/*
* Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
*
- * @APPLE_LICENSE_HEADER_START@
- *
- * The contents of this file constitute Original Code as defined in and
- * are subject to the Apple Public Source License Version 1.1 (the
- * "License"). You may not use this file except in compliance with the
- * License. Please obtain a copy of the License at
- * http://www.apple.com/publicsource and read it before using this file.
- *
- * This Original Code and all software distributed under the License are
- * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.
+ *
+ * Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
- * License for the specific language governing rights and limitations
- * under the License.
- *
- * @APPLE_LICENSE_HEADER_END@
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
/*
* @OSF_COPYRIGHT@
- *
+ *
*/
#include <kern/sync_sema.h>
#include <ipc/port.h>
#include <ipc/ipc_space.h>
#include <ipc/ipc_port.h>
+#include <mach/mach_types.h>
#include <mach/semaphore.h>
#include <mach/lock_set_server.h>
#include <mach/mach_port_server.h>
#include <mach/port.h>
+/*
+ * Routine: port_name_to_semaphore
+ * Purpose:
+ * Convert from a port name in the current space to a semaphore.
+ * Produces a semaphore ref, which may be null.
+ * Conditions:
+ * Nothing locked.
+ */
kern_return_t
port_name_to_semaphore(
- mach_port_name_t name,
- semaphore_t *semaphorep)
+ mach_port_name_t name,
+ semaphore_t *semaphorep)
{
- semaphore_t semaphore;
ipc_port_t kern_port;
kern_return_t kr;
*semaphorep = SEMAPHORE_NULL;
return KERN_INVALID_NAME;
}
-
+
kr = ipc_object_translate(current_space(), name, MACH_PORT_RIGHT_SEND,
- (ipc_object_t *) &kern_port);
+ (ipc_object_t *) &kern_port);
if (kr != KERN_SUCCESS) {
*semaphorep = SEMAPHORE_NULL;
return kr;
/* have the port locked */
assert(IP_VALID(kern_port));
- if (!ip_active(kern_port) || (ip_kotype(kern_port) != IKOT_SEMAPHORE)) {
- ip_unlock(kern_port);
- *semaphorep = SEMAPHORE_NULL;
- return KERN_INVALID_ARGUMENT;
+ *semaphorep = convert_port_to_semaphore(kern_port);
+ if (*semaphorep == SEMAPHORE_NULL) {
+ /* the port is valid, but doesn't denote a semaphore */
+ kr = KERN_INVALID_CAPABILITY;
+ } else {
+ kr = KERN_SUCCESS;
}
-
- semaphore = (semaphore_t) kern_port->ip_kobject;
- assert(semaphore != SEMAPHORE_NULL);
- semaphore_reference(semaphore);
ip_unlock(kern_port);
- *semaphorep = semaphore;
- return KERN_SUCCESS;
+ return kr;
}
-
+
+/*
+ * Routine: convert_port_to_semaphore
+ * Purpose:
+ * Convert from a port to a semaphore.
+ * Doesn't consume the port [send-right] ref;
+ * produces a semaphore ref, which may be null.
+ * Conditions:
+ * Caller has a send-right reference to port.
+ * Port may or may not be locked.
+ */
semaphore_t
-convert_port_to_semaphore (ipc_port_t port)
+convert_port_to_semaphore(ipc_port_t port)
{
- semaphore_t semaphore = SEMAPHORE_NULL;
-
- if (IP_VALID (port)) {
- ip_lock(port);
- if (ip_active(port) && (ip_kotype(port) == IKOT_SEMAPHORE)) {
+ if (IP_VALID(port)) {
+ semaphore_t semaphore;
+
+ /*
+ * No need to lock because we have a reference on the
+ * port, and if it is a true semaphore port, that reference
+ * keeps the semaphore bound to the port (and active).
+ */
+ if (ip_kotype(port) == IKOT_SEMAPHORE) {
+ assert(ip_active(port));
semaphore = (semaphore_t) port->ip_kobject;
semaphore_reference(semaphore);
+ return semaphore;
}
- ip_unlock(port);
}
-
- return (semaphore);
+ return SEMAPHORE_NULL;
}
+/*
+ * Routine: convert_semaphore_to_port
+ * Purpose:
+ * Convert a semaphore reference to a send right to a
+ * semaphore port.
