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
|
#include "kerncompat.h"
#include "radix-tree.h"
#define BIT_ARRAY_BYTES 256
#define BIT_RADIX_BITS_PER_ARRAY ((BIT_ARRAY_BYTES - sizeof(unsigned long)) * 8)
int set_radix_bit(struct radix_tree_root *radix, unsigned long bit)
{
unsigned long *bits;
unsigned long slot;
int bit_slot;
int ret;
slot = bit / BIT_RADIX_BITS_PER_ARRAY;
bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;
bits = radix_tree_lookup(radix, slot);
if (!bits) {
bits = malloc(BIT_ARRAY_BYTES);
if (!bits)
return -ENOMEM;
memset(bits + 1, 0, BIT_ARRAY_BYTES - sizeof(unsigned long));
bits[0] = slot;
radix_tree_preload(GFP_NOFS);
ret = radix_tree_insert(radix, slot, bits);
radix_tree_preload_end();
if (ret)
return ret;
}
__set_bit(bit_slot, bits + 1);
return 0;
}
int test_radix_bit(struct radix_tree_root *radix, unsigned long bit)
{
unsigned long *bits;
unsigned long slot;
int bit_slot;
slot = bit / BIT_RADIX_BITS_PER_ARRAY;
bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;
bits = radix_tree_lookup(radix, slot);
if (!bits)
return 0;
return test_bit(bit_slot, bits + 1);
}
int clear_radix_bit(struct radix_tree_root *radix, unsigned long bit)
{
unsigned long *bits;
unsigned long slot;
int bit_slot;
int i;
int empty = 1;
slot = bit / BIT_RADIX_BITS_PER_ARRAY;
bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;
bits = radix_tree_lookup(radix, slot);
if (!bits)
return 0;
__clear_bit(bit_slot, bits + 1);
for (i = 1; i < BIT_ARRAY_BYTES / sizeof(unsigned long); i++) {
if (bits[i]) {
empty = 0;
break;
}
}
if (empty) {
bits = radix_tree_delete(radix, slot);
BUG_ON(!bits);
free(bits);
}
return 0;
}
#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
/**
* __ffs - find first bit in word.
* @word: The word to search
*
* Undefined if no bit exists, so code should check against 0 first.
*/
static unsigned long __ffs(unsigned long word)
{
int num = 0;
#if BITS_PER_LONG == 64
if ((word & 0xffffffff) == 0) {
num += 32;
word >>= 32;
}
#endif
if ((word & 0xffff) == 0) {
num += 16;
word >>= 16;
}
if ((word & 0xff) == 0) {
num += 8;
word >>= 8;
}
if ((word & 0xf) == 0) {
num += 4;
word >>= 4;
}
if ((word & 0x3) == 0) {
num += 2;
word >>= 2;
}
if ((word & 0x1) == 0)
num += 1;
return num;
}
/**
* find_next_bit - find the next set bit in a memory region
* @addr: The address to base the search on
* @offset: The bitnumber to start searching at
* @size: The maximum size to search
*/
unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
unsigned long offset)
{
const unsigned long *p = addr + BITOP_WORD(offset);
unsigned long result = offset & ~(BITS_PER_LONG-1);
unsigned long tmp;
if (offset >= size)
return size;
size -= result;
offset %= BITS_PER_LONG;
if (offset) {
tmp = *(p++);
tmp &= (~0UL << offset);
if (size < BITS_PER_LONG)
goto found_first;
if (tmp)
goto found_middle;
size -= BITS_PER_LONG;
result += BITS_PER_LONG;
}
while (size & ~(BITS_PER_LONG-1)) {
if ((tmp = *(p++)))
goto found_middle;
result += BITS_PER_LONG;
size -= BITS_PER_LONG;
}
if (!size)
return result;
tmp = *p;
found_first:
tmp &= (~0UL >> (BITS_PER_LONG - size));
if (tmp == 0UL) /* Are any bits set? */
return result + size; /* Nope. */
found_middle:
return result + __ffs(tmp);
}
int find_first_radix_bit(struct radix_tree_root *radix, unsigned long *retbits,
unsigned long start, int nr)
{
unsigned long *bits;
unsigned long *gang[4];
int found;
int ret;
int i;
int total_found = 0;
unsigned long slot;
slot = start / BIT_RADIX_BITS_PER_ARRAY;
ret = radix_tree_gang_lookup(radix, (void **)gang, slot,
ARRAY_SIZE(gang));
found = start % BIT_RADIX_BITS_PER_ARRAY;
for (i = 0; i < ret && nr > 0; i++) {
bits = gang[i];
while(nr > 0) {
found = find_next_bit(bits + 1,
BIT_RADIX_BITS_PER_ARRAY,
found);
if (found < BIT_RADIX_BITS_PER_ARRAY) {
*retbits = bits[0] *
BIT_RADIX_BITS_PER_ARRAY + found;
retbits++;
nr--;
total_found++;
found++;
} else
break;
}
found = 0;
}
return total_found;
}
|
