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 + 171 (u8)(q->SCpnt->device->lun & 0x7), exclude)) { 172 SCpnt = __queue_remove(queue, l); 173 break; 174 } 175 } 176 spin_unlock_irqrestore(&queue->queue_lock, flags); 177 178 return SCpnt; 179 } 180 181 /* 182 * Function: struct scsi_cmnd *queue_remove (queue) 183 * Purpose : removes first SCSI command from a queue 184 * Params : queue - queue to remove command from 185 * Returns : struct scsi_cmnd if successful (and a reference), or NULL if no command available 186 */ 187 struct scsi_cmnd *queue_remove(Queue_t *queue) 188 { 189 unsigned long flags; 190 struct scsi_cmnd *SCpnt = NULL; 191 192 spin_lock_irqsave(&queue->queue_lock, flags); 193 if (!list_empty(&queue->head)) 194 SCpnt = __queue_remove(queue, queue->head.next); 195 spin_unlock_irqrestore(&queue->queue_lock, flags); 196 197 return SCpnt; 198 } 199 200 /* 201 * Function: struct scsi_cmnd *queue_remove_tgtluntag (queue, target, lun, tag) 202 * Purpose : remove a SCSI command from the queue for a specified target/lun/tag 203 * Params : queue - queue to remove command from 204 * target - target that we want 205 * lun - lun on device 206 * tag - tag on device 207 * Returns : struct scsi_cmnd if successful, or NULL if no command satisfies requirements 208 */ 209 struct scsi_cmnd *queue_remove_tgtluntag(Queue_t *queue, int target, int lun, 210 int tag) 211 { 212 unsigned long flags; 213 struct list_head *l; 214 struct scsi_cmnd *SCpnt = NULL; 215 216 spin_lock_irqsave(&queue->queue_lock, flags); 217 list_for_each(l, &queue->head) { 218 QE_t *q = list_entry(l, QE_t, list); 219 if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun && 220 q->SCpnt->tag == tag) { 221 SCpnt = __queue_remove(queue, l); 222 break; 223 } 224 } 225 spin_unlock_irqrestore(&queue->queue_lock, flags); 226 227 return SCpnt; 228 } 229 230 /* 231 * Function: queue_remove_all_target(queue, target) 232 * Purpose : remove all SCSI commands from the queue for a specified target 233 * Params : queue - queue to remove command from 234 * target - target device id 235 * Returns : nothing 236 */ 237 void queue_remove_all_target(Queue_t *queue, int target) 238 { 239 unsigned long flags; 240 struct list_head *l; 241 242 spin_lock_irqsave(&queue->queue_lock, flags); 243 list_for_each(l, &queue->head) { 244 QE_t *q = list_entry(l, QE_t, list); 245 if (q->SCpnt->device->id == target) 246 __queue_remove(queue, l); 247 } 248 spin_unlock_irqrestore(&queue->queue_lock, flags); 249 } 250 251 /* 252 * Function: int queue_probetgtlun (queue, target, lun) 253 * Purpose : check to see if we have a command in the queue for the specified 254 * target/lun. 255 * Params : queue - queue to look in 256 * target - target we want to probe 257 * lun - lun on target 258 * Returns : 0 if not found, != 0 if found 259 */ 260 int queue_probetgtlun (Queue_t *queue, int target, int lun) 261 { 262 unsigned long flags; 263 struct list_head *l; 264 int found = 0; 265 266 spin_lock_irqsave(&queue->queue_lock, flags); 267 list_for_each(l, &queue->head) { 268 QE_t *q = list_entry(l, QE_t, list); 269 if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun) { 270 found = 1; 271 break; 272 } 273 } 274 spin_unlock_irqrestore(&queue->queue_lock, flags); 275 276 return found; 277 } 278 279 /* 280 * Function: int queue_remove_cmd(Queue_t *queue, struct scsi_cmnd *SCpnt) 281 * Purpose : remove a specific command from the queues 282 * Params : queue - queue to look in 283 * SCpnt - command to find 284 * Returns : 0 if not found 285 */ 286 int queue_remove_cmd(Queue_t *queue, struct scsi_cmnd *SCpnt) 287 { 288 unsigned long flags; 289 struct list_head *l; 290 int found = 0; 291 292 spin_lock_irqsave(&queue->queue_lock, flags); 293 list_for_each(l, &queue->head) { 294 QE_t *q = list_entry(l, QE_t, list); 295 if (q->SCpnt == SCpnt) { 296 __queue_remove(queue, l); 297 found = 1; 298 break; 299 } 300 } 301 spin_unlock_irqrestore(&queue->queue_lock, flags); 302 303 return found; 304 } 305 306 EXPORT_SYMBOL(queue_initialise); 307 EXPORT_SYMBOL(queue_free); 308 EXPORT_SYMBOL(__queue_add); 309 EXPORT_SYMBOL(queue_remove); 310 EXPORT_SYMBOL(queue_remove_exclude); 311 EXPORT_SYMBOL(queue_remove_tgtluntag); 312 EXPORT_SYMBOL(queue_remove_cmd); 313 EXPORT_SYMBOL(queue_remove_all_target); 314 EXPORT_SYMBOL(queue_probetgtlun); 315 316 MODULE_AUTHOR("Russell King"); 317 MODULE_DESCRIPTION("SCSI command queueing"); 318 MODULE_LICENSE("GPL"); 319