Subject: [PATCH] Keep retained shared listeners linked during interface GC

release_listener() can retain a listener by transferring its iface
pointer to another interface record which uses the same address. In that
case it returns zero, but enumerate_interfaces() does not advance the
pointer-to-pointer cursor.

If the next listener is removed, updating the stale cursor unlinks the
retained listener as well. Advance the cursor when release_listener()
retains a shared listener, just as when the original iface remains found.

This is independent of the larger interface-snapshot transaction change.
The existing shared-listener regression in the snapshot test harness
covers preservation of the list link, iface ownership and socket inode.

Base-commit: a9880c595f052d63859d6ed8aa86a3a6b007bf20

---
 src/network.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/network.c b/src/network.c
index 6c4469dcb0e9c2e72a5874bbd8d69c630d966924..aa3ef89e714169dd523c567ddd331d217afb9fce 100644
--- a/src/network.c
+++ b/src/network.c
@@ -868,6 +868,8 @@ again:
 	      *up = tmp;
 	      freed = 1;
 	    }
+          else
+            up = &l->next;
 	}
 
       if (freed)