drivers/scsi/arm/queue.c

   1 /*
   2  *  linux/drivers/acorn/scsi/queue.c: queue handling primitives
   3  *
   4  *  Copyright (C) 1997-2000 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  *  Changelog:
  11  *   15-Sep-1997 RMK    Created.
  12  *   11-Oct-1997 RMK    Corrected problem with queue_remove_exclude
  13  *                      not updating internal linked list properly
  14  *                      (was causing commands to go missing).
  15  *   30-Aug-2000 RMK    Use Linux list handling and spinlocks
  16  */
  17 #include <linux/module.h>
  18 #include <linux/blkdev.h>
  19 #include <linux/kernel.h>
  20 #include <linux/string.h>
  21 #include <linux/slab.h>
  22 #include <linux/spinlock.h>
  23 #include <linux/list.h>
  24 #include <linux/init.h>
  25
  26 #include "../scsi.h"
  27
  28 #define DEBUG
  29
  30 typedef struct queue_entry {
  31         struct list_head   list;
  32         struct scsi_cmnd   *SCpnt;
  33 #ifdef DEBUG
  34         unsigned long      magic;
  35 #endif
  36 } QE_t;
  37
  38 #ifdef DEBUG
  39 #define QUEUE_MAGIC_FREE        0xf7e1c9a3
  40 #define QUEUE_MAGIC_USED        0xf7e1cc33
  41
  42 #define SET_MAGIC(q,m)  ((q)->magic = (m))
  43 #define BAD_MAGIC(q,m)  ((q)->magic != (m))
  44 #else
  45 #define SET_MAGIC(q,m)  do { } while (0)
  46 #define BAD_MAGIC(q,m)  (0)
  47 #endif
  48
  49 #include "queue.h"
  50
  51 #define NR_QE   32
  52
  53 /*
  54  * Function: void queue_initialise (Queue_t *queue)
  55  * Purpose : initialise a queue
  56  * Params  : queue - queue to initialise
  57  */
  58 int queue_initialise (Queue_t *queue)
  59 {
  60         unsigned int nqueues = NR_QE;
  61         QE_t *q;
  62
  63         spin_lock_init(&queue->queue_lock);
  64         INIT_LIST_HEAD(&queue->head);
  65         INIT_LIST_HEAD(&queue->free);
  66
  67         /*
  68          * If life was easier, then SCpnt would have a
  69          * host-available list head, and we wouldn't
  70          * need to keep free lists or allocate this
  71          * memory.
  72          */
  73         queue->alloc = q = kmalloc(sizeof(QE_t) * nqueues, GFP_KERNEL);
  74         if (q) {
  75                 for (; nqueues; q++, nqueues--) {
  76                         SET_MAGIC(q, QUEUE_MAGIC_FREE);
  77                         q->SCpnt = NULL;
  78                         list_add(&q->list, &queue->free);
  79                 }
  80         }
  81
  82         return queue->alloc != NULL;
  83 }
  84
  85 /*
  86  * Function: void queue_free (Queue_t *queue)
  87  * Purpose : free a queue
  88  * Params  : queue - queue to free
  89  */
  90 void queue_free (Queue_t *queue)
  91 {
  92         if (!list_empty(&queue->head))
  93                 printk(KERN_WARNING "freeing non-empty queue %p\n", queue);
  94         kfree(queue->alloc);
  95 }
  96
  97
  98 /*
  99  * Function: int __queue_add(Queue_t *queue, struct scsi_cmnd *SCpnt, int head)
 100  * Purpose : Add a new command onto a queue, adding REQUEST_SENSE to head.
