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 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_cmd(Queue_t *queue, 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, 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 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: 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 : Scsi_Cmnd if successful (and a reference), or NULL if no command available 160 */ 161 Scsi_Cmnd *queue_remove_exclude(Queue_t *queue, unsigned long *exclude) 162 { 163 unsigned long flags; 164 struct list_head *l; 165 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: Scsi_Cmnd *queue_remove (queue) 182 * Purpose : removes first SCSI command from a queue 183 * Params : queue - queue to remove command from 184 * Returns : Scsi_Cmnd if successful (and a reference), or NULL if no command available 185 */ 186 Scsi_Cmnd *queue_remove(Queue_t *queue) 187 { 188 unsigned long flags; 189 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: 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 : Scsi_Cmnd if successful, or NULL if no command satisfies requirements 207 */ 208 Scsi_Cmnd *queue_remove_tgtluntag (Queue_t *queue, int target, int lun, int tag) 209 { 210 unsigned long flags; 211 struct list_head *l; 212 Scsi_Cmnd *SCpnt = NULL; 213 214 spin_lock_irqsave(&queue->queue_lock, flags); 215 list_for_each(l, &queue->head) { 216 QE_t *q = list_entry(l, QE_t, list); 217 if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun && 218 q->SCpnt->tag == tag) { 219 SCpnt = __queue_remove(queue, l); 220 break; 221 } 222 } 223 spin_unlock_irqrestore(&queue->queue_lock, flags); 224 225 return SCpnt; 226 } 227 228 /* 229 * Function: queue_remove_all_target(queue, target) 230 * Purpose : remove all SCSI commands from the queue for a specified target 231 * Params : queue - queue to remove command from 232 * target - target device id 233 * Returns : nothing 234 */ 235 void queue_remove_all_target(Queue_t *queue, int target) 236 { 237 unsigned long flags; 238 struct list_head *l; 239 240 spin_lock_irqsave(&queue->queue_lock, flags); 241 list_for_each(l, &queue->head) { 242 QE_t *q = list_entry(l, QE_t, list); 243 if (q->SCpnt->device->id == target) 244 __queue_remove(queue, l); 245 } 246 spin_unlock_irqrestore(&queue->queue_lock, flags); 247 } 248 249 /* 250 * Function: int queue_probetgtlun (queue, target, lun) 251 * Purpose : check to see if we have a command in the queue for the specified 252 * target/lun. 253 * Params : queue - queue to look in 254 * target - target we want to probe 255 * lun - lun on target 256 * Returns : 0 if not found, != 0 if found 257 */ 258 int queue_probetgtlun (Queue_t *queue, int target, int lun) 259 { 260 unsigned long flags; 261 struct list_head *l; 262 int found = 0; 263 264 spin_lock_irqsave(&queue->queue_lock, flags); 265 list_for_each(l, &queue->head) { 266 QE_t *q = list_entry(l, QE_t, list); 267 if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun) { 268 found = 1; 269 break; 270 } 271 } 272 spin_unlock_irqrestore(&queue->queue_lock, flags); 273 274 return found; 275 } 276 277 /* 278 * Function: int queue_remove_cmd(Queue_t *queue, Scsi_Cmnd *SCpnt) 279 * Purpose : remove a specific command from the queues 280 * Params : queue - queue to look in 281 * SCpnt - command to find 282 * Returns : 0 if not found 283 */ 284 int queue_remove_cmd(Queue_t *queue, Scsi_Cmnd *SCpnt) 285 { 286 unsigned long flags; 287 struct list_head *l; 288 int found = 0; 289 290 spin_lock_irqsave(&queue->queue_lock, flags); 291 list_for_each(l, &queue->head) { 292 QE_t *q = list_entry(l, QE_t, list); 293 if (q->SCpnt == SCpnt) { 294 __queue_remove(queue, l); 295 found = 1; 296 break; 297 } 298 } 299 spin_unlock_irqrestore(&queue->queue_lock, flags); 300 301 return found; 302 } 303 304 EXPORT_SYMBOL(queue_initialise); 305 EXPORT_SYMBOL(queue_free); 306 EXPORT_SYMBOL(__queue_add); 307 EXPORT_SYMBOL(queue_remove); 308 EXPORT_SYMBOL(queue_remove_exclude); 309 EXPORT_SYMBOL(queue_remove_tgtluntag); 310 EXPORT_SYMBOL(queue_remove_cmd); 311 EXPORT_SYMBOL(queue_remove_all_target); 312 EXPORT_SYMBOL(queue_probetgtlun); 313 314 MODULE_AUTHOR("Russell King"); 315 MODULE_DESCRIPTION("SCSI command queueing"); 316 MODULE_LICENSE("GPL"); 317