// SPDX-License-Identifier: GPL-2.0-only/* *  linux/drivers/acorn/scsi/msgqueue.c * *  Copyright (C) 1997-1998 Russell King * *  message queue handling */#include <linux/module.h>#include <linux/kernel.h>#include <linux/stddef.h>#include <linux/init.h> #include "msgqueue.h" /* * Function: struct msgqueue_entry *mqe_alloc(MsgQueue_t *msgq) * Purpose : Allocate a message queue entry * Params  : msgq - message queue to claim entry for * Returns : message queue entry or NULL. */static struct msgqueue_entry *mqe_alloc(MsgQueue_t *msgq){	struct msgqueue_entry *mq; 	if ((mq = msgq->free) != NULL)		msgq->free = mq->next; 	return mq;} /* * Function: void mqe_free(MsgQueue_t *msgq, struct msgqueue_entry *mq) * Purpose : free a message queue entry * Params  : msgq - message queue to free entry from *	     mq   - message queue entry to free */static void mqe_free(MsgQueue_t *msgq, struct msgqueue_entry *mq){	if (mq) {		mq->next = msgq->free;		msgq->free = mq;	}} /* * Function: void msgqueue_initialise(MsgQueue_t *msgq) * Purpose : initialise a message queue * Params  : msgq - queue to initialise */void msgqueue_initialise(MsgQueue_t *msgq){	int i; 	msgq->qe = NULL;	msgq->free = &msgq->entries[0]; 	for (i = 0; i < NR_MESSAGES; i++)		msgq->entries[i].next = &msgq->entries[i + 1]; 	msgq->entries[NR_MESSAGES - 1].next = NULL;}  /* * Function: void msgqueue_free(MsgQueue_t *msgq) * Purpose : free a queue * Params  : msgq - queue to free */void msgqueue_free(MsgQueue_t *msgq){} /* * Function: int msgqueue_msglength(MsgQueue_t *msgq) * Purpose : calculate the total length of all messages on the message queue * Params  : msgq - queue to examine * Returns : number of bytes of messages in queue */int msgqueue_msglength(MsgQueue_t *msgq){	struct msgqueue_entry *mq = msgq->qe;	int length = 0; 	for (mq = msgq->qe; mq; mq = mq->next)		length += mq->msg.length; 	return length;} /* * Function: struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno) * Purpose : return a message * Params  : msgq   - queue to obtain message from *	   : msgno  - message number * Returns : pointer to message string, or NULL */struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno){	struct msgqueue_entry *mq; 	for (mq = msgq->qe; mq && msgno; mq = mq->next, msgno--); 	return mq ? &mq->msg : NULL;} /* * Function: int msgqueue_addmsg(MsgQueue_t *msgq, int length, ...) * Purpose : add a message onto a message queue * Params  : msgq   - queue to add message on *	     length - length of message *	     ...    - message bytes * Returns : != 0 if successful */int msgqueue_addmsg(MsgQueue_t *msgq, int length, ...){	struct msgqueue_entry *mq = mqe_alloc(msgq);	va_list ap; 	if (mq) {		struct msgqueue_entry **mqp;		int i; 		va_start(ap, length);		for (i = 0; i < length; i++)			mq->msg.msg[i] = va_arg(ap, unsigned int);		va_end(ap); 		mq->msg.length = length;		mq->msg.fifo = 0;		mq->next = NULL; 		mqp = &msgq->qe;		while (*mqp)			mqp = &(*mqp)->next; 		*mqp = mq;	} 	return mq != NULL;} /* * Function: void msgqueue_flush(MsgQueue_t *msgq) * Purpose : flush all messages from message queue * Params  : msgq - queue to flush */void msgqueue_flush(MsgQueue_t *msgq){	struct msgqueue_entry *mq, *mqnext; 	for (mq = msgq->qe; mq; mq = mqnext) {		mqnext = mq->next;		mqe_free(msgq, mq);	}	msgq->qe = NULL;} EXPORT_SYMBOL(msgqueue_initialise);EXPORT_SYMBOL(msgqueue_free);EXPORT_SYMBOL(msgqueue_msglength);EXPORT_SYMBOL(msgqueue_getmsg);EXPORT_SYMBOL(msgqueue_addmsg);EXPORT_SYMBOL(msgqueue_flush); MODULE_AUTHOR("Russell King");MODULE_DESCRIPTION("SCSI message queue handling");MODULE_LICENSE("GPL");