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 if (queue->alloc) 95 kfree(queue->alloc); 96 } 97 98 99 /* 100 * Function: int queue_add_cmd(Queue_t *queue, Scsi_Cmnd *SCpnt, int head) 101 * Purpose : Add a new command onto a queue, adding REQUEST_SENSE to head. 102 * Params : queue - destination queue 103 * SCpnt - command to add 104 * head - add command to head of queue 105 * Returns : 0 on error, !0 on success 106 */ 107 int __queue_add(Queue_t *queue, Scsi_Cmnd *SCpnt, int head) 108 { 109 unsigned long flags; 110 struct list_head *l; 111 QE_t *q; 112 int ret = 0; 113 114 spin_lock_irqsave(&queue->queue_lock, flags); 115 if (list_empty(&queue->free)) 116 goto empty; 117 118 l = queue->free.next; 119 list_del(l); 120 121 q = list_entry(l, QE_t, list); 122 if (BAD_MAGIC(q, QUEUE_MAGIC_FREE)) 123 BUG(); 124 125 SET_MAGIC(q, QUEUE_MAGIC_USED); 126 q->SCpnt = SCpnt; 127 128 if (head) 129 list_add(l, &queue->head); 130 else 131 list_add_tail(l, &queue->head); 132 133 ret = 1; 134 empty: 135 spin_unlock_irqrestore(&queue->queue_lock, flags); 136 return ret; 137 } 138 139 static Scsi_Cmnd *__queue_remove(Queue_t *queue, struct list_head *ent) 140 { 141 QE_t *q; 142 143 /* 144 * Move the entry from the "used" list onto the "free" list 145 */ 146 list_del(ent); 147 q = list_entry(ent, QE_t, list); 148 if (BAD_MAGIC(q, QUEUE_MAGIC_USED)) 149 BUG(); 150 151 SET_MAGIC(q, QUEUE_MAGIC_FREE); 152 list_add(ent, &queue->free); 153 154 return q->SCpnt; 155 } 156 157 /* 158 * Function: Scsi_Cmnd *queue_remove_exclude (queue, exclude) 159 * Purpose : remove a SCSI command from a queue 160 * Params : queue - queue to remove command from 161 * exclude - bit array of target&lun which is busy 162 * Returns : Scsi_Cmnd if successful (and a reference), or NULL if no command available 163 */ 164 Scsi_Cmnd *queue_remove_exclude(Queue_t *queue, unsigned long *exclude) 165 { 166 unsigned long flags; 167 struct list_head *l; 168 Scsi_Cmnd *SCpnt = NULL; 169 170 spin_lock_irqsave(&queue->queue_lock, flags); 171 list_for_each(l, &queue->head) { 172 QE_t *q = list_entry(l, QE_t, list); 173 if (!test_bit(q->SCpnt->device->id * 8 + q->SCpnt->device->lun, exclude)) { 174 SCpnt = __queue_remove(queue, l); 175 break; 176 } 177 } 178 spin_unlock_irqrestore(&queue->queue_lock, flags); 179 180 return SCpnt; 181 } 182 183 /* 184 * Function: Scsi_Cmnd *queue_remove (queue) 185 * Purpose : removes first SCSI command from a queue 186 * Params : queue - queue to remove command from 187 * Returns : Scsi_Cmnd if successful (and a reference), or NULL if no command available 188 */ 189 Scsi_Cmnd *queue_remove(Queue_t *queue) 190 { 191 unsigned long flags; 192 Scsi_Cmnd *SCpnt = NULL; 193 194 spin_lock_irqsave(&queue->queue_lock, flags); 195 if (!list_empty(&queue->head)) 196 SCpnt = __queue_remove(queue, queue->head.next); 197 spin_unlock_irqrestore(&queue->queue_lock, flags); 198 199 return SCpnt; 200 } 201 202 /* 203 * Function: Scsi_Cmnd *queue_remove_tgtluntag (queue, target, lun, tag) 204 * Purpose : remove a SCSI command from the queue for a specified target/lun/tag 205 * Params : queue - queue to remove command from 206 * target - target that we want 207 * lun - lun on device 208 * tag - tag on