summaryrefslogtreecommitdiffstats
path: root/lib/parman.c
blob: a11f2f667639725d927566185b5f40b336d5a754 (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
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
/*
 * lib/parman.c - Manager for linear priority array areas
 * Copyright (c) 2017 Mellanox Technologies. All rights reserved.
 * Copyright (c) 2017 Jiri Pirko <jiri@mellanox.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/list.h>
#include <linux/err.h>
#include <linux/parman.h>

struct parman_algo {
	int (*item_add)(struct parman *parman, struct parman_prio *prio,
			struct parman_item *item);
	void (*item_remove)(struct parman *parman, struct parman_prio *prio,
			    struct parman_item *item);
};

struct parman {
	const struct parman_ops *ops;
	void *priv;
	const struct parman_algo *algo;
	unsigned long count;
	unsigned long limit_count;
	struct list_head prio_list;
};

static int parman_enlarge(struct parman *parman)
{
	unsigned long new_count = parman->limit_count +
				  parman->ops->resize_step;
	int err;

	err = parman->ops->resize(parman->priv, new_count);
	if (err)
		return err;
	parman->limit_count = new_count;
	return 0;
}

static int parman_shrink(struct parman *parman)
{
	unsigned long new_count = parman->limit_count -
				  parman->ops->resize_step;
	int err;

	if (new_count < parman->ops->base_count)
		return 0;
	err = parman->ops->resize(parman->priv, new_count);
	if (err)
		return err;
	parman->limit_count = new_count;
	return 0;
}

static bool parman_prio_used(struct parman_prio *prio)
{
	return !list_empty(&prio->item_list);
}

static struct parman_item *parman_prio_first_item(struct parman_prio *prio)
{
	return list_first_entry(&prio->item_list,
				typeof(struct parman_item), list);
}

static unsigned long parman_prio_first_index(struct parman_prio *prio)
{
	return parman_prio_first_item(prio)->index;
}

static struct parman_item *parman_prio_last_item(struct parman_prio *prio)
{
	return list_last_entry(&prio->item_list,
			       typeof(struct parman_item), list);
}

static unsigned long parman_prio_last_index(struct parman_prio *prio)
{
	return parman_prio_last_item(prio)->index;
}

static unsigned long parman_lsort_new_index_find(struct parman *parman,
						 struct parman_prio *prio)
{
	list_for_each_entry_from_reverse(prio, &parman->prio_list, list) {
		if (!parman_prio_used(prio))
			continue;
		return parman_prio_last_index(prio) + 1;
	}
	return 0;
}

static void __parman_prio_move(struct parman *parman, struct parman_prio *prio,
			       struct parman_item *item, unsigned long to_index,
			       unsigned long count)
{
	parman->ops->move(parman->priv, item->index, to_index, count);
}

static void parman_prio_shift_down(struct parman *parman,
				   struct parman_prio *prio)
{
	struct parman_item *item;
	unsigned long to_index;

	if (!parman_prio_used(prio))
		return;
	item = parman_prio_first_item(prio);
	to_index = parman_prio_last_index(prio) + 1;
	__parman_prio_move(parman, prio, item, to_index, 1);
	list_move_tail(&item->list, &prio->item_list);
	item->index = to_index;
}

static void parman_prio_shift_up(struct parman *parman,
				 struct parman_prio *prio)
{
	struct parman_item *item;
	unsigned long to_index;

	if (!parman_prio_used(prio))
		return;
	item = parman_prio_last_item(prio);
	to_index = parman_prio_first_index(prio) - 1;
	__parman_prio_move(parman, prio, item, to_index, 1);
	list_move(&item->list, &prio->item_list);
	item->index = to_index;
}

static void parman_prio_item_remove(struct parman *parman,
				    struct parman_prio *prio,
				    struct parman_item *item)
{
	struct parman_item *last_item;
	unsigned long to_index;

	last_item = parman_prio_last_item(prio);
	if (last_item == item) {
		list_del(&item->list);
		return;
	}
	to_index = item->index;
	__parman_prio_move(parman, prio, last_item, to_index, 1);
	list_del(&last_item->list);
	list_replace(&item->list, &last_item->list);
	last_item->index = to_index;
}

static int parman_lsort_item_add(struct parman *parman,
				 struct parman_prio *prio,
				 struct parman_item *item)
{
	struct parman_prio *prio2;
	unsigned long new_index;
	int err;

	if (parman->count + 1 > parman->limit_count) {
		err = parman_enlarge(parman);
		if (err)
			return err;
	}

	new_index = parman_lsort_new_index_find(parman, prio);
	list_for_each_entry_reverse(prio2, &parman->prio_list, list) {
		if (prio2 == prio)
			break;
		parman_prio_shift_down(parman, prio2);
	}
	item->index = new_index;
	list_add_tail(&item->list, &prio->item_list);
	parman->count++;
	return 0;
}

static void parman_lsort_item_remove(struct parman *parman,
				     struct parman_prio *prio,
				     struct parman_item *item)
{
	parman_prio_item_remove(parman, prio, item);
	list_for_each_entry_continue(prio, &parman->prio_list, list)
		parman_prio_shift_up(parman, prio);
	parman->count--;
	if (parman->limit_count - parman->count >= parman->ops->resize_step)
		parman_shrink(parman);
}

static const struct parman_algo parman_lsort = {
	.item_add	= parman_lsort_item_add,
	.item_remove	= parman_lsort_item_remove,
};

static const struct parman_algo *parman_algos[] = {
	&parman_lsort,
};

