Index: sys/dev/usb/usbdi.h
===================================================================
RCS file: /cvsroot/src/sys/dev/usb/usbdi.h,v
retrieving revision 1.87
diff -u -p -u -r1.87 usbdi.h
--- sys/dev/usb/usbdi.h	22 Jan 2013 13:27:59 -0000	1.87
+++ sys/dev/usb/usbdi.h	4 Sep 2013 12:57:02 -0000
@@ -278,9 +278,19 @@ struct usbif_attach_arg {
 /* No match */
 #define UMATCH_NONE					 0
 
+
+/*
+ * IPL_USB is defined as IPL_VM for drivers that have not been made MP safe.
+ * IPL_VM (currently) takes the kernel lock.
+ *
+ * Any driver converted to be MP safe should switch to IPL_SCHED and remove
+ * the need for the kernel lock to be taken.
+ *
+ * Eventually, IPL_USB can/should be changed
+ */
 #define splusb splsoftnet
-#define splhardusb splbio
-#define IPL_USB IPL_BIO
+#define splhardusb splvm
 #define IPL_SOFTUSB IPL_SOFTNET
+#define IPL_USB IPL_VM
 
 #endif /* _USBDI_H_ */
Index: sys/dev/usb/usbdivar.h
===================================================================
RCS file: /cvsroot/src/sys/dev/usb/usbdivar.h,v
retrieving revision 1.103
diff -u -p -u -r1.103 usbdivar.h
--- sys/dev/usb/usbdivar.h	24 Mar 2013 22:38:45 -0000	1.103
+++ sys/dev/usb/usbdivar.h	4 Sep 2013 12:57:02 -0000
@@ -33,7 +33,7 @@
 /*
  * Discussion about locking in the USB code:
  *
- * The host controller presents one lock at IPL_SOFTUSB.
+ * The host controller presents one lock at IPL_SOFTUSB (aka IPL_SOFTNET).
  *
  * List of hardware interface methods, and whether the lock is held
  * when each is called by this module: