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"); 316