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/blk.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/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 */
queue_initialise(Queue_t * queue)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 */
queue_free(Queue_t * queue)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 */
__queue_add(Queue_t * queue,Scsi_Cmnd * SCpnt,int head)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
__queue_remove(Queue_t * queue,struct list_head * ent)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 */
queue_remove_exclude(Queue_t * queue,void * exclude)164 Scsi_Cmnd *queue_remove_exclude(Queue_t *queue, void *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->target * 8 + q->SCpnt->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 */
queue_remove(Queue_t * queue)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 */
queue_remove_tgtluntag(Queue_t * queue,int target,int lun,int tag)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->target == target && q->SCpnt->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 */
queue_remove_all_target(Queue_t * queue,int target)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->target == 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 */
queue_probetgtlun(Queue_t * queue,int target,int lun)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->target == target && q->SCpnt->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 */
queue_remove_cmd(Queue_t * queue,Scsi_Cmnd * SCpnt)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