Detach all devices before suspending

Host controller drivers are detached on suspend, so all devices will be
detached anyway. Do it before any domain is actually suspended to avoid
deadlock.

Fixes QubesOS/qubes-issues#4657

Makefile

@@ -5,6 +5,9 @@ install-vm:
 	install qubes-rpc/qubes.USB $(DESTDIR)/etc/qubes-rpc
 	install -d $(DESTDIR)/usr/lib/qubes
 	install src/usb-* $(DESTDIR)/usr/lib/qubes
+	install -d $(DESTDIR)/etc/qubes/suspend-pre.d
+	ln -s ../../../usr/lib/qubes/usb-detach-all \
+		$(DESTDIR)/etc/qubes/suspend-pre.d/usb-detach-all.sh
 
 PYTHON2_SITELIB ?= $(shell python2 -c "from distutils.sysconfig import get_python_lib; print get_python_lib(0)")
 

rpm_spec/qubes-usb-proxy.spec.in

@@ -24,12 +24,13 @@ make install-vm DESTDIR=${RPM_BUILD_ROOT}
 
 %files
 #%%doc
-/usr/lib/qubes/usb-import
 /etc/qubes-rpc/qubes.USB
 /etc/qubes-rpc/qubes.USBAttach
 /etc/qubes-rpc/qubes.USBDetach
+/etc/qubes/suspend-pre.d/usb-detach-all.sh
 /usr/lib/qubes/usb-import
 /usr/lib/qubes/usb-export
+/usr/lib/qubes/usb-detach-all
 
 %changelog
 @CHANGELOG@

src/usb-detach-all

@@ -0,0 +1,9 @@
+#!/bin/sh
+
+# Detach all devices before suspend
+
+for dev in /sys/bus/usb/devices/*/usbip_sockfd; do
+    if [ -w "$dev" ]; then
+        echo -1 > "$dev"
+    fi
+done