xref: /openbmc/linux/include/uapi/linux/mqueue.h (revision bb970707)
1 /* Copyright (C) 2003 Krzysztof Benedyczak & Michal Wronski
2 
3    This program is free software; you can redistribute it and/or
4    modify it under the terms of the GNU Lesser General Public
5    License as published by the Free Software Foundation; either
6    version 2.1 of the License, or (at your option) any later version.
7 
8    It is distributed in the hope that it will be useful,
9    but WITHOUT ANY WARRANTY; without even the implied warranty of
10    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11    Lesser General Public License for more details.
12 
13    You should have received a copy of the GNU Lesser General Public
14    License along with this software; if not, write to the Free
15    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
16    02111-1307 USA.  */
17 
18 #ifndef _LINUX_MQUEUE_H
19 #define _LINUX_MQUEUE_H
20 
21 #define MQ_PRIO_MAX 	32768
22 /* per-uid limit of kernel memory used by mqueue, in bytes */
23 #define MQ_BYTES_MAX	819200
24 
25 struct mq_attr {
26 	__kernel_long_t	mq_flags;	/* message queue flags			*/
27 	__kernel_long_t	mq_maxmsg;	/* maximum number of messages		*/
28 	__kernel_long_t	mq_msgsize;	/* maximum message size			*/
29 	__kernel_long_t	mq_curmsgs;	/* number of messages currently queued	*/
30 	__kernel_long_t	__reserved[4];	/* ignored for input, zeroed for output */
31 };
32 
33 /*
34  * SIGEV_THREAD implementation:
35  * SIGEV_THREAD must be implemented in user space. If SIGEV_THREAD is passed
36  * to mq_notify, then
37  * - sigev_signo must be the file descriptor of an AF_NETLINK socket. It's not
38  *   necessary that the socket is bound.
39  * - sigev_value.sival_ptr must point to a cookie that is NOTIFY_COOKIE_LEN
40  *   bytes long.
41  * If the notification is triggered, then the cookie is sent to the netlink
42  * socket. The last byte of the cookie is replaced with the NOTIFY_?? codes:
43  * NOTIFY_WOKENUP if the notification got triggered, NOTIFY_REMOVED if it was
44  * removed, either due to a close() on the message queue fd or due to a
45  * mq_notify() that removed the notification.
46  */
47 #define NOTIFY_NONE	0
48 #define NOTIFY_WOKENUP	1
49 #define NOTIFY_REMOVED	2
50 
51 #define NOTIFY_COOKIE_LEN	32
52 
53 #endif
54