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/*
* linux/drivers/acorn/scsi/queue.c: queue handling primitives
*
* Copyright (C) 1997-2000 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Changelog:
* 15-Sep-1997 RMK Created.
* 11-Oct-1997 RMK Corrected problem with queue_remove_exclude
* not updating internal linked list properly
* (was causing commands to go missing).
* 30-Aug-2000 RMK Use Linux list handling and spinlocks
*/
#include <linux/module.h>
#include <linux/blk.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/init.h>
#include "../../scsi/scsi.h"
#define DEBUG
typedef struct queue_entry {
struct list_head list;
Scsi_Cmnd *SCpnt;
#ifdef DEBUG
unsigned long magic;
#endif
} QE_t;
#ifdef DEBUG
#define QUEUE_MAGIC_FREE 0xf7e1c9a3
#define QUEUE_MAGIC_USED 0xf7e1cc33
#define SET_MAGIC(q,m) ((q)->magic = (m))
#define BAD_MAGIC(q,m) ((q)->magic != (m))
#else
#define SET_MAGIC(q,m) do { } while (0)
#define BAD_MAGIC(q,m) (0)
#endif
#include "queue.h"
#define NR_QE 32
/*
* Function: void queue_initialise (Queue_t *queue)
* Purpose : initialise a queue
* Params : queue - queue to initialise
*/
int queue_initialise (Queue_t *queue)
{
unsigned int nqueues = NR_QE;
QE_t *q;
spin_lock_init(&queue->queue_lock);
INIT_LIST_HEAD(&queue->head);
INIT_LIST_HEAD(&queue->free);
/*
* If life was easier, then SCpnt would have a
* host-available list head, and we wouldn't
* need to keep free lists or allocate this
* memory.
*/
queue->alloc = q = kmalloc(sizeof(QE_t) * nqueues, GFP_KERNEL);
if (q) {
for (; nqueues; q++, nqueues--) {
SET_MAGIC(q, QUEUE_MAGIC_FREE);
q->SCpnt = NULL;
list_add(&q->list, &queue->free);
}
}
return queue->alloc != NULL;
}
/*
* Function: void queue_free (Queue_t *queue)
* Purpose : free a queue
* Params : queue - queue to free
*/
void queue_free (Queue_t *queue)
{
if (!list_empty(&queue->head))
printk(KERN_WARNING "freeing non-empty queue %p\n", queue);
if (queue->alloc)
kfree(queue->alloc);
}
/*
* Function: int queue_add_cmd(Queue_t *queue, Scsi_Cmnd *SCpnt, int head)
* Purpose : Add a new command onto a queue, adding REQUEST_SENSE to head.
* Params : queue - destination queue
* SCpnt - command to add
* head - add command to head of queue
* Returns : 0 on error, !0 on success
*/
int __queue_add(Queue_t *queue, Scsi_Cmnd *SCpnt, int head)
{
unsigned long flags;
struct list_head *l;
QE_t *q;
int ret = 0;
spin_lock_irqsave(&queue->queue_lock, flags);
if (list_empty(&queue->free))
goto empty;
l = queue->free.next;
list_del(l);
q = list_entry(l, QE_t, list);
if (BAD_MAGIC(q, QUEUE_MAGIC_FREE))
BUG();
SET_MAGIC(q, QUEUE_MAGIC_USED);
q->SCpnt = SCpnt;
if (head)
list_add(l, &queue->head);
else
list_add_tail(l, &queue->head);
ret = 1;
empty:
spin_unlock_irqrestore(&queue->queue_lock, flags);
return ret;
}
static Scsi_Cmnd *__queue_remove(Queue_t *queue, struct list_head *ent)
{
QE_t *q;
/*
* Move the entry from the "used" list onto the "free" list
*/
list_del(ent);
q = list_entry(ent, QE_t, list);
if (BAD_MAGIC(q, QUEUE_MAGIC_USED))
BUG();
SET_MAGIC(q, QUEUE_MAGIC_FREE);
list_add(ent, &queue->free);
return q->SCpnt;
}
/*
* Function: Scsi_Cmnd *queue_remove_exclude (queue, exclude)
* Purpose : remove a SCSI command from a queue
* Params : queue - queue to remove command from
* exclude - bit array of target&lun which is busy
* Returns : Scsi_Cmnd if successful (and a reference), or NULL if no command available
*/
