Commit | Line | Data |
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1da177e4 | 1 | /* |
45465487 | 2 | * A generic kernel FIFO implementation. |
1da177e4 | 3 | * |
45465487 | 4 | * Copyright (C) 2009 Stefani Seibold <stefani@seibold.net> |
1da177e4 LT |
5 | * Copyright (C) 2004 Stelian Pop <stelian@popies.net> |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License as published by | |
9 | * the Free Software Foundation; either version 2 of the License, or | |
10 | * (at your option) any later version. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | * GNU General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public License | |
18 | * along with this program; if not, write to the Free Software | |
19 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
20 | * | |
21 | */ | |
22 | ||
23 | #include <linux/kernel.h> | |
24 | #include <linux/module.h> | |
25 | #include <linux/slab.h> | |
26 | #include <linux/err.h> | |
27 | #include <linux/kfifo.h> | |
f84d5a76 | 28 | #include <linux/log2.h> |
1da177e4 | 29 | |
45465487 | 30 | static void _kfifo_init(struct kfifo *fifo, unsigned char *buffer, |
c1e13f25 | 31 | unsigned int size) |
45465487 SS |
32 | { |
33 | fifo->buffer = buffer; | |
34 | fifo->size = size; | |
45465487 SS |
35 | |
36 | kfifo_reset(fifo); | |
37 | } | |
38 | ||
1da177e4 | 39 | /** |
45465487 SS |
40 | * kfifo_init - initialize a FIFO using a preallocated buffer |
41 | * @fifo: the fifo to assign the buffer | |
1da177e4 LT |
42 | * @buffer: the preallocated buffer to be used. |
43 | * @size: the size of the internal buffer, this have to be a power of 2. | |
1da177e4 | 44 | * |
1da177e4 | 45 | */ |
c1e13f25 | 46 | void kfifo_init(struct kfifo *fifo, unsigned char *buffer, unsigned int size) |
1da177e4 | 47 | { |
1da177e4 | 48 | /* size must be a power of 2 */ |
f84d5a76 | 49 | BUG_ON(!is_power_of_2(size)); |
1da177e4 | 50 | |
c1e13f25 | 51 | _kfifo_init(fifo, buffer, size); |
1da177e4 LT |
52 | } |
53 | EXPORT_SYMBOL(kfifo_init); | |
54 | ||
55 | /** | |
45465487 SS |
56 | * kfifo_alloc - allocates a new FIFO internal buffer |
57 | * @fifo: the fifo to assign then new buffer | |
58 | * @size: the size of the buffer to be allocated, this have to be a power of 2. | |
1da177e4 | 59 | * @gfp_mask: get_free_pages mask, passed to kmalloc() |
1da177e4 | 60 | * |
45465487 SS |
61 | * This function dynamically allocates a new fifo internal buffer |
62 | * | |
1da177e4 | 63 | * The size will be rounded-up to a power of 2. |
45465487 SS |
64 | * The buffer will be release with kfifo_free(). |
65 | * Return 0 if no error, otherwise the an error code | |
1da177e4 | 66 | */ |
c1e13f25 | 67 | int kfifo_alloc(struct kfifo *fifo, unsigned int size, gfp_t gfp_mask) |
1da177e4 LT |
68 | { |
69 | unsigned char *buffer; | |
1da177e4 LT |
70 | |
71 | /* | |
72 | * round up to the next power of 2, since our 'let the indices | |
b33112d1 | 73 | * wrap' technique works only in this case. |
1da177e4 | 74 | */ |
b33112d1 | 75 | if (!is_power_of_2(size)) { |
1da177e4 LT |
76 | BUG_ON(size > 0x80000000); |
77 | size = roundup_pow_of_two(size); | |
78 | } | |
79 | ||
80 | buffer = kmalloc(size, gfp_mask); | |
45465487 | 81 | if (!buffer) { |
c1e13f25 | 82 | _kfifo_init(fifo, 0, 0); |
45465487 SS |
83 | return -ENOMEM; |
84 | } | |
1da177e4 | 85 | |
c1e13f25 | 86 | _kfifo_init(fifo, buffer, size); |
1da177e4 | 87 | |
45465487 | 88 | return 0; |
1da177e4 LT |
89 | } |
90 | EXPORT_SYMBOL(kfifo_alloc); | |
91 | ||
92 | /** | |
45465487 | 93 | * kfifo_free - frees the FIFO internal buffer |
1da177e4 LT |
94 | * @fifo: the fifo to be freed. |
95 | */ | |
