core: update comment

unit_serialize_item() was dropped in d68c645bd3323ae1f0dfcb8fd74ea6b19681db8a.
But "cannot be restored from other sources" is also not entirely true: for
example for mounts we may be able to figure out most state from /p/s/mountinfo.
So let's make the comment more oblique.

diff --git a/src/core/unit.h b/src/core/unit.h
index d34d647845e1035e7e024000604a5a573a1e4390..2db40e51e852a94a8e487f087cf723dec68184fb 100644 (file)
--- a/src/core/unit.h
+++ b/src/core/unit.h
@@ -543,8 +543,8 @@ typedef struct UnitVTable {
 
         bool (*can_reload)(Unit *u);
 
-        /* Write all data that cannot be restored from other sources
-         * away using unit_serialize_item() */
+        /* Serialize state and file descriptors that should be carried over into the new
+         * instance after reexecution. */
         int (*serialize)(Unit *u, FILE *f, FDSet *fds);
 
         /* Restore one item from the serialization */