2 * Copyright (c) 2009 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Alex Hornung <ahornung@gmail.com>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/kernel.h>
37 #include <sys/types.h>
38 #include <machine/limits.h>
39 #include <sys/devfs.h>
41 MALLOC_DECLARE(M_DEVFS);
44 * DEVFS clone bitmap functions
47 devfs_clone_bitmap_init(struct devfs_bitmap *bitmap)
49 bitmap->chunks = DEVFS_BITMAP_INITIAL_SIZE;
50 bitmap->bitmap = kmalloc(bitmap->chunks * sizeof(u_long),
52 memset(bitmap->bitmap, -1, bitmap->chunks * sizeof(u_long));
57 devfs_clone_bitmap_uninit(struct devfs_bitmap *bitmap)
59 kfree(bitmap->bitmap, M_DEVFS);
63 * Extend the bitmap past (not just up to) 'newchunks' chunks. While
64 * probably not necessary, we go a little further and give ourselves
65 * one extra chunk's worth of bitmap beyond what is required.
68 devfs_clone_bitmap_extend(struct devfs_bitmap *bitmap, int newchunks)
70 int oldchunks = bitmap->chunks;
72 bitmap->chunks = newchunks + 2;
73 bitmap->bitmap = krealloc(bitmap->bitmap,
74 sizeof(u_long) * bitmap->chunks,
76 memset(bitmap->bitmap + oldchunks, -1,
77 sizeof(u_long) * (bitmap->chunks - oldchunks));
81 * This helper function determines the next available free unit in the
82 * bitmap, extending the bitmap if necessary. It cannot fail.
85 devfs_clone_bitmap_fff(struct devfs_bitmap *bitmap)
91 chunks = bitmap->chunks;
93 for (i = 0; i < chunks + 1; i++) {
95 devfs_clone_bitmap_extend(bitmap, i);
96 curbitmap = bitmap->bitmap[i];
99 curbitmap &= (~curbitmap)+1;
100 for (bit = 1; curbitmap != 1; bit++)
103 return (bit - 1 + (i << 3) * sizeof(curbitmap));
110 panic("devfs_clone_bitmap_fff");
115 * Caller wants to know if the specified unit has been allocated
116 * or not. Return 0, indicating that it has not been allocated.
118 * Caller must hold a lock to prevent chk-to-set races.
120 * (the bitmap implements 0=allocated, 1=not-allocated but the
121 * return value is inverted).
124 devfs_clone_bitmap_chk(struct devfs_bitmap *bitmap, int unit)
128 chunk = unit / (sizeof(u_long) * 8);
129 unit -= chunk * (sizeof(u_long) * 8);
131 if (chunk >= bitmap->chunks)
132 return 0; /* device does not exist */
134 return !((bitmap->bitmap[chunk]) & (1L << unit));
138 * Unconditionally mark the specified unit as allocated in the bitmap.
140 * Caller must hold a lock to prevent chk-to-set races. If the unit had
141 * never been allocated in the past, a token lock might not be sufficient
142 * to avoid races (if this function must extend the bitmap it could block
143 * temporary in kmalloc()).
146 devfs_clone_bitmap_set(struct devfs_bitmap *bitmap, int unit)
150 chunk = unit / (sizeof(u_long) * 8);
151 unit -= chunk * (sizeof(u_long) * 8);
153 if (chunk >= bitmap->chunks)
154 devfs_clone_bitmap_extend(bitmap, chunk);
155 bitmap->bitmap[chunk] &= ~(1L << unit);
159 * Unconditionally deallocate a unit number. Caller must synchronize any
160 * destroy_dev()'s the device called before clearing the bitmap bit to
161 * avoid races against a new clone.
164 devfs_clone_bitmap_put(struct devfs_bitmap *bitmap, int unit)
170 chunk = unit / (sizeof(u_long) * 8);
171 unit -= chunk * (sizeof(u_long) * 8);
173 if (chunk >= bitmap->chunks)
175 bitmap->bitmap[chunk] |= (1L << unit);
179 * Conditionally allocate a unit from the bitmap. Returns -1 if no
180 * more units are available.
182 * Caller must hold a lock to avoid bitmap races. Since *_fff() below
183 * pre-extends the bitmap as necessary, a token lock is sufficient.
186 devfs_clone_bitmap_get(struct devfs_bitmap *bitmap, int limit)
190 unit = devfs_clone_bitmap_fff(bitmap);
191 if ((limit > 0) && (unit > limit))
193 devfs_clone_bitmap_set(bitmap, unit);