96 | void kfifo_free(struct kfifo *fifo) | |
97 | { | |
98 | kfree(fifo->buffer); | |
1da177e4 LT |
99 | } |
100 | EXPORT_SYMBOL(kfifo_free); | |
101 | ||
102 | /** | |
e64c026d | 103 | * kfifo_put - puts some data into the FIFO, no locking version |
1da177e4 LT |
104 | * @fifo: the fifo to be used. |
105 | * @buffer: the data to be added. | |
106 | * @len: the length of the data to be added. | |
107 | * | |
72fd4a35 | 108 | * This function copies at most @len bytes from the @buffer into |
1da177e4 LT |
109 | * the FIFO depending on the free space, and returns the number of |
110 | * bytes copied. | |
111 | * | |
112 | * Note that with only one concurrent reader and one concurrent | |
113 | * writer, you don't need extra locking to use these functions. | |
114 | */ | |
e64c026d | 115 | unsigned int kfifo_put(struct kfifo *fifo, |
f8a7c1a9 | 116 | const unsigned char *buffer, unsigned int len) |
1da177e4 LT |
117 | { |
118 | unsigned int l; | |
119 | ||
120 | len = min(len, fifo->size - fifo->in + fifo->out); | |
121 | ||
a45bce49 PM |
122 | /* |
123 | * Ensure that we sample the fifo->out index -before- we | |
124 | * start putting bytes into the kfifo. | |
125 | */ | |
126 | ||
127 | smp_mb(); | |
128 | ||
1da177e4 LT |
129 | /* first put the data starting from fifo->in to buffer end */ |
130 | l = min(len, fifo->size - (fifo->in & (fifo->size - 1))); | |
131 | memcpy(fifo->buffer + (fifo->in & (fifo->size - 1)), buffer, l); | |
132 | ||
133 | /* then put the rest (if any) at the beginning of the buffer */ | |
134 | memcpy(fifo->buffer, buffer + l, len - l); | |
135 | ||
a45bce49 PM |
136 | /* |
137 | * Ensure that we add the bytes to the kfifo -before- | |
138 | * we update the fifo->in index. | |
139 | */ | |
140 | ||
141 | smp_wmb(); | |
142 | ||
1da177e4 LT |
143 | fifo->in += len; |
144 | ||
145 | return len; | |
146 | } | |
e64c026d | 147 | EXPORT_SYMBOL(kfifo_put); |
1da177e4 LT |
148 | |
149 | /** | |
e64c026d | 150 | * kfifo_get - gets some data from the FIFO, no locking version |
1da177e4 LT |
151 | * @fifo: the fifo to be used. |
152 | * @buffer: where the data must be copied. | |
153 | * @len: the size of the destination buffer. | |
154 | * | |
72fd4a35 RD |
155 | * This function copies at most @len bytes from the FIFO into the |
156 | * @buffer and returns the number of copied bytes. | |
1da177e4 LT |
157 | * |
158 | * Note that with only one concurrent reader and one concurrent | |
159 | * writer, you don't need extra locking to use these functions. | |
160 | */ | |
e64c026d | 161 | unsigned int kfifo_get(struct kfifo *fifo, |
1da177e4 LT |
162 | unsigned char *buffer, unsigned int len) |
163 | { | |
164 | unsigned int l; | |
165 | ||
166 | len = min(len, fifo->in - fifo->out); | |
167 | ||
a45bce49 PM |
168 | /* |
169 | * Ensure that we sample the fifo->in index -before- we | |
170 | * start removing bytes from the kfifo. | |
171 | */ | |
172 | ||
173 | smp_rmb(); | |
174 | ||
1da177e4 LT |
175 | /* first get the data from fifo->out until the end of the buffer */ |
176 | l = min(len, fifo->size - (fifo->out & (fifo->size - 1))); | |
177 | memcpy(buffer, fifo->buffer + (fifo->out & (fifo->size - 1)), l); | |
178 | ||
179 | /* then get the rest (if any) from the beginning of the buffer */ | |
180 | memcpy(buffer + l, fifo->buffer, len - l); | |
181 | ||
a45bce49 PM |
182 | /* |
183 | * Ensure that we remove the bytes from the kfifo -before- | |
184 | * we update the fifo->out index. | |
185 | */ | |
186 | ||
187 | smp_mb(); | |
188 | ||
1da177e4 LT |
189 | fifo->out += len; |
190 | ||
191 | return len; | |
192 | } | |
e64c026d | 193 | EXPORT_SYMBOL(kfifo_get); |