1/* SPDX-License-Identifier: LGPL-2.1+ WITH Linux-syscall-note */
2/* Copyright (C) 2003 Krzysztof Benedyczak & Michal Wronski
3
4   This program is free software; you can redistribute it and/or
5   modify it under the terms of the GNU Lesser General Public
6   License as published by the Free Software Foundation; either
7   version 2.1 of the License, or (at your option) any later version.
8
9   It is distributed in the hope that it will be useful,
10   but WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12   Lesser General Public License for more details.
13
14   You should have received a copy of the GNU Lesser General Public
15   License along with this software; if not, write to the Free
16   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
17   02111-1307 USA.  */
18
19#ifndef _LINUX_MQUEUE_H
20#define _LINUX_MQUEUE_H
21
22#include <linux/types.h>
23
24#define MQ_PRIO_MAX 	32768
25/* per-uid limit of kernel memory used by mqueue, in bytes */
26#define MQ_BYTES_MAX	819200
27
28struct mq_attr {
29	__kernel_long_t	mq_flags;	/* message queue flags			*/
30	__kernel_long_t	mq_maxmsg;	/* maximum number of messages		*/
31	__kernel_long_t	mq_msgsize;	/* maximum message size			*/
32	__kernel_long_t	mq_curmsgs;	/* number of messages currently queued	*/
33	__kernel_long_t	__reserved[4];	/* ignored for input, zeroed for output */
34};
35
36/*
37 * SIGEV_THREAD implementation:
38 * SIGEV_THREAD must be implemented in user space. If SIGEV_THREAD is passed
39 * to mq_notify, then
40 * - sigev_signo must be the file descriptor of an AF_NETLINK socket. It's not
41 *   necessary that the socket is bound.
42 * - sigev_value.sival_ptr must point to a cookie that is NOTIFY_COOKIE_LEN
43 *   bytes long.
44 * If the notification is triggered, then the cookie is sent to the netlink
45 * socket. The last byte of the cookie is replaced with the NOTIFY_?? codes:
46 * NOTIFY_WOKENUP if the notification got triggered, NOTIFY_REMOVED if it was
47 * removed, either due to a close() on the message queue fd or due to a
48 * mq_notify() that removed the notification.
49 */
50#define NOTIFY_NONE	0
51#define NOTIFY_WOKENUP	1
52#define NOTIFY_REMOVED	2
53
54#define NOTIFY_COOKIE_LEN	32
55
56#endif
57