Hi Chunfeng, [FYI, it's a private test report for your RFC patch.] [auto build test ERROR on usb/usb-testing] [also build test ERROR on v5.4-rc5 next-20191031] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system. BTW, we also suggest to use '--base' option to specify the base tree in git format-patch, please see https://stackoverflow.com/a/37406982] url: https://github.com/0day-ci/linux/commits/Chunfeng-Yun/usb-common-change-u... base: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing config: i386-defconfig (attached as .config) compiler: gcc-7 (Debian 7.4.0-14) 7.4.0 reproduce: # save the attached .config to linux build tree make ARCH=i386 If you fix the issue, kindly add following tag Reported-by: kbuild test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): drivers/usb/core/usb.c: In function 'usb_debugfs_init': usb_devices_root = debugfs_create_file("devices", 0444, usb_debug_root, ^~~~~~~~~~~~~~ usb_debugfs_init drivers/usb/core/usb.c:970:58: note: each undeclared identifier is reported only once for each function it appears in -- drivers/usb/host/ohci-hcd.c: In function 'ohci_hcd_mod_init': ohci_debug_root = debugfs_create_dir("ohci", usb_debug_root); ^~~~~~~~~~~~~~ ohci_debug_root drivers/usb/host/ohci-hcd.c:1282:47: note: each undeclared identifier is reported only once for each function it appears in -- drivers/usb/host/xhci-debugfs.c: In function 'xhci_debugfs_create_root': xhci_debugfs_root = debugfs_create_dir("xhci", usb_debug_root); ^~~~~~~~~~~~~~ xhci_debugfs_root drivers/usb/host/xhci-debugfs.c:604:49: note: each undeclared identifier is reported only once for each function it appears in -- drivers/usb/mon/mon_text.c: In function 'mon_text_init': mon_dir = debugfs_create_dir("usbmon", usb_debug_root); ^~~~~~~~~~~~~~ ctl_table_root drivers/usb/mon/mon_text.c:766:41: note: each undeclared identifier is reported only once for each function it appears in vim +970 drivers/usb/core/usb.c 00048b8bde5a6c Greg Kroah-Hartman 2009-04-24 967 b708692dda1edf Greg Kroah-Hartman 2018-05-29 968 static void usb_debugfs_init(void) 00048b8bde5a6c Greg Kroah-Hartman 2009-04-24 969 { 812086d362a1d5 Greg Kroah-Hartman 2019-06-05 @970 usb_devices_root = debugfs_create_file("devices", 0444, usb_debug_root, 812086d362a1d5 Greg Kroah-Hartman 2019-06-05 971 NULL, &usbfs_devices_fops); 00048b8bde5a6c Greg Kroah-Hartman 2009-04-24 972 } 00048b8bde5a6c Greg Kroah-Hartman 2009-04-24 973 :::::: The code at line 970 was first introduced by commit :::::: 812086d362a1d589d2b2e10957254ac13e83522b USB: move usb debugfs directory creation to the usb common core :::::: TO: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org&gt; :::::: CC: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org&gt; --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation