linux-kernel - [PATCH 5.10 60/79] xen-netback: only remove hotplug-status when the vif is actually destroyed

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Date:   Tue, 13 Sep 2022 16:05:05 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Paul Durrant <pdurrant@...zon.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 60/79] xen-netback: only remove hotplug-status when the vif is actually destroyed

From: Paul Durrant <pdurrant@...zon.com>

[ Upstream commit c55f34b6aec2a8cb47eadaffea773e83bf85de91 ]

Removing 'hotplug-status' in backend_disconnected() means that it will be
removed even in the case that the frontend unilaterally disconnects (which
it is free to do at any time). The consequence of this is that, when the
frontend attempts to re-connect, the backend gets stuck in 'InitWait'
rather than moving straight to 'Connected' (which it can do because the
hotplug script has already run).
Instead, the 'hotplug-status' mode should be removed in netback_remove()
i.e. when the vif really is going away.

Fixes: 0f4558ae9187 ("Revert "xen-netback: remove 'hotplug-status' once it has served its purpose"")
Signed-off-by: Paul Durrant <pdurrant@...zon.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/xen-netback/xenbus.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index ca261e0fc9c9b..9ee9ce0493fe6 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -256,7 +256,6 @@ static void backend_disconnect(struct backend_info *be)
 		unsigned int queue_index;
 
 		xen_unregister_watchers(vif);
-		xenbus_rm(XBT_NIL, be->dev->nodename, "hotplug-status");
 #ifdef CONFIG_DEBUG_FS
 		xenvif_debugfs_delif(vif);
 #endif /* CONFIG_DEBUG_FS */
@@ -984,6 +983,7 @@ static int netback_remove(struct xenbus_device *dev)
 	struct backend_info *be = dev_get_drvdata(&dev->dev);
 
 	unregister_hotplug_status_watch(be);
+	xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
 	if (be->vif) {
 		kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
 		backend_disconnect(be);
-- 
2.35.1