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