 101  * Params  : queue - destination queue
 102  *           SCpnt - command to add
 103  *           head  - add command to head of queue
 104  * Returns : 0 on error, !0 on success
 105  */
 106 int __queue_add(Queue_t *queue, struct scsi_cmnd *SCpnt, int head)
 107 {
 108         unsigned long flags;
 109         struct list_head *l;
 110         QE_t *q;
 111         int ret = 0;
 112
 113         spin_lock_irqsave(&queue->queue_lock, flags);
 114         if (list_empty(&queue->free))
 115                 goto empty;
 116
 117         l = queue->free.next;
 118         list_del(l);
 119
 120         q = list_entry(l, QE_t, list);
 121         BUG_ON(BAD_MAGIC(q, QUEUE_MAGIC_FREE));
 122
 123         SET_MAGIC(q, QUEUE_MAGIC_USED);
 124         q->SCpnt = SCpnt;
 125
 126         if (head)
 127                 list_add(l, &queue->head);
 128         else
 129                 list_add_tail(l, &queue->head);
 130
 131         ret = 1;
 132 empty:
 133         spin_unlock_irqrestore(&queue->queue_lock, flags);
 134         return ret;
 135 }
 136
 137 static struct scsi_cmnd *__queue_remove(Queue_t *queue, struct list_head *ent)
 138 {
 139         QE_t *q;
 140
 141         /*
 142          * Move the entry from the "used" list onto the "free" list
 143          */
 144         list_del(ent);
 145         q = list_entry(ent, QE_t, list);
 146         BUG_ON(BAD_MAGIC(q, QUEUE_MAGIC_USED));
 147
 148         SET_MAGIC(q, QUEUE_MAGIC_FREE);
 149         list_add(ent, &queue->free);
 150
 151         return q->SCpnt;
 152 }
 153
 154 /*
 155  * Function: struct scsi_cmnd *queue_remove_exclude (queue, exclude)
 156  * Purpose : remove a SCSI command from a queue
 157  * Params  : queue   - queue to remove command from
 158  *           exclude - bit array of target&lun which is busy
 159  * Returns : struct scsi_cmnd if successful (and a reference), or NULL if no command available
 160  */
 161 struct scsi_cmnd *queue_remove_exclude(Queue_t *queue, unsigned long *exclude)
 162 {
 163         unsigned long flags;
 164         struct list_head *l;
 165         struct scsi_cmnd *SCpnt = NULL;
 166
 167         spin_lock_irqsave(&queue->queue_lock, flags);
 168         list_for_each(l, &queue->head) {
 169                 QE_t *q = list_entry(l, QE_t, list);
 170                 if (!test_bit(q->SCpnt->device->id * 8 + q->SCpnt->device->lun, exclude)) {
 171                         SCpnt = __queue_remove(queue, l);
 172                         break;
 173                 }
 174         }
 175         spin_unlock_irqrestore(&queue->queue_lock, flags);
 176
 177         return SCpnt;
 178 }
 179
 180 /*
 181  * Function: struct scsi_cmnd *queue_remove (queue)
 182  * Purpose : removes first SCSI command from a queue
 183  * Params  : queue   - queue to remove command from
 184  * Returns : struct scsi_cmnd if successful (and a reference), or NULL if no command available
 185  */
 186 struct scsi_cmnd *queue_remove(Queue_t *queue)
 187 {
 188         unsigned long flags;
 189         struct scsi_cmnd *SCpnt = NULL;
 190
 191         spin_lock_irqsave(&queue->queue_lock, flags);
 192         if (!list_empty(&queue->head))
 193                 SCpnt = __queue_remove(queue, queue->head.next);
 194         spin_unlock_irqrestore(&queue->queue_lock, flags);
 195
 196         return SCpnt;
 197 }
 198
 199 /*
 200  * Function: struct scsi_cmnd *queue_remove_tgtluntag (queue, target, lun, tag)
 201  * Purpose : remove a SCSI command from the queue for a specified target/lun/tag
 202  * Params  : queue  - queue to remove command from
 203  *           target - target that we want
 204  *           lun    - lun on device
 205  *           tag    - tag on device
 206  * Returns : struct scsi_cmnd if successful, or NULL if no command satisfies requirements
 207  */
 208 struct scsi_cmnd *queue_remove_tgtluntag(Queue_t *queue, int target, int lun,
