Extern or forward variable declaration at drivers/usb/core/hcd.h, line 212 References: drivers/usb/core/hcd-pci.c, line 64 drivers/usb/core/hcd.h, line 212 drivers/usb/core/hcd.h, line 214 drivers/usb/host/ehci-hcd.c, line 1001 drivers/usb/host/uhci-hcd.c, line 2537