From: Roger Pau Monné <roger.pau@citrix.com>
Date: Wed, 16 Feb 2022 14:52:22 +0000 (+0100)
Subject: libxl: force netback to wait for hotplug execution before connecting
X-Git-Tag: archive/raspbian/4.16.0+51-g0941d6cb-1+rpi1~2^2~26^2~3
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=58d289c90690841def25b451d3855a187781b3ab;p=xen.git

libxl: force netback to wait for hotplug execution before connecting

By writing an empty "hotplug-status" xenstore node in the backend path
libxl can force Linux netback to wait for hotplug script execution
before proceeding to the 'connected' state.

This is required so that netback doesn't skip state 2 (InitWait) and
thus blocks libxl waiting for such state in order to launch the
hotplug script (see libxl__wait_device_connection).

Reported-by: James Dingwall <james-xen@dingwall.me.uk>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Tested-by: James Dingwall <james-xen@dingwall.me.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Tested-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
master commit: 0bdc43c8dec993258e930b34855853c22b917519
master date: 2022-01-27 13:51:19 +0100
---

diff --git a/tools/libs/light/libxl_nic.c b/tools/libs/light/libxl_nic.c
index 0b45469dca..0b9e70c9d1 100644
--- a/tools/libs/light/libxl_nic.c
+++ b/tools/libs/light/libxl_nic.c
@@ -248,6 +248,13 @@ static int libxl__set_xenstore_nic(libxl__gc *gc, uint32_t domid,
     flexarray_append(ro_front, "mtu");
     flexarray_append(ro_front, GCSPRINTF("%u", nic->mtu));
 
+    /*
+     * Force backend to wait for hotplug script execution before switching to
+     * connected state.
+     */
+    flexarray_append(back, "hotplug-status");
+    flexarray_append(back, "");
+
     return 0;
 }