drivers/scsi/arm/queue.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/drivers/acorn/scsi/queue.c: queue handling primitives
   4  *
   5  *  Copyright (C) 1997-2000 Russell King
   6  *
   7  *  Changelog:
   8  *   15-Sep-1997 RMK    Created.
   9  *   11-Oct-1997 RMK    Corrected problem with queue_remove_exclude
  10  *                      not updating internal linked list properly
  11  *                      (was causing commands to go missing).
  12  *   30-Aug-2000 RMK    Use Linux list handling and spinlocks
  13  */
  14 #include <linux/module.h>
  15 #include <linux/blkdev.h>
  16 #include <linux/kernel.h>
  17 #include <linux/string.h>
  18 #include <linux/slab.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/list.h>
  21 #include <linux/init.h>
  22
  23 #include "../scsi.h"
  24
  25 #define DEBUG
  26
  27 typedef struct queue_entry {
  28         struct list_head   list;
  29         struct scsi_cmnd   *SCpnt;
  30 #ifdef DEBUG
  31         unsigned long      magic;
  32 #endif
  33 } QE_t;
  34
  35 #ifdef DEBUG
  36 #define QUEUE_MAGIC_FREE        0xf7e1c9a3
  37 #define QUEUE_MAGIC_USED        0xf7e1cc33
  38
  39 #define SET_MAGIC(q,m)  ((q)->magic = (m))
  40 #define BAD_MAGIC(q,m)  ((q)->magic != (m))
  41 #else
  42 #define SET_MAGIC(q,m)  do { } while (0)
  43 #define BAD_MAGIC(q,m)  (0)
  44 #endif
  45
  46 #include "queue.h"
  47
  48 #define NR_QE   32
  49
  50 /*
  51  * Function: void queue_initialise (Queue_t *queue)
  52  * Purpose : initialise a queue
  53  * Params  : queue - queue to initialise
  54  */
  55 int queue_initialise (Queue_t *queue)
  56 {
  57         unsigned int nqueues = NR_QE;
  58         QE_t *q;
  59
  60         spin_lock_init(&queue->queue_lock);
  61         INIT_LIST_HEAD(&queue->head);
  62         INIT_LIST_HEAD(&queue->free);
  63
  64         /*
  65          * If life was easier, then SCpnt would have a
  66          * host-available list head, and we wouldn't
  67          * need to keep free lists or allocate this
  68          * memory.
  69          */
  70         queue->alloc = q = kmalloc_array(nqueues, sizeof(QE_t), GFP_KERNEL);
  71         if (q) {
  72                 for (; nqueues; q++, nqueues--) {
  73                         SET_MAGIC(q, QUEUE_MAGIC_FREE);
  74                         q->SCpnt = NULL;
  75                         list_add(&q->list, &queue->free);
  76                 }
  77         }
  78
  79         return queue->alloc != NULL;
  80 }
  81
  82 /*
  83  * Function: void queue_free (Queue_t *queue)
  84  * Purpose : free a queue
  85  * Params  : queue - queue to free
  86  */
  87 void queue_free (Queue_t *queue)
  88 {
  89         if (!list_empty(&queue->head))
  90                 printk(KERN_WARNING "freeing non-empty queue %p\n", queue);
  91         kfree(queue->alloc);
  92 }
  93
  94
  95 /*
  96  * Function: int __queue_add(Queue_t *queue, struct scsi_cmnd *SCpnt, int head)
  97  * Purpose : Add a new command onto a queue, adding REQUEST_SENSE to head.
