9p/xen: fix init sequence

Large amount of mount hangs observed during hotplugging of 9pfs devices. The
9pfs Xen driver attempts to initialize itself more than once, causing the
frontend and backend to disagree: the backend listens on a channel that the
frontend does not send on, resulting in stalled processing.

Only allow initialization of 9p frontend once.

Fixes: c15fe55d14b3b ("9p/xen: fix connection sequence")
Signed-off-by: Alex Zenla <alex@edera.dev>
Signed-off-by: Alexander Merritt <alexander@edera.dev>
Signed-off-by: Ariadne Conill <ariadne@ariadne.space>
Reviewed-by: Juergen Gross <jgross@suse.com>
Message-ID: <20241119211633.38321-1-alexander@edera.dev>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>

diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
index dfdbe1ca533872ce189e64ff5f4a083c5261ddee..0304e8a1616d89d57898cda371b05dad1f034322 100644 (file)
--- a/net/9p/trans_xen.c
+++ b/net/9p/trans_xen.c
@@ -465,6 +465,7 @@ static int xen_9pfs_front_init(struct xenbus_device *dev)
                goto error;
        }
 
+       xenbus_switch_state(dev, XenbusStateInitialised);
        return 0;
 
  error_xenbus:
@@ -512,8 +513,10 @@ static void xen_9pfs_front_changed(struct xenbus_device *dev,
                break;
 
        case XenbusStateInitWait:
-               if (!xen_9pfs_front_init(dev))
-                       xenbus_switch_state(dev, XenbusStateInitialised);
+               if (dev->state != XenbusStateInitialising)
+                       break;
+
+               xen_9pfs_front_init(dev);
                break;
 
        case XenbusStateConnected: