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 */
queue_initialise(Queue_t * queue)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 */
queue_free(Queue_t * queue)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 */
__queue_add(Queue_t * queue,struct scsi_cmnd * SCpnt,int head)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
__queue_remove(Queue_t * queue,struct list_head * ent)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 */
queue_remove_exclude(Queue_t * queue,unsigned long * exclude)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 */
queue_remove(Queue_t * queue)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 */
queue_remove_tgtluntag(Queue_t * queue,int target,int lun,int tag)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 */
queue_remove_all_target(Queue_t * queue,int target)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 */
queue_probetgtlun(Queue_t * queue,int target,int lun)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 */
queue_remove_cmd(Queue_t * queue,struct scsi_cmnd * SCpnt)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
