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, 14 insertions, 4 deletions

diff --git a/libports/transfer-right.c b/libports/transfer-right.c
index 72488a99..3f482905 100644
--- a/libports/transfer-right.c
+++ b/libports/transfer-right.c
@@ -41,7 +41,10 @@ ports_transfer_right (void *tostruct,
   port = frompi->port_right;
   if (port != MACH_PORT_NULL)
     {
+      pthread_rwlock_wrlock (&_ports_htable_lock);
+      hurd_ihash_locp_remove (&_ports_htable, frompi->ports_htable_entry);
       hurd_ihash_locp_remove (&frompi->bucket->htable, frompi->hentry);
+      pthread_rwlock_unlock (&_ports_htable_lock);
       frompi->port_right = MACH_PORT_NULL;
       if (frompi->flags & PORT_HAS_SENDRIGHTS)
 	{
@@ -54,7 +57,10 @@ ports_transfer_right (void *tostruct,
   /* Destroy the existing right in TOPI. */
   if (topi->port_right != MACH_PORT_NULL)
     {
+      pthread_rwlock_wrlock (&_ports_htable_lock);
+      hurd_ihash_locp_remove (&_ports_htable, topi->ports_htable_entry);
       hurd_ihash_locp_remove (&topi->bucket->htable, topi->hentry);
+      pthread_rwlock_unlock (&_ports_htable_lock);
       err = mach_port_mod_refs (mach_task_self (), topi->port_right,
 				MACH_PORT_RIGHT_RECEIVE, -1);
       assert_perror (err);
@@ -74,10 +80,16 @@ ports_transfer_right (void *tostruct,
   topi->port_right = port;
   topi->cancel_threshold = frompi->cancel_threshold;
   topi->mscount = frompi->mscount;
-  
+
+  pthread_mutex_unlock (&_ports_lock);
+
   if (port)
     {
+      pthread_rwlock_wrlock (&_ports_htable_lock);
+      err = hurd_ihash_add (&_ports_htable, port, topi);
+      assert_perror (err);
       err = hurd_ihash_add (&topi->bucket->htable, port, topi);
+      pthread_rwlock_unlock (&_ports_htable_lock);
       assert_perror (err);
       if (topi->bucket != frompi->bucket)
         {
@@ -86,9 +98,7 @@ ports_transfer_right (void *tostruct,
 	  assert_perror (err);
 	}
     }
-  
-  pthread_mutex_unlock (&_ports_lock);
-  
+
   /* Take care of any lowered reference counts. */
   if (dereffrompi)
     ports_port_deref (frompi);