add two members to struct usb_task

* usbd_device_handle dev - the device responsible for the task.  use
this to not run the task if the device's hub is dying.
* int running - a flag to be set when the task is running.

add usb_rem_wait_task(), a wrapper for usb_rem_task() that waits for
the task to complete if the task is already running.

s/usb_rem_task/usb_rem_wait_task/ in usb_detach().  probably most
drivers using usb_tasks should do this as well.  although device
attach/detach is serialized in normal cases, in the special case
where the usb bus is hotpluggable (like cardbus/pcmcia), devices
are not detached in the task thread.

2 files changed, 32 insertions, 6 deletions

diff --git a/sys/dev/usb/usb.c b/sys/dev/usb/usb.c
index 166827d019d..dd61f4e4037 100644
--- a/sys/dev/usb/usb.c
+++ b/sys/dev/usb/usb.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: usb.c,v 1.67 2010/09/23 05:44:15 jakemsr Exp $	*/
+/*	$OpenBSD: usb.c,v 1.68 2010/09/23 06:30:37 jakemsr Exp $	*/
 /*	$NetBSD: usb.c,v 1.77 2003/01/01 00:10:26 thorpej Exp $	*/
 
 /*
@@ -299,6 +299,7 @@ usb_add_task(usbd_device_handle dev, struct usb_task *task)
 		else
 			TAILQ_INSERT_TAIL(&usb_tasks, task, next);
 		task->onqueue = 1;
+		task->dev = dev;
 	}
 	wakeup(&usb_run_tasks);
 	splx(s);
@@ -323,6 +324,22 @@ usb_rem_task(usbd_device_handle dev, struct usb_task *task)
 }
 
 void
+usb_rem_wait_task(usbd_device_handle dev, struct usb_task *task)
+{
+	int s;
+
+	DPRINTFN(2,("%s: task=%p onqueue=%d\n", __func__, task, task->onqueue));
+
+	s = splusb();
+	usb_rem_task(dev, task);
+	while (task->running) {
+		DPRINTF(("%s: waiting for task to complete\n", __func__));
+		tsleep(task, PWAIT, "endtask", 0);
+	}
+	splx(s);
+}
+
+void
 usb_first_explore(void *arg)
 {
 	struct usb_softc *sc = arg;
@@ -381,9 +398,15 @@ usb_task_thread(void *arg)
 			continue;
 		}
 		task->onqueue = 0;
+		/* Don't execute the task if the root hub is gone. */
+		if (task->dev->bus->dying)
+			continue;
+		task->running = 1;
 		splx(s);
 		task->fun(task->arg);
 		s = splusb();
+		task->running = 0;
+		wakeup(task);
 	}
 	splx(s);
 
@@ -859,7 +882,7 @@ usb_detach(struct device *self, int flags)
 	if (sc->sc_port.device != NULL)
 		usb_disconnect_port(&sc->sc_port, self);
 
-	usb_rem_task(sc->sc_bus->root_hub, &sc->sc_explore_task);
+	usb_rem_wait_task(sc->sc_bus->root_hub, &sc->sc_explore_task);
 
 	usbd_finish();
 
diff --git a/sys/dev/usb/usbdi.h b/sys/dev/usb/usbdi.h
index 3b6010250d8..960b380bfa9 100644
--- a/sys/dev/usb/usbdi.h
+++ b/sys/dev/usb/usbdi.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: usbdi.h,v 1.33 2009/11/04 19:14:10 kettenis Exp $ */
+/*	$OpenBSD: usbdi.h,v 1.34 2010/09/23 06:30:37 jakemsr Exp $ */
 /*	$NetBSD: usbdi.h,v 1.62 2002/07/11 21:14:35 augustss Exp $	*/
 /*	$FreeBSD: src/sys/dev/usb/usbdi.h,v 1.18 1999/11/17 22:33:49 n_hibma Exp $	*/
 
@@ -181,14 +181,17 @@ const usb_descriptor_t *usb_desc_iter_next(usbd_desc_iter_t *);
  */
 struct usb_task {
 	TAILQ_ENTRY(usb_task) next;
+	usbd_device_handle dev;
 	void (*fun)(void *);
 	void *arg;
 	char onqueue;
+	char running;
 };
 
-void usb_add_task(usbd_device_handle dev, struct usb_task *task);
-void usb_rem_task(usbd_device_handle dev, struct usb_task *task);
-#define usb_init_task(t, f, a) ((t)->fun = (f), (t)->arg = (a), (t)->onqueue = 0)
+void usb_add_task(usbd_device_handle, struct usb_task *);
+void usb_rem_task(usbd_device_handle, struct usb_task *);
+void usb_rem_wait_task(usbd_device_handle, struct usb_task *);
+#define usb_init_task(t, f, a) ((t)->fun = (f), (t)->arg = (a), (t)->onqueue = 0, (t)->running = 0)
 
 struct usb_devno {
 	u_int16_t ud_vendor;