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From: Andrew Thompson <thompsa@FreeBSD.org>
Date: Sat, 29 Aug 2009 15:42:06 +0000 (UTC)
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Subject: svn commit: r196642 - in stable/8/sys: . amd64/include/xen
	cddl/contrib/opensolaris contrib/dev/acpica contrib/pf
	dev/usb dev/xen/xenpci
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Author: thompsa
Date: Sat Aug 29 15:42:06 2009
New Revision: 196642
URL: http://svn.freebsd.org/changeset/base/196642

Log:
  MFC r196547
  
   It is possible for all the kthreads to exit (hci modules unloaded) which in
   turn ends our usb process. This means the proc pointer becomes invalid and will
   panic if a new kthread is added. Count the number of threads and clear the proc
   pointer on the last one.
  
  Approved by:	re (kib)

Modified:
  stable/8/sys/   (props changed)
  stable/8/sys/amd64/include/xen/   (props changed)
  stable/8/sys/cddl/contrib/opensolaris/   (props changed)
  stable/8/sys/contrib/dev/acpica/   (props changed)
  stable/8/sys/contrib/pf/   (props changed)
  stable/8/sys/dev/usb/usb_process.c
  stable/8/sys/dev/xen/xenpci/   (props changed)

Modified: stable/8/sys/dev/usb/usb_process.c
==============================================================================
--- stable/8/sys/dev/usb/usb_process.c	Sat Aug 29 15:21:50 2009	(r196641)
+++ stable/8/sys/dev/usb/usb_process.c	Sat Aug 29 15:42:06 2009	(r196642)
@@ -64,6 +64,7 @@
 
 #if (__FreeBSD_version >= 800000)
 static struct proc *usbproc;
+static int usb_pcount;
 #define	USB_THREAD_CREATE(f, s, p, ...) \
 		kproc_kthread_add((f), (s), &usbproc, (p), RFHIGHPID, \
 		    0, "usb", __VA_ARGS__)
@@ -183,6 +184,11 @@ usb_process(void *arg)
 	up->up_ptr = NULL;
 	cv_signal(&up->up_cv);
 	mtx_unlock(up->up_mtx);
+#if (__FreeBSD_version >= 800000)
+	/* Clear the proc pointer if this is the last thread. */
+	if (--usb_pcount == 0)
+		usbproc = NULL;
+#endif
 
 	USB_THREAD_EXIT(0);
 }
@@ -218,6 +224,9 @@ usb_proc_create(struct usb_process *up, 
 		up->up_ptr = NULL;
 		goto error;
 	}
+#if (__FreeBSD_version >= 800000)
+	usb_pcount++;
+#endif
 	return (0);
 
 error: