Wunused-but-set-variable]
    1541 |  int ret = 0;
         |      ^~~


vim +/ret +1541 net/mptcp/protocol.c

  1538	
  1539	static int mptcp_register_scheduler(struct mptcp_sched_ops *sched)
  1540	{
> 1541		int ret = 0;
  1542	
  1543		if (!sched->get_subflow)
  1544			return -EINVAL;
  1545	
  1546		spin_lock(&mptcp_sched_list_lock);
  1547		if (mptcp_sched_find(sched->name)) {
  1548			pr_debug("%s already registered", sched->name);
  1549			ret = -EEXIST;
  1550		} else {
  1551			list_add_tail_rcu(&sched->list, &mptcp_sched_list);
  1552			pr_debug("%s registered", sched->name);
  1553		}
  1554		spin_unlock(&mptcp_sched_list_lock);
  1555		return 0;
  1556	}
  1557	

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