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From: Weongyo Jeong <weongyo@FreeBSD.org>
Date: Sun, 12 Sep 2010 00:53:10 +0000 (UTC)
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Subject: svn commit: r212489 - user/weongyo/usb/sys/dev/usb/controller
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Author: weongyo
Date: Sun Sep 12 00:53:10 2010
New Revision: 212489
URL: http://svn.freebsd.org/changeset/base/212489

Log:
  Adds a comment why the thread count should be 1.

Modified:
  user/weongyo/usb/sys/dev/usb/controller/usb_controller.c

Modified: user/weongyo/usb/sys/dev/usb/controller/usb_controller.c
==============================================================================
--- user/weongyo/usb/sys/dev/usb/controller/usb_controller.c	Sun Sep 12 00:49:16 2010	(r212488)
+++ user/weongyo/usb/sys/dev/usb/controller/usb_controller.c	Sun Sep 12 00:53:10 2010	(r212489)
@@ -402,6 +402,10 @@ usb_attach_sub(device_t dev, struct usb_
 	/* Initialise USB explore taskqueue and tasks */
 	bus->explore_tq = taskqueue_create("usb_explore_taskq", M_WAITOK,
 	    taskqueue_thread_enqueue, &bus->explore_tq);
+	/*
+	 * NOTE: the thread count always should be 1.  If more, it couldn't
+	 * guarantee the serialization between attach, detach and explore.
+	 */
 	taskqueue_start_threads(&bus->explore_tq, 1, USB_PRI_MED,
 	    "USB explore taskq");
 	TASK_INIT(&bus->attach_task, 0, usb_bus_attach, bus);