libports: use a global hash table for the lookups

Previously, libports used a hash table per port bucket.  This makes
looking up a port difficult if one does not know the port bucket, as
one has to iterate over all buckets and do a hash table lookup each.

Having to iterate over the buckets makes it necessary to keep a list
of all buckets, which has to be updated and protected by a lock as
well.

Also, the current code in _ports_bucket_class_iterate iterates over
the hash table associated with the bucket given.  When
ports_class_iterate calls this common function, it obtains a reference
to the bucket from one of the ports in the given class.  This will not
work if a class contains ports in different port buckets.  This
limitation is not documented as far as I can see.  Again, having to
maintain this list has its cost and requires serialization.

Use a global hash table for lookups instead.  Keep the per-bucket hash
tables for efficient iteration over buckets.  Furthermore, serialize
access to all hash tables using a separate lock.  Remove the linked
lists of all buckets and all ports in a class.

* libports/bucket-iterate.c (ports_bucket_iterate): Acquire
_ports_htable_lock.  Also, generalize ports_bucket_iterate so that it
takes a pointer to a hash table as first argument.
(ports_bucket_iterate): Ajust call to former function accordingly.
* libports/class-iterate.c (ports_class_iterate): Just call the
generalized _ports_bucket_class_iterate with the global hash table as
argument.
* libports/ports.h (struct port_info): Remove the port class links.
(struct port_bucket): Remove the hash table, and the all buckets link.
(_ports_all_buckets): Remove declaration.
(_ports_htable): New global hash table.
(_ports_htable_lock): Protected by this lock.
* libports/claim-right.c: Adjust accordingly.
* libports/complete-deallocate.c: Likewise.
* libports/create-bucket.c: Likewise.
* libports/create-class.c: Likewise.
* libports/create-internal.c: Likewise.
* libports/destroy-right.c: Likewise.
* libports/import-port.c: Likewise.
* libports/lookup-port.c: Likewise.
* libports/reallocate-from-external.c: Likewise.
* libports/reallocate-port.c: Likewise.
* libports/transfer-right.c: Likewise.
* libports/inhibit-all-rpcs.c: Iterate over the hash table.
* libports/inhibit-bucket-rpcs.c: Likewise, but filter using bucket.
* libports/inhibit-class-rpcs.c: Likewise, but filter using class.
* libports/init.c (_ports_htable): Initialize.
(_ports_htable_lock): Likewise.

1 files changed, 9 insertions, 14 deletions

diff --git a/libports/lookup-port.c b/libports/lookup-port.c
index f79f6f0c..858ee112 100644
--- a/libports/lookup-port.c
+++ b/libports/lookup-port.c
@@ -26,27 +26,22 @@ ports_lookup_port (struct port_bucket *bucket,
 		   mach_port_t port,
 		   struct port_class *class)
 {
-  struct port_info *pi = 0;
-  
+  struct port_info *pi;
+
   pthread_mutex_lock (&_ports_lock);
+  pthread_rwlock_rdlock (&_ports_htable_lock);
 
-  if (bucket)
-    pi = hurd_ihash_find (&bucket->htable, port);
-  else
-    for (bucket = _ports_all_buckets; bucket; bucket = bucket->next)
-      {
-	pi = hurd_ihash_find (&bucket->htable, port);
-	if (pi)
-	  break;
-      }
-  
-  if (pi && class && pi->class != class)
+  pi = hurd_ihash_find (&_ports_htable, port);
+  if (pi
+      && ((class && pi->class != class)
+          || (bucket && pi->bucket != bucket)))
     pi = 0;
 
   if (pi)
     pi->refcnt++;
 
+  pthread_rwlock_unlock (&_ports_htable_lock);
   pthread_mutex_unlock (&_ports_lock);
-  
+
   return pi;
 }