summaryrefslogtreecommitdiffstats
path: root/drivers/scsi/arm/queue.c
blob: cb11ccef54e5104d2825d4e6bfdfcefa8260672c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
/*
 *  linux/drivers/acorn/scsi/queue.c: queue handling primitives
 *
 *  Copyright (C) 1997-2000 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  Changelog:
 *   15-Sep-1997 RMK	Created.
 *   11-Oct-1997 RMK	Corrected problem with queue_remove_exclude
 *			not updating internal linked list properly
 *			(was causing commands to go missing).
 *   30-Aug-2000 RMK	Use Linux list handling and spinlocks
 */
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/init.h>

#include "../scsi.h"

#define DEBUG

typedef struct queue_entry {
	struct list_head   list;
	struct scsi_cmnd   *SCpnt;
#ifdef DEBUG
	unsigned long	   magic;
#endif
} QE_t;

#ifdef DEBUG
#define QUEUE_MAGIC_FREE	0xf7e1c9a3
#define QUEUE_MAGIC_USED	0xf7e1cc33

#define SET_MAGIC(q,m)	((q)->magic = (m))
#define BAD_MAGIC(q,m)	((q)->magic != (m))
#else
#define SET_MAGIC(q,m)	do { } while (0)
#define BAD_MAGIC(q,m)	(0)
#endif

#include "queue.h"

#define NR_QE	32

/*
 * Function: void queue_initialise (Queue_t *queue)
 * Purpose : initialise a queue
 * Params  : queue - queue to initialise
 */
int queue_initialise (Queue_t *queue)
{
	unsigned int nqueues = NR_QE;
	QE_t *q;

	spin_lock_init(&queue->queue_lock);
	INIT_LIST_HEAD(&queue->head);
	INIT_LIST_HEAD(&queue->free);

	/*
	 * If life was easier, then SCpnt would have a
	 * host-available list head, and we wouldn't
	 * need to keep free lists or allocate this
	 * memory.
	 */
	queue->alloc = q = kmalloc(sizeof(QE_t) * nqueues, GFP_KERNEL);
	if (q) {
		for (; nqueues; q++, nqueues--) {
			SET_MAGIC(q, QUEUE_MAGIC_FREE);
			q->SCpnt = NULL;
			list_add(&q->list, &queue->free);
		}
	}

	return queue->alloc != NULL;
}

/*
 * Function: void queue_free (Queue_t *queue)
 * Purpose : free a queue
 * Params  : queue - queue to free
 */
void queue_free (Queue_t *queue)
{
	if (!list_empty(&queue->head))
		printk(KERN_WARNING "freeing non-empty queue %p\n", queue);
	kfree(queue->alloc);
}
     

/*
 * Function: int __queue_add(Queue_t *queue, struct scsi_cmnd *SCpnt, int head)
 * Purpose : Add a new command onto a queue, adding REQUEST_SENSE to head.
 * Params  : queue - destination queue
 *	     SCpnt - command to add
 *	     head  - add command to head of queue
 * Returns : 0 on error, !0 on success
 */
int __queue_add(Queue_t *queue, struct scsi_cmnd *SCpnt, int head)
{
	unsigned long flags;
	struct list_head *l;
	QE_t *q;
	int ret = 0;

	spin_lock_irqsave(&queue->queue_lock, flags);
	if (list_empty(&queue->free))
		goto empty;

	l = queue->free.next;
	list_del(l);

	q = list_entry(l, QE_t, list);
	BUG_ON(BAD_MAGIC(q, QUEUE_MAGIC_FREE));

	SET_MAGIC(q, QUEUE_MAGIC_USED);
	q->SCpnt = SCpnt;

	if (head)
		list_add(l, &queue->head);
	else
		list_add_tail(l, &queue->head);

	ret = 1;
empty:
	spin_unlock_irqrestore(&queue->queue_lock, flags);
	return ret;
}

static struct scsi_cmnd *__queue_remove(Queue_t *queue, struct list_head *ent)
{
	QE_t *q;

	/*
	 * Move the entry from the "used" list onto the "free" list
	 */
	list_del(ent);
	q = list_entry(ent, QE_t, list);
	BUG_ON(BAD_MAGIC(q, QUEUE_MAGIC_USED));

	SET_MAGIC(q, QUEUE_MAGIC_FREE);
	list_add(ent, &queue->free);

	return q->SCpnt;
}

/*
 * Function: struct scsi_cmnd *queue_remove_exclude (queue, exclude)
 * Purpose : remove a SCSI command from a queue
 * Params  : queue   - queue to remove command from
 *	     exclude - bit array of target&lun which is busy
 * Returns : struct scsi_cmnd if successful (and a reference), or NULL if no command available
 */
struct scsi_cmnd *queue_remove_exclude(Queue_t *queue, unsigned long *exclude)
{
	unsigned long flags;
	struct list_head *l;
	struct scsi_cmnd *SCpnt = NULL;

