linux_kernel/include/linux/msg.h

#ifndef _LINUX_MSG_H
#define _LINUX_MSG_H

#include <linux/list.h>
#include <linux/time64.h>
#include <uapi/linux/msg.h>

/* one msg_msg structure for each message */
struct msg_msg {
	struct list_head m_list;
	long m_type;
	size_t m_ts;		/* message text size */
	struct msg_msgseg *next;
	void *security;
	/* the actual message follows immediately */
};

/* one msq_queue structure for each present queue on the system */
struct msg_queue {
	struct kern_ipc_perm q_perm;
	time64_t q_stime;		/* last msgsnd time */
	time64_t q_rtime;		/* last msgrcv time */
	time64_t q_ctime;		/* last change time */
	unsigned long q_cbytes;		/* current number of bytes on queue */
	unsigned long q_qnum;		/* number of messages in queue */
	unsigned long q_qbytes;		/* max number of bytes on queue */
	pid_t q_lspid;			/* pid of last msgsnd */
	pid_t q_lrpid;			/* last receive pid */

	struct list_head q_messages;
	struct list_head q_receivers;
	struct list_head q_senders;
} __randomize_layout;

#endif /* _LINUX_MSG_H */