/**
 * parman_create - creates a new parman instance
 * @ops:	caller-specific callbacks
 * @priv:	pointer to a private data passed to the ops
 *
 * Note: all locking must be provided by the caller.
 *
 * Each parman instance manages an array area with chunks of entries
 * with the same priority. Consider following example:
 *
 * item 1 with prio 10
 * item 2 with prio 10
 * item 3 with prio 10
 * item 4 with prio 20
 * item 5 with prio 20
 * item 6 with prio 30
 * item 7 with prio 30
 * item 8 with prio 30
 *
 * In this example, there are 3 priority chunks. The order of the priorities
 * matters, however the order of items within a single priority chunk does not
 * matter. So the same array could be ordered as follows:
 *
 * item 2 with prio 10
 * item 3 with prio 10
 * item 1 with prio 10
 * item 5 with prio 20
 * item 4 with prio 20
 * item 7 with prio 30
 * item 8 with prio 30
 * item 6 with prio 30
 *
 * The goal of parman is to maintain the priority ordering. The caller
 * provides @ops with callbacks parman uses to move the items
 * and resize the array area.
 *
 * Returns a pointer to newly created parman instance in case of success,
 * otherwise it returns NULL.
 */
struct parman *parman_create(const struct parman_ops *ops, void *priv)
{
	struct parman *parman;

	parman = kzalloc(sizeof(*parman), GFP_KERNEL);
	if (!parman)
		return NULL;
	INIT_LIST_HEAD(&parman->prio_list);
	parman->ops = ops;
	parman->priv = priv;
	parman->limit_count = ops->base_count;
	parman->algo = parman_algos[ops->algo];
	return parman;
}
EXPORT_SYMBOL(parman_create);

/**
 * parman_destroy - destroys existing parman instance
 * @parman:	parman instance
 *
 * Note: all locking must be provided by the caller.
 */
void parman_destroy(struct parman *parman)
{
	WARN_ON(!list_empty(&parman->prio_list));
	kfree(parman);
}
EXPORT_SYMBOL(parman_destroy);

/**
 * parman_prio_init - initializes a parman priority chunk
 * @parman:	parman instance
 * @prio:	parman prio structure to be initialized
 * @prority:	desired priority of the chunk
 *
 * Note: all locking must be provided by the caller.
 *
 * Before caller could add an item with certain priority, he has to
 * initialize a priority chunk for it using this function.
 */
void parman_prio_init(struct parman *parman, struct parman_prio *prio,
		      unsigned long priority)
{
	struct parman_prio *prio2;
	struct list_head *pos;

	INIT_LIST_HEAD(&prio->item_list);
	prio->priority = priority;

	/* Position inside the list according to priority */
	list_for_each(pos, &parman->prio_list) {
		prio2 = list_entry(pos, typeof(*prio2), list);
		if (prio2->priority > prio->priority)
			break;
	}
	list_add_tail(&prio->list, pos);
}
EXPORT_SYMBOL(parman_prio_init);

/**
 * parman_prio_fini - finalizes use of parman priority chunk
 * @prio:	parman prio structure
 *
 * Note: all locking must be provided by the caller.
 */
void parman_prio_fini(struct parman_prio *prio)
{
	WARN_ON(parman_prio_used(prio));
	list_del(&prio->list);
}
EXPORT_SYMBOL(parman_prio_fini);

/**
 * parman_item_add - adds a parman item under defined priority
 * @parman:	parman instance
 * @prio:	parman prio instance to add the item to
 * @item:	parman item instance
 *
 * Note: all locking must be provided by the caller.
 *
 * Adds item to a array managed by parman instance under the specified priority.
 *
 * Returns 0 in case of success, negative number to indicate an error.
 */
int parman_item_add(struct parman *parman, struct parman_prio *prio,
		    struct parman_item *item)
{
	return parman->algo->item_add(parman, prio, item);
}
EXPORT_SYMBOL(parman_item_add);

/**
 * parman_item_del - deletes parman item
 * @parman:	parman instance
 * @prio:	parman prio instance to delete the item from
 * @item:	parman item instance
 *
 * Note: all locking must be provided by the caller.
 */
void parman_item_remove(struct parman *parman, struct parman_prio *prio,
			struct parman_item *item)
{
	parman->algo->item_remove(parman, prio, item);
}
EXPORT_SYMBOL(parman_item_remove);

MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Jiri Pirko <jiri@mellanox.com>");
MODULE_DESCRIPTION("Priority-based array manager");