remove horrible abuse of kthread_create_deferred(9). this was being

used to "do things later" and was potentially sleeping in swapper
context.  the latter is really bad, because it might never wake up.

instead, move the things that usb_first_explore() was doing to the
first run of the explore task.  since tasks are run in a kthread,
they are in process context and ok to sleep.

fixes boot hang noticed by jsg@, which mikeb@ debugged and found
usb_first_explore() to be sleeping swapper context

1 files changed, 36 insertions, 46 deletions

diff --git a/sys/dev/usb/usb.c b/sys/dev/usb/usb.c
index 99b3eecd7db..07539c46ec7 100644
--- a/sys/dev/usb/usb.c
+++ b/sys/dev/usb/usb.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: usb.c,v 1.75 2011/02/09 20:24:39 jakemsr Exp $	*/
+/*	$OpenBSD: usb.c,v 1.76 2011/04/28 07:35:15 jakemsr Exp $	*/
 /*	$NetBSD: usb.c,v 1.77 2003/01/01 00:10:26 thorpej Exp $	*/
 
 /*
@@ -106,7 +106,6 @@ int usb_run_tasks, usb_run_abort_tasks;
 int explore_pending;
 
 void	usb_explore(void *);
-void	usb_first_explore(void *);
 void	usb_create_task_threads(void *);
 void	usb_task_thread(void *);
 struct proc *usb_task_thread_proc = NULL;
@@ -206,7 +205,7 @@ usb_attach(struct device *parent, struct device *self, void *aux)
 #if 1
 		/*
 		 * Turning this code off will delay attachment of USB devices
-		 * until the USB event thread is running, which means that
+		 * until the USB task thread is running, which means that
 		 * the keyboard will not work until after cold boot.
 		 */
 		if (cold && (sc->sc_dev.dv_cfdata->cf_flags & 1))
@@ -225,7 +224,7 @@ usb_attach(struct device *parent, struct device *self, void *aux)
 		if (sc->sc_bus->usbrev == USBREV_2_0)
 			explore_pending++;
 		config_pending_incr();
-		kthread_create_deferred(usb_first_explore, sc);
+		usb_needs_explore(sc->sc_bus->root_hub, 1);
 	}
 }
 
@@ -363,46 +362,6 @@ usb_rem_wait_task(usbd_device_handle dev, struct usb_task *task)
 }
 
 void
-usb_first_explore(void *arg)
-{
-	struct usb_softc *sc = arg;
-	struct timeval now, waited;
-	int pwrdly, waited_ms;
-
-	getmicrouptime(&now);
-	timersub(&now, &sc->sc_ptime, &waited);
-	waited_ms = waited.tv_sec * 1000 + waited.tv_usec / 1000;
-
-	/* Wait for power to come good. */
-	pwrdly = sc->sc_bus->root_hub->hub->hubdesc.bPwrOn2PwrGood * 
-	    UHD_PWRON_FACTOR + USB_EXTRA_POWER_UP_TIME;
-	if (pwrdly > waited_ms)
-		usb_delay_ms(sc->sc_bus, pwrdly - waited_ms);
-
-	/*
-	 * USB1 waits for USB2 to finish their first probe.
-	 * We only really need to have "companion" USB1 controllers
-	 * wait, but it's hard to determine what's a companion and
-	 * what isn't.
-	 */
-	while (sc->sc_bus->usbrev != USBREV_2_0 && explore_pending)
-		(void)tsleep((void *)&explore_pending, PWAIT, "config", 0);
-
-	/*
-	 * Add first explore task to the queue.  The tasks are run in order
-	 * in a single thread, so adding tasks to the queue in the correct
-	 * order means they will run in the correct order.
-	 */
-	usb_needs_explore(sc->sc_bus->root_hub, 1);
-
-	/* Wake up any companions waiting for handover before their probes. */
-	if (sc->sc_bus->usbrev == USBREV_2_0) {
-		explore_pending--;
-		wakeup((void *)&explore_pending);
- 	}
-}
-
-void
 usb_task_thread(void *arg)
 {
 	struct usb_task *task;
@@ -706,6 +665,8 @@ void
 usb_explore(void *v)
 {
 	struct usb_softc *sc = v;
+	struct timeval now, waited;
+	int pwrdly, waited_ms;
 
 	DPRINTFN(2,("%s: %s\n", __func__, sc->sc_dev.dv_xname));
 #ifdef USB_DEBUG
@@ -713,12 +674,41 @@ usb_explore(void *v)
 		return;
 #endif
 
-	if (!sc->sc_bus->dying)
-		sc->sc_bus->root_hub->hub->explore(sc->sc_bus->root_hub);
+	if (sc->sc_bus->dying)
+		return;
+
+	if (sc->sc_bus->flags & USB_BUS_CONFIG_PENDING) {
+		/*
+		 * If this is a low/full speed hub and there is a high
+		 * speed hub that hasn't explored yet, reshedule this
+		 * task, allowing the high speed explore task to run.
+		 */
+		if (sc->sc_bus->usbrev < USBREV_2_0 && explore_pending > 0) {
+			usb_add_task(sc->sc_bus->root_hub,
+			    &sc->sc_explore_task);
+			return;
+		}
+
+		/*
+		 * Wait for power to stabilize.
+		 */
+		getmicrouptime(&now);
+		timersub(&now, &sc->sc_ptime, &waited);
+		waited_ms = waited.tv_sec * 1000 + waited.tv_usec / 1000;
+
+		pwrdly = sc->sc_bus->root_hub->hub->hubdesc.bPwrOn2PwrGood * 
+		    UHD_PWRON_FACTOR + USB_EXTRA_POWER_UP_TIME;
+		if (pwrdly > waited_ms)
+			usb_delay_ms(sc->sc_bus, pwrdly - waited_ms);
+	}
+
+	sc->sc_bus->root_hub->hub->explore(sc->sc_bus->root_hub);
 
 	if (sc->sc_bus->flags & USB_BUS_CONFIG_PENDING) {
 		DPRINTF(("%s: %s: first explore done\n", __func__,
 		    sc->sc_dev.dv_xname));
+		if (sc->sc_bus->usbrev == USBREV_2_0 && explore_pending)
+			explore_pending--;
 		config_pending_decr();
 		sc->sc_bus->flags &= ~(USB_BUS_CONFIG_PENDING);
 	}