xref: /freebsd/sys/net/route/nhop_utils.c (revision cab6a39d7b343596a5823e65c0f7b426551ec22d)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2020 Alexander V. Chernikov
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25  * SUCH DAMAGE.
26  */
27 
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
30 #include "opt_inet.h"
31 #include "opt_route.h"
32 
33 #include <sys/param.h>
34 #include <sys/systm.h>
35 #include <sys/lock.h>
36 #include <sys/malloc.h>
37 #include <sys/mbuf.h>
38 #include <sys/kernel.h>
39 
40 #include <net/route/nhop_utils.h>
41 
42 #define	BLOCK_ITEMS	(8 * sizeof(u_long))	/* Number of items for ffsl() */
43 
44 #define	_BLOCKS_TO_SZ(_blocks)		((size_t)(_blocks) * sizeof(u_long))
45 #define	_BLOCKS_TO_ITEMS(_blocks)	((uint32_t)(_blocks) * BLOCK_ITEMS)
46 #define	_ITEMS_TO_BLOCKS(_items)	((_items) / BLOCK_ITEMS)
47 
48 static void _bitmask_init_idx(void *index, uint32_t items);
49 
50 void
51 bitmask_init(struct bitmask_head *bh, void *idx, uint32_t num_items)
52 {
53 
54 	if (idx != NULL)
55 		_bitmask_init_idx(idx, num_items);
56 
57 	memset(bh, 0, sizeof(struct bitmask_head));
58 	bh->blocks = _ITEMS_TO_BLOCKS(num_items);
59 	bh->idx = (u_long *)idx;
60 }
61 
62 uint32_t
63 bitmask_get_resize_items(const struct bitmask_head *bh)
64 {
65 	if ((bh->items_count * 2 > _BLOCKS_TO_ITEMS(bh->blocks)) && bh->items_count < 65536)
66 		return (_BLOCKS_TO_ITEMS(bh->blocks) * 2);
67 
68 	return (0);
69 }
70 
71 int
72 bitmask_should_resize(const struct bitmask_head *bh)
73 {
74 
75 	return (bitmask_get_resize_items(bh) != 0);
76 }
77 
78 #if 0
79 uint32_t
80 _bitmask_get_blocks(uint32_t items)
81 {
82 
83 	return (items / BLOCK_ITEMS);
84 }
85 #endif
86 
87 size_t
88 bitmask_get_size(uint32_t items)
89 {
90 #if _KERNEL
91 	KASSERT((items % BLOCK_ITEMS) == 0,
92 	   ("bitmask size needs to power of 2 and greater or equal to %zu",
93 	    BLOCK_ITEMS));
94 #else
95 	assert((items % BLOCK_ITEMS) == 0);
96 #endif
97 
98 	return (items / 8);
99 }
100 
101 static void
102 _bitmask_init_idx(void *_idx, uint32_t items)
103 {
104 	size_t size = bitmask_get_size(items);
105 	u_long *idx = (u_long *)_idx;
106 
107 	/* Mark all as free */
108 	memset(idx, 0xFF, size);
109 	*idx &= ~(u_long)1; /* Always skip index 0 */
110 }
111 
112 /*
113  * _try_merge api to allow shrinking?
114  */
115 int
116 bitmask_copy(const struct bitmask_head *bi, void *new_idx, uint32_t new_items)
117 {
118 	uint32_t new_blocks = _BLOCKS_TO_ITEMS(new_items);
119 
120 	_bitmask_init_idx(new_idx, new_items);
121 
122 	if (bi->blocks < new_blocks) {
123 		/* extend current blocks */
124 		if (bi->blocks > 0)
125 			memcpy(new_idx, bi->idx, _BLOCKS_TO_SZ(bi->blocks));
126 		return (0);
127 	} else {
128 		/* XXX: ensure all other blocks are non-zero */
129 		for (int i = new_blocks; i < bi->blocks; i++) {
130 		}
131 
132 		return (1);
133 	}
134 }
135 
136 void
137 bitmask_swap(struct bitmask_head *bh, void *new_idx, uint32_t new_items, void **pidx)
138 {
139 	void *old_ptr;
140 
141 	old_ptr = bh->idx;
142 
143 	bh->idx = (u_long *)new_idx;
144 	bh->blocks = _ITEMS_TO_BLOCKS(new_items);
145 
146 	if (pidx != NULL)
147 		*pidx = old_ptr;
148 }
149 
150 /*
151  * Allocate new index in given instance and stores in in @pidx.
152  * Returns 0 on success.
153  */
154 int
155 bitmask_alloc_idx(struct bitmask_head *bi, uint16_t *pidx)
156 {
157 	u_long *mask;
158 	int i, off, v;
159 
160 	off = bi->free_off;
161 	mask = &bi->idx[off];
162 
163 	for (i = off; i < bi->blocks; i++, mask++) {
164 		if ((v = ffsl(*mask)) == 0)
165 			continue;
166 
167 		/* Mark as busy */
168 		*mask &= ~ ((u_long)1 << (v - 1));
169 
170 		bi->free_off = i;
171 
172 		v = BLOCK_ITEMS * i + v - 1;
173 
174 		*pidx = v;
175 		bi->items_count++;
176 		return (0);
177 	}
178 
179 	return (1);
180 }
181 
182 /*
183  * Removes index from given set.
184  * Returns 0 on success.
185  */
186 int
187 bitmask_free_idx(struct bitmask_head *bi, uint16_t idx)
188 {
189 	u_long *mask;
190 	int i, v;
191 
192 	if (idx == 0)
193 		return (1);
194 
195 	i = idx / BLOCK_ITEMS;
196 	v = idx % BLOCK_ITEMS;
197 
198 	if (i >= bi->blocks)
199 		return (1);
200 
201 	mask = &bi->idx[i];
202 
203 	if ((*mask & ((u_long)1 << v)) != 0)
204 		return (1);
205 
206 	/* Mark as free */
207 	*mask |= (u_long)1 << v;
208 	bi->items_count--;
209 
210 	/* Update free offset */
211 	if (bi->free_off > i)
212 		bi->free_off = i;
213 
214 	return (0);
215 }
216