  98  * Params  : queue - destination queue
  99  *           SCpnt - command to add
 100  *           head  - add command to head of queue
 101  * Returns : 0 on error, !0 on success
 102  */
 103 int __queue_add(Queue_t *queue, struct scsi_cmnd *SCpnt, int head)
 104 {
 105         unsigned long flags;
 106         struct list_head *l;
 107         QE_t *q;
 108         int ret = 0;
 109
 110         spin_lock_irqsave(&queue->queue_lock, flags);
 111         if (list_empty(&queue->free))
 112                 goto empty;
 113
 114         l = queue->free.next;
 115         list_del(l);
 116
 117         q = list_entry(l, QE_t, list);
 118         BUG_ON(BAD_MAGIC(q, QUEUE_MAGIC_FREE));
 119
 120         SET_MAGIC(q, QUEUE_MAGIC_USED);
 121         q->SCpnt = SCpnt;
 122
 123         if (head)
 124                 list_add(l, &queue->head);
 125         else
 126                 list_add_tail(l, &queue->head);
 127
 128         ret = 1;
 129 empty:
 130         spin_unlock_irqrestore(&queue->queue_lock, flags);
 131         return ret;
 132 }
 133
 134 static struct scsi_cmnd *__queue_remove(Queue_t *queue, struct list_head *ent)
 135 {
 136         QE_t *q;
 137
 138         /*
 139          * Move the entry from the "used" list onto the "free" list
 140          */
 141         list_del(ent);
 142         q = list_entry(ent, QE_t, list);
 143         BUG_ON(BAD_MAGIC(q, QUEUE_MAGIC_USED));
 144
 145         SET_MAGIC(q, QUEUE_MAGIC_FREE);
 146         list_add(ent, &queue->free);
 147
 148         return q->SCpnt;
 149 }
 150
 151 /*
 152  * Function: struct scsi_cmnd *queue_remove_exclude (queue, exclude)
 153  * Purpose : remove a SCSI command from a queue
 154  * Params  : queue   - queue to remove command from
 155  *           exclude - bit array of target&lun which is busy
 156  * Returns : struct scsi_cmnd if successful (and a reference), or NULL if no command available
 157  */
 158 struct scsi_cmnd *queue_remove_exclude(Queue_t *queue, unsigned long *exclude)
 159 {
 160         unsigned long flags;
 161         struct list_head *l;
 162         struct scsi_cmnd *SCpnt = NULL;
 163
 164         spin_lock_irqsave(&queue->queue_lock, flags);
 165         list_for_each(l, &queue->head) {
 166                 QE_t *q = list_entry(l, QE_t, list);
 167                 if (!test_bit(q->SCpnt->device->id * 8 +
 168                               (u8)(q->SCpnt->device->lun & 0x7), exclude)) {
 169                         SCpnt = __queue_remove(queue, l);
 170                         break;
 171                 }
 172         }
 173         spin_unlock_irqrestore(&queue->queue_lock, flags);
 174
 175         return SCpnt;
 176 }
 177
 178 /*
 179  * Function: struct scsi_cmnd *queue_remove (queue)
 180  * Purpose : removes first SCSI command from a queue
 181  * Params  : queue   - queue to remove command from
 182  * Returns : struct scsi_cmnd if successful (and a reference), or NULL if no command available
 183  */
 184 struct scsi_cmnd *queue_remove(Queue_t *queue)
 185 {
 186         unsigned long flags;
 187         struct scsi_cmnd *SCpnt = NULL;
 188
 189         spin_lock_irqsave(&queue->queue_lock, flags);
 190         if (!list_empty(&queue->head))
 191                 SCpnt = __queue_remove(queue, queue->head.next);
 192         spin_unlock_irqrestore(&queue->queue_lock, flags);
 193
 194         return SCpnt;
 195 }
 196
 197 /*
 198  * Function: struct scsi_cmnd *queue_remove_tgtluntag (queue, target, lun, tag)
 199  * Purpose : remove a SCSI command from the queue for a specified target/lun/tag
 200  * Params  : queue  - queue to remove command from
 201  *           target - target that we want
 202  *           lun    - lun on device
 203  *           tag    - tag on device
 204  * Returns : struct scsi_cmnd if successful, or NULL if no command satisfies requirements
 205  */
 206 struct scsi_cmnd *queue_remove_tgtluntag(Queue_t *queue, int target, int lun,
