In my fs_filter component (much like the vfs server), I am trying to allow multiple clients fast, non-blocking access to multiple filesystems. To do this without several threads, my component needs to know when each filesystem server unblocks so it can send more packets. Unfortunately, the File_system::Client interface (which File_system::Connection inherits) doesn't provide a way to receive signals when the server acknowledges packets or is ready for more packets, given that it only provides a Session:Tx::Source object for accessing the packet stream. The Session::Tx::Source interface provide the methods sigh_ack_avail() and sigh_ready_to_submit(), which allow a cilent to get the signal handlers currently in use, but doesn't allow registering new signal handlers. I added a workaround that exposes the Packet_stream_tx::Client object to the client, but it would be good to have a better way to register these signal handlers. Is there currently a way to do this, or does this require a modification to the API, like what I did?