tree:   https://android.googlesource.com/kernel/common android12-5.10-lts
head:   1b6d7b3a2162f55441d3d0774c41a4fc6378798f
commit: 1df699c140a778ed678d7d4b2fa8ffb2c62573e1 [5161/13543] UPSTREAM: driver core: Handle cycles in device links created by fw_devlink
config: arm-randconfig-r036-20210928 (attached as .config)
compiler: arm-linux-gnueabi-gcc (GCC) 11.2.0
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
        git remote add android-common https://android.googlesource.com/kernel/common
        git fetch --no-tags android-common android12-5.10-lts
        git checkout 1df699c140a778ed678d7d4b2fa8ffb2c62573e1
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=arm 

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 >>):

>> drivers/base/core.c:1542:5: warning: no previous prototype for 'fw_devlink_relax_cycle' [-Wmissing-prototypes]
    1542 | int fw_devlink_relax_cycle(struct device *con, void *sup)
         |     ^~~~~~~~~~~~~~~~~~~~~~


vim +/fw_devlink_relax_cycle +1542 drivers/base/core.c

  1527	
  1528	/**
  1529	 * fw_devlink_relax_cycle - Convert cyclic links to SYNC_STATE_ONLY links
  1530	 * @con: Device to check dependencies for.
  1531	 * @sup: Device to check against.
  1532	 *
  1533	 * Check if @sup depends on @con or any device dependent on it (its child or
  1534	 * its consumer etc).  When such a cyclic dependency is found, convert all
  1535	 * device links created solely by fw_devlink into SYNC_STATE_ONLY device links.
  1536	 * This is the equivalent of doing fw_devlink=permissive just between the
  1537	 * devices in the cycle. We need to do this because, at this point, fw_devlink
  1538	 * can't tell which of these dependencies is not a real dependency.
  1539	 *
  1540	 * Return 1 if a cycle is found. Otherwise, return 0.
  1541	 */
> 1542	int fw_devlink_relax_cycle(struct device *con, void *sup)
  1543	{
  1544		struct device_link *link;
  1545		int ret;
  1546	
  1547		if (con == sup)
  1548			return 1;
  1549	
  1550		ret = device_for_each_child(con, sup, fw_devlink_relax_cycle);
  1551		if (ret)
  1552			return ret;
  1553	
  1554		list_for_each_entry(link, &con->links.consumers, s_node) {
  1555			if ((link->flags & ~DL_FLAG_INFERRED) ==
  1556			    (DL_FLAG_SYNC_STATE_ONLY | DL_FLAG_MANAGED))
  1557				continue;
  1558	
  1559			if (!fw_devlink_relax_cycle(link->consumer, sup))
  1560				continue;
  1561	
  1562			ret = 1;
  1563	
  1564			if (!(link->flags & DL_FLAG_INFERRED))
  1565				continue;
  1566	
  1567			pm_runtime_drop_link(link);
  1568			link->flags = DL_FLAG_MANAGED | FW_DEVLINK_FLAGS_PERMISSIVE;
  1569			dev_dbg(link->consumer, "Relaxing link with %s\n",
  1570				dev_name(link->supplier));
  1571		}
  1572		return ret;
  1573	}
  1574	

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