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/scsi.h> 24 #include <scsi/scsi_cmnd.h> 25 #include <scsi/scsi_device.h> 26 #include <scsi/scsi_eh.h> 27 #include <scsi/scsi_tcq.h> 28 29 #define DEBUG 30 31 typedef struct queue_entry { 32 struct list_head list; 33 struct scsi_cmnd *SCpnt; 34 #ifdef DEBUG 35 unsigned long magic; 36 #endif 37 } QE_t; 38 39 #ifdef DEBUG 40 #define QUEUE_MAGIC_FREE 0xf7e1c9a3 41 #define QUEUE_MAGIC_USED 0xf7e1cc33 42 43 #define SET_MAGIC(q,m) ((q)->magic = (m)) 44 #define BAD_MAGIC(q,m) ((q)->magic != (m)) 45 #else 46 #define SET_MAGIC(q,m) do { } while (0) 47 #define BAD_MAGIC(q,m) (0) 48 #endif 49 50 #include "queue.h" 51 52 #define NR_QE 32 53 54 /* 55 * Function: void queue_initialise (Queue_t *queue) 56 * Purpose : initialise a queue 57 * Params : queue - queue to initialise 58 */ 59 int queue_initialise (Queue_t *queue) 60 { 61 unsigned int nqueues = NR_QE; 62 QE_t *q; 63 64 spin_lock_init(&queue->queue_lock); 65 INIT_LIST_HEAD(&queue->head); 66 INIT_LIST_HEAD(&queue->free); 67 68 /* 69 * If life was easier, then SCpnt would have a 70 * host-available list head, and we wouldn't 71 * need to keep free lists or allocate this 72 * memory. 73 */ 74 queue->alloc = q = kmalloc_array(nqueues, sizeof(QE_t), GFP_KERNEL); 75 if (q) { 76 for (; nqueues; q++, nqueues--) { 77 SET_MAGIC(q, QUEUE_MAGIC_FREE); 78 q->SCpnt = NULL; 79 list_add(&q->list, &queue->free); 80 } 81 } 82 83 return queue->alloc != NULL; 84 } 85 86 /* 87 * Function: void queue_free (Queue_t *queue) 88 * Purpose : free a queue 89 * Params : queue - queue to free 90 */ 91 void queue_free (Queue_t *queue) 92 { 93 if (!list_empty(&queue->head)) 94 printk(KERN_WARNING "freeing non-empty queue %p\n", queue); 95 kfree(queue->alloc); 96 } 97 98 99 /* 100 * Function: int __queue_add(Queue_t *queue, struct 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, struct 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 BUG_ON(BAD_MAGIC(q, QUEUE_MAGIC_FREE)); 123 124 SET_MAGIC(q, QUEUE_MAGIC_USED); 125 q->SCpnt = SCpnt; 126 127 if (head) 128 list_add(l, &queue->head); 129 else 130 list_add_tail(l, &queue->head); 131 132 ret = 1; 133 empty: 134 spin_unlock_irqrestore(&queue->queue_lock, flags); 135 return ret; 136 } 137 138 static struct scsi_cmnd *__queue_remove(Queue_t *queue, struct list_head *ent) 139 { 140 QE_t *q; 141 142 /* 143 * Move the entry from the "used" list onto the "free" list 144 */ 145 list_del(ent); 146 q = list_entry(ent, QE_t, list); 147 BUG_ON(BAD_MAGIC(q, QUEUE_MAGIC_USED)); 148 149 SET_MAGIC(q, QUEUE_MAGIC_FREE); 150 list_add(ent, &queue->free); 151 152 return q->SCpnt; 153 } 154 155 /* 156 * Function: struct scsi_cmnd *queue_remove_exclude (queue, exclude) 157 * Purpose : remove a SCSI command from a queue 158 * Params : queue - queue to remove command from 159 * exclude - bit array of target&lun which is busy 160 * Returns : struct scsi_cmnd if successful (and a reference), or NULL if no command available 161 */ 162 struct scsi_cmnd *queue_remove_exclude(Queue_t *queue, unsigned long *exclude) 163 { 164 unsigned long flags; 165 struct list_head *l; 166 struct scsi_cmnd *SCpnt = NULL; 167 168 spin_lock_irqsave(&queue->queue_lock, flags); 169 list_for_each(l, &queue->head) { 170 QE_t *q = list_entry(l, QE_t, list); 171 if (!test_bit(q->SCpnt->device->id * 8 + 172 (u8)(q->SCpnt->device->lun & 0x7), exclude)) { 173 SCpnt = __queue_remove(queue, l); 174 break; 175 } 176 } 177 spin_unlock_irqrestore(&queue->queue_lock, flags); 178 179 return SCpnt; 180 } 181 182 /* 183 * Function: struct scsi_cmnd *queue_remove (queue) 184 * Purpose : removes first SCSI command from a queue 185 * Params : queue - queue to remove command from 186 * Returns : struct scsi_cmnd if successful (and a reference), or NULL if no command available 187 */ 188 struct scsi_cmnd *queue_remove(Queue_t *queue) 189 { 190 unsigned long flags; 191 struct scsi_cmnd *SCpnt = NULL; 192 193 spin_lock_irqsave(&queue->queue_lock, flags); 194 if (!list_empty(&queue->head)) 195 SCpnt = __queue_remove(queue, queue->head.next); 196 spin_unlock_irqrestore(&queue->queue_lock, flags); 197 198 return SCpnt; 199 } 200 201 /* 202 * Function: struct scsi_cmnd *queue_remove_tgtluntag (queue, target, lun, tag) 203 * Purpose : remove a SCSI command from the queue for a specified target/lun/tag 204 * Params : queue - queue to remove command from 205 * target - target that we want 206 * lun - lun on device 207 * tag - tag on device 208 * Returns : struct scsi_cmnd if successful, or NULL if no command satisfies requirements 209 */ 210 struct scsi_cmnd *queue_remove_tgtluntag(Queue_t *queue, int target, int lun, 211 int tag) 212 { 213 unsigned long flags; 214 struct list_head *l; 215 struct 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 scsi_cmd_to_rq(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, struct 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, struct 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