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