	spin_lock_irqsave(&queue->queue_lock, flags);
	list_for_each(l, &queue->head) {
		QE_t *q = list_entry(l, QE_t, list);
		if (!test_bit(q->SCpnt->device->id * 8 + q->SCpnt->device->lun, exclude)) {
			SCpnt = __queue_remove(queue, l);
			break;
		}
	}
	spin_unlock_irqrestore(&queue->queue_lock, flags);

	return SCpnt;
}

/*
 * Function: struct scsi_cmnd *queue_remove (queue)
 * Purpose : removes first SCSI command from a queue
 * Params  : queue   - queue to remove command from
 * Returns : struct scsi_cmnd if successful (and a reference), or NULL if no command available
 */
struct scsi_cmnd *queue_remove(Queue_t *queue)
{
	unsigned long flags;
	struct scsi_cmnd *SCpnt = NULL;

	spin_lock_irqsave(&queue->queue_lock, flags);
	if (!list_empty(&queue->head))
		SCpnt = __queue_remove(queue, queue->head.next);
	spin_unlock_irqrestore(&queue->queue_lock, flags);

	return SCpnt;
}

/*
 * Function: struct scsi_cmnd *queue_remove_tgtluntag (queue, target, lun, tag)
 * Purpose : remove a SCSI command from the queue for a specified target/lun/tag
 * Params  : queue  - queue to remove command from
 *	     target - target that we want
 *	     lun    - lun on device
 *	     tag    - tag on device
 * Returns : struct scsi_cmnd if successful, or NULL if no command satisfies requirements
 */
struct scsi_cmnd *queue_remove_tgtluntag(Queue_t *queue, int target, int lun,
					 int tag)
{
	unsigned long flags;
	struct list_head *l;
	struct scsi_cmnd *SCpnt = NULL;

	spin_lock_irqsave(&queue->queue_lock, flags);
	list_for_each(l, &queue->head) {
		QE_t *q = list_entry(l, QE_t, list);
		if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun &&
		    q->SCpnt->tag == tag) {
			SCpnt = __queue_remove(queue, l);
			break;
		}
	}
	spin_unlock_irqrestore(&queue->queue_lock, flags);

	return SCpnt;
}

/*
 * Function: queue_remove_all_target(queue, target)
 * Purpose : remove all SCSI commands from the queue for a specified target
 * Params  : queue  - queue to remove command from
 *           target - target device id
 * Returns : nothing
 */
void queue_remove_all_target(Queue_t *queue, int target)
{
	unsigned long flags;
	struct list_head *l;

	spin_lock_irqsave(&queue->queue_lock, flags);
	list_for_each(l, &queue->head) {
		QE_t *q = list_entry(l, QE_t, list);
		if (q->SCpnt->device->id == target)
			__queue_remove(queue, l);
	}
	spin_unlock_irqrestore(&queue->queue_lock, flags);
}

/*
 * Function: int queue_probetgtlun (queue, target, lun)
 * Purpose : check to see if we have a command in the queue for the specified
 *	     target/lun.
 * Params  : queue  - queue to look in
 *	     target - target we want to probe
 *	     lun    - lun on target
 * Returns : 0 if not found, != 0 if found
 */
int queue_probetgtlun (Queue_t *queue, int target, int lun)
{
	unsigned long flags;
	struct list_head *l;
	int found = 0;

	spin_lock_irqsave(&queue->queue_lock, flags);
	list_for_each(l, &queue->head) {
		QE_t *q = list_entry(l, QE_t, list);
		if (q->SCpnt->device->id == target && q->SCpnt->device->lun == lun) {
			found = 1;
			break;
		}
	}
	spin_unlock_irqrestore(&queue->queue_lock, flags);

	return found;
}

/*
 * Function: int queue_remove_cmd(Queue_t *queue, struct scsi_cmnd *SCpnt)
 * Purpose : remove a specific command from the queues
 * Params  : queue - queue to look in
 *	     SCpnt - command to find
 * Returns : 0 if not found
 */
int queue_remove_cmd(Queue_t *queue, struct scsi_cmnd *SCpnt)
{
	unsigned long flags;
	struct list_head *l;
	int found = 0;

	spin_lock_irqsave(&queue->queue_lock, flags);
	list_for_each(l, &queue->head) {
		QE_t *q = list_entry(l, QE_t, list);
		if (q->SCpnt == SCpnt) {
			__queue_remove(queue, l);
			found = 1;
			break;
		}
	}
	spin_unlock_irqrestore(&queue->queue_lock, flags);

	return found;
}

EXPORT_SYMBOL(queue_initialise);
EXPORT_SYMBOL(queue_free);
EXPORT_SYMBOL(__queue_add);
EXPORT_SYMBOL(queue_remove);
EXPORT_SYMBOL(queue_remove_exclude);
EXPORT_SYMBOL(queue_remove_tgtluntag);
EXPORT_SYMBOL(queue_remove_cmd);
EXPORT_SYMBOL(queue_remove_all_target);
EXPORT_SYMBOL(queue_probetgtlun);

MODULE_AUTHOR("Russell King");
MODULE_DESCRIPTION("SCSI command queueing");
MODULE_LICENSE("GPL");
OpenPOWER on IntegriCloud