Scsi_Cmnd *queue_remove_exclude(Queue_t *queue, void *exclude)
{
unsigned long flags;
struct list_head *l;
Scsi_Cmnd *SCpnt = NULL;
spin_lock_irqsave(&queue->queue_lock, flags);
list_for_each(l, &queue->head) {
QE_t *q = list_entry(l, QE_t, list);
if (!test_bit(q->SCpnt->target * 8 + q->SCpnt->lun, exclude)) {
SCpnt = __queue_remove(queue, l);
break;
}
}
spin_unlock_irqrestore(&queue->queue_lock, flags);
return SCpnt;
}
/*
* Function: Scsi_Cmnd *queue_remove (queue)
* Purpose : removes first SCSI command from a queue
* Params : queue - queue to remove command from
* Returns : Scsi_Cmnd if successful (and a reference), or NULL if no command available
*/
Scsi_Cmnd *queue_remove(Queue_t *queue)
{
unsigned long flags;
Scsi_Cmnd *SCpnt = NULL;
spin_lock_irqsave(&queue->queue_lock, flags);
if (!list_empty(&queue->head))
SCpnt = __queue_remove(queue, queue->head.next);
spin_unlock_irqrestore(&queue->queue_lock, flags);
return SCpnt;
}
/*
* Function: Scsi_Cmnd *queue_remove_tgtluntag (queue, target, lun, tag)
* Purpose : remove a SCSI command from the queue for a specified target/lun/tag
* Params : queue - queue to remove command from
* target - target that we want
* lun - lun on device
* tag - tag on device
* Returns : Scsi_Cmnd if successful, or NULL if no command satisfies requirements
*/
Scsi_Cmnd *queue_remove_tgtluntag (Queue_t *queue, int target, int lun, int tag)
{
unsigned long flags;
struct list_head *l;
Scsi_Cmnd *SCpnt = NULL;
spin_lock_irqsave(&queue->queue_lock, flags);
list_for_each(l, &queue->head) {
QE_t *q = list_entry(l, QE_t, list);
if (q->SCpnt->target == target && q->SCpnt->lun == lun &&
q->SCpnt->tag == tag) {
SCpnt = __queue_remove(queue, l);
break;
}
}
spin_unlock_irqrestore(&queue->queue_lock, flags);
return SCpnt;
}
/*
* Function: int queue_probetgtlun (queue, target, lun)
* Purpose : check to see if we have a command in the queue for the specified
* target/lun.
* Params : queue - queue to look in
* target - target we want to probe
* lun - lun on target
* Returns : 0 if not found, != 0 if found
*/
int queue_probetgtlun (Queue_t *queue, int target, int lun)
{
unsigned long flags;
struct list_head *l;
int found = 0;
spin_lock_irqsave(&queue->queue_lock, flags);
list_for_each(l, &queue->head) {
QE_t *q = list_entry(l, QE_t, list);
if (q->SCpnt->target == target && q->SCpnt->lun == lun) {
found = 1;
break;
}
}
spin_unlock_irqrestore(&queue->queue_lock, flags);
return found;
}
/*
* Function: int queue_remove_cmd(Queue_t *queue, Scsi_Cmnd *SCpnt)
* Purpose : remove a specific command from the queues
* Params : queue - queue to look in
* SCpnt - command to find
* Returns : 0 if not found
*/
int queue_remove_cmd(Queue_t *queue, Scsi_Cmnd *SCpnt)
{
unsigned long flags;
struct list_head *l;
int found = 0;
spin_lock_irqsave(&queue->queue_lock, flags);
list_for_each(l, &queue->head) {
QE_t *q = list_entry(l, QE_t, list);
if (q->SCpnt == SCpnt) {
__queue_remove(queue, l);
found = 1;
break;
}
}
spin_unlock_irqrestore(&queue->queue_lock, flags);
return found;
}
EXPORT_SYMBOL(queue_initialise);
EXPORT_SYMBOL(queue_free);
EXPORT_SYMBOL(__queue_add);
EXPORT_SYMBOL(queue_remove);
EXPORT_SYMBOL(queue_remove_exclude);
EXPORT_SYMBOL(queue_remove_tgtluntag);
EXPORT_SYMBOL(queue_remove_cmd);
EXPORT_SYMBOL(queue_probetgtlun);
MODULE_AUTHOR("Russell King");
MODULE_DESCRIPTION("SCSI command queueing");
MODULE_LICENSE("GPL");
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