From 888a09bbb454a6d5020219d64ff272402c890111 Mon Sep 17 00:00:00 2001
From: hselasky <hselasky@ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f>
Date: Sat, 31 Dec 2011 14:24:22 +0000
Subject: [PATCH] MFC r228758: Fix for race against user-space applications
 trying to change the configuration on USB HUBs.

PR:		kern/163091


git-svn-id: svn://svn.freebsd.org/base/stable/9@229097 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
---
 sys/dev/usb/usb_hub.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/sys/dev/usb/usb_hub.c b/sys/dev/usb/usb_hub.c
index 5795d56bf..f48e5058c 100644
--- a/sys/dev/usb/usb_hub.c
+++ b/sys/dev/usb/usb_hub.c
@@ -707,6 +707,13 @@ uhub_explore(struct usb_device *udev)
 		DPRINTF("Device is suspended!\n");
 		return (0);
 	}
+
+	/*
+	 * Make sure we don't race against user-space applications
+	 * like LibUSB:
+	 */
+	usbd_enum_lock(udev);
+
 	for (x = 0; x != hub->nports; x++) {
 		up = hub->ports + x;
 		portno = x + 1;
@@ -784,6 +791,8 @@ uhub_explore(struct usb_device *udev)
 		up->restartcnt = 0;
 	}
 
+	usbd_enum_unlock(udev);
+
 	/* initial status checked */
 	sc->sc_flags |= UHUB_FLAG_DID_EXPLORE;
 
-- 
2.45.0