device 209 * Returns : Scsi_Cmnd if successful, or NULL if no command satisfies requirements 210 */ 211 Scsi_Cmnd *queue_remove_tgtluntag (Queue_t *queue, int target, int lun, int tag) 212 { 213 unsigned long flags; 214 struct list_head *l; 215 Scsi_Cmnd *SCpnt = NULL; 216 217 spin_lock_irqsave(&queue->queue_lock, flags); 218 list_for_each(l, &queue->head) { 219 QE_t *q = list_entry(l, QE_t, list); 220 if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun && 221 q->SCpnt->tag == tag) { 222 SCpnt = __queue_remove(queue, l); 223 break; 224 } 225 } 226 spin_unlock_irqrestore(&queue->queue_lock, flags); 227 228 return SCpnt; 229 } 230 231 /* 232 * Function: queue_remove_all_target(queue, target) 233 * Purpose : remove all SCSI commands from the queue for a specified target 234 * Params : queue - queue to remove command from 235 * target - target device id 236 * Returns : nothing 237 */ 238 void queue_remove_all_target(Queue_t *queue, int target) 239 { 240 unsigned long flags; 241 struct list_head *l; 242 243 spin_lock_irqsave(&queue->queue_lock, flags); 244 list_for_each(l, &queue->head) { 245 QE_t *q = list_entry(l, QE_t, list); 246 if (q->SCpnt->device->id == target) 247 __queue_remove(queue, l); 248 } 249 spin_unlock_irqrestore(&queue->queue_lock, flags); 250 } 251 252 /* 253 * Function: int queue_probetgtlun (queue, target, lun) 254 * Purpose : check to see if we have a command in the queue for the specified 255 * target/lun. 256 * Params : queue - queue to look in 257 * target - target we want to probe 258 * lun - lun on target 259 * Returns : 0 if not found, != 0 if found 260 */ 261 int queue_probetgtlun (Queue_t *queue, int target, int lun) 262 { 263 unsigned long flags; 264 struct list_head *l; 265 int found = 0; 266 267 spin_lock_irqsave(&queue->queue_lock, flags); 268 list_for_each(l, &queue->head) { 269 QE_t *q = list_entry(l, QE_t, list); 270 if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun) { 271 found = 1; 272 break; 273 } 274 } 275 spin_unlock_irqrestore(&queue->queue_lock, flags); 276 277 return found; 278 } 279 280 /* 281 * Function: int queue_remove_cmd(Queue_t *queue, Scsi_Cmnd *SCpnt) 282 * Purpose : remove a specific command from the queues 283 * Params : queue - queue to look in 284 * SCpnt - command to find 285 * Returns : 0 if not found 286 */ 287 int queue_remove_cmd(Queue_t *queue, Scsi_Cmnd *SCpnt) 288 { 289 unsigned long flags; 290 struct list_head *l; 291 int found = 0; 292 293 spin_lock_irqsave(&queue->queue_lock, flags); 294 list_for_each(l, &queue->head) { 295 QE_t *q = list_entry(l, QE_t, list); 296 if (q->SCpnt == SCpnt) { 297 __queue_remove(queue, l); 298 found = 1; 299 break; 300 } 301 } 302 spin_unlock_irqrestore(&queue->queue_lock, flags); 303 304 return found; 305 } 306 307 EXPORT_SYMBOL(queue_initialise); 308 EXPORT_SYMBOL(queue_free); 309 EXPORT_SYMBOL(__queue_add); 310 EXPORT_SYMBOL(queue_remove); 311 EXPORT_SYMBOL(queue_remove_exclude); 312 EXPORT_SYMBOL(queue_remove_tgtluntag); 313 EXPORT_SYMBOL(queue_remove_cmd); 314 EXPORT_SYMBOL(queue_remove_all_target); 315 EXPORT_SYMBOL(queue_probetgtlun); 316 317 MODULE_AUTHOR("Russell King"); 318 MODULE_DESCRIPTION("SCSI command queueing"); 319 MODULE_LICENSE("GPL"); 320