xref: /xnu-8796.101.5/bsd/net/init.c (revision aca3beaa3dfbd42498b42c5e5ce20a938e6554e5)

/*
 * Copyright (c) 2000-2021 Apple Computer, Inc. All rights reserved.
 *
 * @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, 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@
 */

#include <kern/kalloc.h>
#include <libkern/OSAtomic.h>
#include <sys/errno.h>
#include <net/init.h>
#include <libkern/libkern.h>
#include <string.h>

struct init_list_entry {
	struct init_list_entry  *next;
	net_init_func_ptr               func;
};

#define LIST_RAN ((struct init_list_entry*)0xffffffff)
static struct init_list_entry   *list_head = 0;

errno_t
net_init_add(
	net_init_func_ptr init_func)
{
	struct init_list_entry  *entry;

	if (init_func == 0) {
		return EINVAL;
	}

	/* Check if we've already started */
	if (list_head == LIST_RAN) {
		return EALREADY;
	}

	entry = kalloc_type(struct init_list_entry,
	    Z_WAITOK | Z_ZERO | Z_NOFAIL);

	entry->func = init_func;

	do {
		entry->next = list_head;

		if (entry->next == LIST_RAN) {
			/* List already ran, cleanup and call the function */
			kfree_type(struct init_list_entry, entry);
			return EALREADY;
		}
	} while (!OSCompareAndSwapPtr(entry->next, entry, &list_head));

	return 0;
}

__private_extern__ void
net_init_run(void)
{
	struct init_list_entry  *backward_head = 0;
	struct init_list_entry  *forward_head = 0;
	struct init_list_entry  *current = 0;

	/*
	 * Grab the list, replacing the head with 0xffffffff to indicate
	 * that we've already run.
	 */
	do {
		backward_head = list_head;
	} while (!OSCompareAndSwapPtr(backward_head, LIST_RAN, &list_head));

	/* Reverse the order of the list */
	while (backward_head != 0) {
		current = backward_head;
		backward_head = current->next;
		current->next = forward_head;
		forward_head = current;
	}

	/* Call each function pointer registered */
	while (forward_head != 0) {
		current = forward_head;
		forward_head = current->next;
		current->func();
		kfree_type(struct init_list_entry, current);
	}
}