 209                                          int tag)
 210 {
 211         unsigned long flags;
 212         struct list_head *l;
 213         struct scsi_cmnd *SCpnt = NULL;
 214
 215         spin_lock_irqsave(&queue->queue_lock, flags);
 216         list_for_each(l, &queue->head) {
 217                 QE_t *q = list_entry(l, QE_t, list);
 218                 if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun &&
 219                     q->SCpnt->tag == tag) {
 220                         SCpnt = __queue_remove(queue, l);
 221                         break;
 222                 }
 223         }
 224         spin_unlock_irqrestore(&queue->queue_lock, flags);
 225
 226         return SCpnt;
 227 }
 228
 229 /*
 230  * Function: queue_remove_all_target(queue, target)
 231  * Purpose : remove all SCSI commands from the queue for a specified target
 232  * Params  : queue  - queue to remove command from
 233  *           target - target device id
 234  * Returns : nothing
 235  */
 236 void queue_remove_all_target(Queue_t *queue, int target)
 237 {
 238         unsigned long flags;
 239         struct list_head *l;
 240
 241         spin_lock_irqsave(&queue->queue_lock, flags);
 242         list_for_each(l, &queue->head) {
 243                 QE_t *q = list_entry(l, QE_t, list);
 244                 if (q->SCpnt->device->id == target)
 245                         __queue_remove(queue, l);
 246         }
 247         spin_unlock_irqrestore(&queue->queue_lock, flags);
 248 }
 249
 250 /*
 251  * Function: int queue_probetgtlun (queue, target, lun)
 252  * Purpose : check to see if we have a command in the queue for the specified
 253  *           target/lun.
 254  * Params  : queue  - queue to look in
 255  *           target - target we want to probe
 256  *           lun    - lun on target
 257  * Returns : 0 if not found, != 0 if found
 258  */
 259 int queue_probetgtlun (Queue_t *queue, int target, int lun)
 260 {
 261         unsigned long flags;
 262         struct list_head *l;
 263         int found = 0;
 264
 265         spin_lock_irqsave(&queue->queue_lock, flags);
 266         list_for_each(l, &queue->head) {
 267                 QE_t *q = list_entry(l, QE_t, list);
 268                 if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun) {
 269                         found = 1;
 270                         break;
 271                 }
 272         }
 273         spin_unlock_irqrestore(&queue->queue_lock, flags);
 274
 275         return found;
 276 }
 277
 278 /*
 279  * Function: int queue_remove_cmd(Queue_t *queue, struct scsi_cmnd *SCpnt)
 280  * Purpose : remove a specific command from the queues
 281  * Params  : queue - queue to look in
 282  *           SCpnt - command to find
 283  * Returns : 0 if not found
 284  */
 285 int queue_remove_cmd(Queue_t *queue, struct scsi_cmnd *SCpnt)
 286 {
 287         unsigned long flags;
 288         struct list_head *l;
 289         int found = 0;
 290
 291         spin_lock_irqsave(&queue->queue_lock, flags);
 292         list_for_each(l, &queue->head) {
 293                 QE_t *q = list_entry(l, QE_t, list);
 294                 if (q->SCpnt == SCpnt) {
 295                         __queue_remove(queue, l);
 296                         found = 1;
 297                         break;
 298                 }
 299         }
 300         spin_unlock_irqrestore(&queue->queue_lock, flags);
 301
 302         return found;
 303 }
 304
 305 EXPORT_SYMBOL(queue_initialise);
 306 EXPORT_SYMBOL(queue_free);
 307 EXPORT_SYMBOL(__queue_add);
 308 EXPORT_SYMBOL(queue_remove);
 309 EXPORT_SYMBOL(queue_remove_exclude);
 310 EXPORT_SYMBOL(queue_remove_tgtluntag);
 311 EXPORT_SYMBOL(queue_remove_cmd);
 312 EXPORT_SYMBOL(queue_remove_all_target);
 313 EXPORT_SYMBOL(queue_probetgtlun);
 314
 315 MODULE_AUTHOR("Russell King");
 316 MODULE_DESCRIPTION("SCSI command queueing");
 317 MODULE_LICENSE("GPL");