9p/xen: fix init sequence

[ Upstream commit 7ef3ae82a6ebbf4750967d1ce43bcdb7e44ff74b ] 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 <[email protected]> Signed-off-by: Alexander Merritt <[email protected]> Signed-off-by: Ariadne Conill <[email protected]> Reviewed-by: Juergen Gross <[email protected]> Message-ID: <[email protected]> Signed-off-by: Dominique Martinet <[email protected]> Signed-off-by: Sasha Levin <[email protected]>
LineageOS · Dec 5, 2024 · c9a1f76 · c9a1f76
1 parent 3947b10
commit c9a1f76
Showing 1 changed file with 5 additions and 2 deletions.
diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
@@ -480,6 +480,7 @@ static int xen_9pfs_front_init(struct xenbus_device *dev)
 		goto error;
 	}
 
+	xenbus_switch_state(dev, XenbusStateInitialised);
 	return 0;
 
  error_xenbus:
@@ -527,8 +528,10 @@ 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: