libports: lock-less reference counting for port_info objects

* libports/ports.h (struct port_info): Use the new type.
* libports/lookup-port.c: No need to lock _ports_lock anymore.
* libports/bucket-iterate.c: Likewise.
* libports/complete-deallocate.c: Check if someone reacquired a
reference through a hash table lookup.
* libports/create-internal.c: Use the new reference counting primitives.
* libports/get-right.c: Likewise.
* libports/import-port.c: Likewise.
* libports/port-deref-weak.c: Likewise.
* libports/port-deref.c: Likewise.
* libports/port-ref-weak.c: Likewise.
* libports/port-ref.c: Likewise.
* libports/reallocate-from-external.c: Likewise.
* libports/transfer-right.c: Likewise.
* utils/rpctrace.c: Likewise.

1 files changed, 14 insertions, 0 deletions

diff --git a/libports/complete-deallocate.c b/libports/complete-deallocate.c
index 4768dab9..0d852f57 100644
--- a/libports/complete-deallocate.c
+++ b/libports/complete-deallocate.c
@@ -29,15 +29,29 @@ _ports_complete_deallocate (struct port_info *pi)
 
   if (pi->port_right)
     {
+      struct references result;
+
       pthread_rwlock_wrlock (&_ports_htable_lock);
+      refcounts_references (&pi->refcounts, &result);
+      if (result.hard > 0 || result.weak > 0)
+        {
+          /* A reference was reacquired through a hash table lookup.
+             It's fine, we didn't touch anything yet. */
+          pthread_mutex_unlock (&_ports_htable_lock);
+          return;
+        }
+
       hurd_ihash_locp_remove (&_ports_htable, pi->ports_htable_entry);
       hurd_ihash_locp_remove (&pi->bucket->htable, pi->hentry);
       pthread_rwlock_unlock (&_ports_htable_lock);
+
       mach_port_mod_refs (mach_task_self (), pi->port_right,
 			  MACH_PORT_RIGHT_RECEIVE, -1);
       pi->port_right = MACH_PORT_NULL;
     }
 
+  pthread_mutex_lock (&_ports_lock);
+
   pi->bucket->count--;
   pi->class->count--;