 207                                          int tag)
 208 {
 209         unsigned long flags;
 210         struct list_head *l;
 211         struct scsi_cmnd *SCpnt = NULL;
 212
 213         spin_lock_irqsave(&queue->queue_lock, flags);
 214         list_for_each(l, &queue->head) {
 215                 QE_t *q = list_entry(l, QE_t, list);
 216                 if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun &&
 217                     q->SCpnt->tag == tag) {
 218                         SCpnt = __queue_remove(queue, l);
 219                         break;
 220                 }
 221         }
 222         spin_unlock_irqrestore(&queue->queue_lock, flags);
 223
 224         return SCpnt;
 225 }
 226
 227 /*
 228  * Function: queue_remove_all_target(queue, target)
 229  * Purpose : remove all SCSI commands from the queue for a specified target
 230  * Params  : queue  - queue to remove command from
 231  *           target - target device id
 232  * Returns : nothing
 233  */
 234 void queue_remove_all_target(Queue_t *queue, int target)
 235 {
 236         unsigned long flags;
 237         struct list_head *l;
 238
 239         spin_lock_irqsave(&queue->queue_lock, flags);
 240         list_for_each(l, &queue->head) {
 241                 QE_t *q = list_entry(l, QE_t, list);
 242                 if (q->SCpnt->device->id == target)
 243                         __queue_remove(queue, l);
 244         }
 245         spin_unlock_irqrestore(&queue->queue_lock, flags);
 246 }
 247
 248 /*
 249  * Function: int queue_probetgtlun (queue, target, lun)
 250  * Purpose : check to see if we have a command in the queue for the specified
 251  *           target/lun.
 252  * Params  : queue  - queue to look in
 253  *           target - target we want to probe
 254  *           lun    - lun on target
 255  * Returns : 0 if not found, != 0 if found
 256  */
 257 int queue_probetgtlun (Queue_t *queue, int target, int lun)
 258 {
 259         unsigned long flags;
 260         struct list_head *l;
 261         int found = 0;
 262
 263         spin_lock_irqsave(&queue->queue_lock, flags);
 264         list_for_each(l, &queue->head) {
 265                 QE_t *q = list_entry(l, QE_t, list);
 266                 if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun) {
 267                         found = 1;
 268                         break;
 269                 }
 270         }
 271         spin_unlock_irqrestore(&queue->queue_lock, flags);
 272
 273         return found;
 274 }
 275
 276 /*
 277  * Function: int queue_remove_cmd(Queue_t *queue, struct scsi_cmnd *SCpnt)
 278  * Purpose : remove a specific command from the queues
 279  * Params  : queue - queue to look in
 280  *           SCpnt - command to find
 281  * Returns : 0 if not found
 282  */
 283 int queue_remove_cmd(Queue_t *queue, struct scsi_cmnd *SCpnt)
 284 {
 285         unsigned long flags;
 286         struct list_head *l;
 287         int found = 0;
 288
 289         spin_lock_irqsave(&queue->queue_lock, flags);
 290         list_for_each(l, &queue->head) {
 291                 QE_t *q = list_entry(l, QE_t, list);
 292                 if (q->SCpnt == SCpnt) {
 293                         __queue_remove(queue, l);
 294                         found = 1;
 295                         break;
 296                 }
 297         }
 298         spin_unlock_irqrestore(&queue->queue_lock, flags);
 299
 300         return found;
 301 }
 302
 303 EXPORT_SYMBOL(queue_initialise);
 304 EXPORT_SYMBOL(queue_free);
 305 EXPORT_SYMBOL(__queue_add);
 306 EXPORT_SYMBOL(queue_remove);
 307 EXPORT_SYMBOL(queue_remove_exclude);
 308 EXPORT_SYMBOL(queue_remove_tgtluntag);
 309 EXPORT_SYMBOL(queue_remove_cmd);
 310 EXPORT_SYMBOL(queue_remove_all_target);
 311 EXPORT_SYMBOL(queue_probetgtlun);
 312
 313 MODULE_AUTHOR("Russell King");
 314 MODULE_DESCRIPTION("SCSI command queueing");
 315 MODULE_LICENSE("GPL");