+ *
+ * Consumes the semaphore reference. If the semaphore
+ * port currently has no send rights (or doesn't exist
+ * yet), the reference is donated to the port to represent
+ * all extant send rights collectively.
+ */
ipc_port_t
-convert_semaphore_to_port (semaphore_t semaphore)
+convert_semaphore_to_port(semaphore_t semaphore)
{
- ipc_port_t port;
+ ipc_port_t port, send;
- if (semaphore != SEMAPHORE_NULL)
- port = ipc_port_make_send(semaphore->port);
- else
- port = IP_NULL;
+ if (semaphore == SEMAPHORE_NULL) {
+ return IP_NULL;
+ }
- return (port);
-}
+ /* caller is donating a reference */
+ port = semaphore->port;
-lock_set_t
-convert_port_to_lock_set (ipc_port_t port)
-{
- lock_set_t lock_set = LOCK_SET_NULL;
+ if (!IP_VALID(port)) {
+ port = ipc_port_alloc_kernel();
+ assert(IP_VALID(port));
+ ipc_kobject_set_atomically(port, (ipc_kobject_t) semaphore, IKOT_SEMAPHORE);
- if (IP_VALID (port)) {
- ip_lock(port);
- if (ip_active(port) && (ip_kotype(port) == IKOT_LOCK_SET)) {
- lock_set = (lock_set_t) port->ip_kobject;
- lock_set_reference(lock_set);
+ /* If we lose the race, deallocate and pick up the other guy's port */
+ if (!OSCompareAndSwapPtr(IP_NULL, port, &semaphore->port)) {
+ ipc_port_dealloc_kernel(port);
+ port = semaphore->port;
+ assert(ip_kotype(port) == IKOT_SEMAPHORE);
+ assert(port->ip_kobject == (ipc_kobject_t)semaphore);
}
- ip_unlock(port);
}
- return (lock_set);
+ ip_lock(port);
+ assert(ip_active(port));
+ send = ipc_port_make_send_locked(port);
+
+ if (1 == port->ip_srights) {
+ ipc_port_t old_notify;
+
+ /* transfer our ref to the port, and arm the no-senders notification */
+ assert(IP_NULL == port->ip_nsrequest);
+ ipc_port_nsrequest(port, port->ip_mscount, ipc_port_make_sonce_locked(port), &old_notify);
+ /* port unlocked */
+ assert(IP_NULL == old_notify);
+ } else {
+ /* piggyback on the existing port reference, so consume ours */
+ ip_unlock(port);
+ semaphore_dereference(semaphore);
+ }
+ return send;
}
-ipc_port_t
-convert_lock_set_to_port (lock_set_t lock_set)
+/*
+ * Routine: semaphore_notify
+ * Purpose:
+ * Called whenever the Mach port system detects no-senders
+ * on the semaphore port.
+ *
+ * When a send-right is first created, a no-senders
+ * notification is armed (and a semaphore reference is donated).
+ *
+ * A no-senders notification will be posted when no one else holds a
+ * send-right (reference) to the semaphore's port. This notification function
+ * will consume the semaphore reference donated to the extant collection of
+ * send-rights.
+ */
+void
+semaphore_notify(mach_msg_header_t *msg)
{
- ipc_port_t port;
+ mach_no_senders_notification_t *notification = (void *)msg;
+ ipc_port_t port = notification->not_header.msgh_remote_port;
+ semaphore_t semaphore;
- if (lock_set != LOCK_SET_NULL)
- port = ipc_port_make_send(lock_set->port);
- else
- port = IP_NULL;
+ assert(ip_active(port));
+ assert(IKOT_SEMAPHORE == ip_kotype(port));
+ semaphore = (semaphore_t)port->ip_kobject;
+
+ semaphore_dereference(semaphore);
+}
- return (port);
+lock_set_t
+convert_port_to_lock_set(__unused ipc_port_t port)
+{
+ return LOCK_SET_NULL;
}
+ipc_port_t
+convert_lock_set_to_port(__unused lock_set_t lock_set)
+{
+ return IP_NULL;
+}
projects / apple / xnu.git / blobdiff