Use root_mount_hold and root_mount_rel to allow the USB bus to be explored

before trying to mount root. Unlike USB1 the busses are not explored at attach
but rather after threads are running.

2 files changed, 13 insertions, 0 deletions

diff --git a/sys/dev/usb2/controller/usb2_bus.h b/sys/dev/usb2/controller/usb2_bus.h
index c81a7a5..59287c4 100644
--- a/sys/dev/usb2/controller/usb2_bus.h
+++ b/sys/dev/usb2/controller/usb2_bus.h
@@ -53,6 +53,7 @@ struct usb2_bus {
 	struct usb2_bus_stat stats_ok;
 	struct usb2_process explore_proc;
 	struct usb2_process roothub_proc;
+	struct root_hold_token *bus_roothold;
 	/*
 	 * There are two callback processes. One for Giant locked
 	 * callbacks. One for non-Giant locked callbacks. This should
diff --git a/sys/dev/usb2/controller/usb2_controller.c b/sys/dev/usb2/controller/usb2_controller.c
index f8d94cf..cd334ab 100644
--- a/sys/dev/usb2/controller/usb2_controller.c
+++ b/sys/dev/usb2/controller/usb2_controller.c
@@ -126,6 +126,10 @@ usb2_attach(device_t dev)
 		DPRINTFN(0, "USB device has no ivars\n");
 		return (ENXIO);
 	}
+
+	/* delay vfs_mountroot until the bus is explored */
+	bus->bus_roothold = root_mount_hold(device_get_nameunit(dev));
+
 	if (usb2_post_init_called) {
 		mtx_lock(&Giant);
 		usb2_attach_sub(dev, bus);
@@ -153,6 +157,10 @@ usb2_detach(device_t dev)
 	usb2_callout_drain(&bus->power_wdog);
 
 	/* Let the USB explore process detach all devices. */
+	if (bus->bus_roothold != NULL) {
+		root_mount_rel(bus->bus_roothold);
+		bus->bus_roothold = NULL;
+	}
 
 	USB_BUS_LOCK(bus);
 	if (usb2_proc_msignal(&bus->explore_proc,
@@ -225,6 +233,10 @@ usb2_bus_explore(struct usb2_proc_msg *pm)
 
 		USB_BUS_LOCK(bus);
 	}
+	if (bus->bus_roothold != NULL) {
+		root_mount_rel(bus->bus_roothold);
+		bus->bus_roothold = NULL;
+	}
 }
 
 /*------------------------------------------------------------------------*