libusbgx: fix usbgx.service stop / restart

On start the usbgx service configures the usb gadget. However if
one stops the service nothing is done, a subsequent start then
tries to configure the gadget again and fails. `systemctl restart`
is implemented by doing a stop followed by a start and thus is
also affected.

Doing a start/stop/start results with the following reported in
status:

| systemd[1]: Starting Load USB gadget schemas...
| gadget-start[801]: usbg_create_gadget()  duplicate gadget name
| gadget-start[801]:
| gadget-start[801]: Error on import gadget
| gadget-start[801]: Error: USBG_ERROR_EXIST : Already exist
| gadget-start[812]: ls: write error: Device or resource busy

The run-postinsts service does execute a restart for each package
which uses the systemd class which creates a race condition that the
usbgx service is already started when run-postinsts restarts usbgx
and creates the above error output.

Fix that by unconfiguring the usb gadget on stop.

Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/recipes-support/libusbgx/libusbgx/gadget-stop

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+[ -r /etc/default/usbgx ] && . /etc/default/usbgx
+
+for i in $IMPORT_SCHEMAS; do
+    if [ -e /sys/kernel/config/usb_gadget/"$i"/idVendor ]; then
+        if [ -e /sys/kernel/config/usb_gadget/"$i"/idProduct ]; then
+            idVendor=$(cat /sys/kernel/config/usb_gadget/"$i"/idVendor)
+            idProduct=$(cat /sys/kernel/config/usb_gadget/"$i"/idProduct)
+            /usr/bin/gadget-vid-pid-remove ${idVendor}:${idProduct}
+        fi
+    fi
+done

meta-oe/recipes-support/libusbgx/libusbgx/usbgx.service

@@ -5,7 +5,9 @@ After=sys-kernel-config.mount
 
 [Service]
 Type=oneshot
+RemainAfterExit=yes
 ExecStart=/usr/bin/gadget-start
+ExecStop=/usr/bin/gadget-stop
 
 [Install]
 WantedBy=usb-gadget.target

meta-oe/recipes-support/libusbgx/libusbgx_git.bb

@@ -13,6 +13,7 @@ SRC_URI = " \
     file://0001-libusbgx-Add-interface-name-for-NCM-Feature-Descript.patch \
     file://0001-fix-stack-buffer-overflow-in-usbg_f_foo_attr_val-pro.patch \
     file://gadget-start \
+    file://gadget-stop \
     file://usbgx.initd \
     file://usbgx.service \
 "
@@ -39,6 +40,8 @@ INHIBIT_UPDATERCD_BBCLASS = "${@bb.utils.contains('PACKAGECONFIG', 'examples', '
 do_install:append() {
     install -Dm 0755 ${WORKDIR}/gadget-start ${D}${bindir}/gadget-start
     sed -i -e 's,/usr/bin,${bindir},g' -e 's,/etc,${sysconfdir},g' ${D}${bindir}/gadget-start
+    install -m 0755 ${WORKDIR}/gadget-start ${D}${bindir}/gadget-stop
+    sed -i -e 's,/usr/bin,${bindir},g' -e 's,/etc,${sysconfdir},g' ${D}${bindir}/gadget-stop
 
     if ${@bb.utils.contains('DISTRO_FEATURES','systemd','true','false',d)}; then
         install -Dm 0644 ${WORKDIR}/usbgx.service ${D}${systemd_system_unitdir}/usbgx.service