port leak when starting a translator

[Samuel Thibault]

Hello,

I've noticed a port leak on buildds when starting a translator. The
backtrace of the port allocation is this:

_ports_create_port_internal
ports_create_port_noinstall
diskfs_start_protid
diskfs_create_protid
diskfs_S_dir_lookup (libdiskfs/dir-lookup.c:260)
_Xdir_lookup

What I understand from the diskfs_S_dir_lookup code with my poor
libports knowledge:
- diskfs_make_peropen (dnp, 0, dircred->po, &newpo) creates a peropen
  structure "newpo". Its reference counter is initialized to 0.
- diskfs_create_portid(newpo, user, &newpi) creates a libport port with receive 
right. Its
  reference count is initialized to 1. newpo is made to reference it,
  its reference counter gets increased to 1. The port right is added to
  the diskfs_port_bucket portset.
- dirport = ports_get_send_right(newpi) adds a port send right to newpi, whose
  reference counter gets increased to 2.
- ports_port_deref(newpi) drops a reference, the counter thus gets back
  to 1. As I understand it, it's supposed to be the send one.
- newpi=0 forgets about the receive part of newpi, only the send part
  dirport remains.
- dirport is given to fshelp_fetch_root(), which copies its send right
  only.
- mach_port_deallocate (mach_task_self(), dirport); release a send
  right.

I'm unsure how the receive part of the kernel port in newpi port is
supposed to get deallocated in that scenario, I guess the send right
release at the end is supposed to trigger NOTIFY_NO_SENDERS, and
libports handles deallocation from that?  The thing is that it doesn't
seem to happen, thus leaving a port leak here.

Any idea?

Samuel, who wishes he knew about all that port stuff a lot more...