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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
31typedef 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 */
59int 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_objs(QE_t, nqueues);
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 */
91void 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 */
107int __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;
133empty:
134 spin_unlock_irqrestore(&queue->queue_lock, flags);
135 return ret;
136}
137
138static 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 */
162struct 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 */
188struct 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 */
210struct 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 */
238void 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 */
261int 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 */
287int 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
307EXPORT_SYMBOL(queue_initialise);
308EXPORT_SYMBOL(queue_free);
309EXPORT_SYMBOL(__queue_add);
310EXPORT_SYMBOL(queue_remove);
311EXPORT_SYMBOL(queue_remove_exclude);
312EXPORT_SYMBOL(queue_remove_tgtluntag);
313EXPORT_SYMBOL(queue_remove_cmd);
314EXPORT_SYMBOL(queue_remove_all_target);
315EXPORT_SYMBOL(queue_probetgtlun);
316
317MODULE_AUTHOR("Russell King");
318MODULE_DESCRIPTION("SCSI command queueing");
319MODULE_LICENSE("GPL");