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 SS |
30 | static void _kfifo_init(struct kfifo *fifo, unsigned char *buffer, |
31 | unsigned int size, spinlock_t *lock) | |
32 | { | |
33 | fifo->buffer = buffer; | |
34 | fifo->size = size; | |
35 | fifo->lock = lock; | |
36 | ||
37 | kfifo_reset(fifo); | |
38 | } | |
39 | ||
1da177e4 | 40 | /** |
45465487 SS |
41 | * kfifo_init - initialize a FIFO using a preallocated buffer |
42 | * @fifo: the fifo to assign the buffer | |
1da177e4 LT |
43 | * @buffer: the preallocated buffer to be used. |
44 | * @size: the size of the internal buffer, this have to be a power of 2. | |
1da177e4 LT |
45 | * @lock: the lock to be used to protect the fifo buffer |
46 | * | |
1da177e4 | 47 | */ |
45465487 SS |
48 | void kfifo_init(struct kfifo *fifo, unsigned char *buffer, unsigned int size, |
49 | spinlock_t *lock) | |
1da177e4 | 50 | { |
1da177e4 | 51 | /* size must be a power of 2 */ |
f84d5a76 | 52 | BUG_ON(!is_power_of_2(size)); |
1da177e4 | 53 | |
45465487 | 54 | _kfifo_init(fifo, buffer, size, lock); |
1da177e4 LT |
55 | } |
56 | EXPORT_SYMBOL(kfifo_init); | |
57 | ||
58 | /** | |
45465487 SS |
59 | * kfifo_alloc - allocates a new FIFO internal buffer |
60 | * @fifo: the fifo to assign then new buffer | |
61 | * @size: the size of the buffer to be allocated, this have to be a power of 2. | |
1da177e4 LT |
62 | * @gfp_mask: get_free_pages mask, passed to kmalloc() |
63 | * @lock: the lock to be used to protect the fifo buffer | |
64 | * | |
45465487 SS |
65 | * This function dynamically allocates a new fifo internal buffer |
66 | * | |
1da177e4 | 67 | * The size will be rounded-up to a power of 2. |
45465487 SS |
68 | * The buffer will be release with kfifo_free(). |
69 | * Return 0 if no error, otherwise the an error code | |
1da177e4 | 70 | */ |
45465487 SS |
71 | int kfifo_alloc(struct kfifo *fifo, unsigned int size, gfp_t gfp_mask, |
72 | spinlock_t *lock) | |
1da177e4 LT |
73 | { |
74 | unsigned char *buffer; | |
1da177e4 LT |
75 | |
76 | /* | |
77 | * round up to the next power of 2, since our 'let the indices | |
b33112d1 | 78 | * wrap' technique works only in this case. |
1da177e4 | 79 | */ |
b33112d1 | 80 | if (!is_power_of_2(size)) { |
1da177e4 LT |
81 | BUG_ON(size > 0x80000000); |
82 | size = roundup_pow_of_two(size); | |
83 | } | |
84 | ||
85 | buffer = kmalloc(size, gfp_mask); | |
45465487 SS |
86 | if (!buffer) { |
87 | _kfifo_init(fifo, 0, 0, NULL); | |
88 | return -ENOMEM; | |
89 | } | |
1da177e4 | 90 | |
45465487 | 91 | _kfifo_init(fifo, buffer, size, lock); |
1da177e4 | 92 | |
45465487 | 93 | return 0; |
1da177e4 LT |
94 | } |
95 | EXPORT_SYMBOL(kfifo_alloc); | |
96 | ||
97 | /** | |
45465487 | 98 | * kfifo_free - frees the FIFO internal buffer |
1da177e4 LT |
99 | * @fifo: the fifo to be freed. |
100 | */ | |
101 | void kfifo_free(struct kfifo *fifo) | |
102 | { | |
103 | kfree(fifo->buffer); | |
1da177e4 LT |
104 | } |
105 | EXPORT_SYMBOL(kfifo_free); | |
106 | ||
107 | /** | |
108 | * __kfifo_put - puts some data into the FIFO, no locking version | |
109 | * @fifo: the fifo to be used. | |
110 | * @buffer: the data to be added. | |
111 | * @len: the length of the data to be added. | |
112 | * | |
72fd4a35 | 113 | * This function copies at most @len bytes from the @buffer into |
1da177e4 LT |
114 | * the FIFO depending on the free space, and returns the number of |
115 | * bytes copied. | |
116 | * | |
117 | * Note that with only one concurrent reader and one concurrent | |
118 | * writer, you don't need extra locking to use these functions. | |
119 | */ | |
120 | unsigned int __kfifo_put(struct kfifo *fifo, | |
f8a7c1a9 | 121 | const unsigned char *buffer, unsigned int len) |
1da177e4 LT |
122 | { |
123 | unsigned int l; | |
124 | ||
125 | len = min(len, fifo->size - fifo->in + fifo->out); | |
126 | ||
a45bce49 PM |
127 | /* |
128 | * Ensure that we sample the fifo->out index -before- we | |
129 | * start putting bytes into the kfifo. | |
130 | */ | |
131 | ||
132 | smp_mb(); | |
133 | ||
1da177e4 LT |
134 | /* first put the data starting from fifo->in to buffer end */ |
135 | l = min(len, fifo->size - (fifo->in & (fifo->size - 1))); | |
136 | memcpy(fifo->buffer + (fifo->in & (fifo->size - 1)), buffer, l); | |
137 | ||
138 | /* then put the rest (if any) at the beginning of the buffer */ | |
139 | memcpy(fifo->buffer, buffer + l, len - l); | |
140 | ||
a45bce49 PM |
141 | /* |
142 | * Ensure that we add the bytes to the kfifo -before- | |
143 | * we update the fifo->in index. | |
144 | */ | |
145 | ||
146 | smp_wmb(); | |
147 | ||
1da177e4 LT |
148 | fifo->in += len; |
149 | ||
150 | return len; | |
151 | } | |
152 | EXPORT_SYMBOL(__kfifo_put); | |
153 | ||
154 | /** | |
155 | * __kfifo_get - gets some data from the FIFO, no locking version | |
156 | * @fifo: the fifo to be used. | |
157 | * @buffer: where the data must be copied. | |
158 | * @len: the size of the destination buffer. | |
159 | * | |
72fd4a35 RD |
160 | * This function copies at most @len bytes from the FIFO into the |
161 | * @buffer and returns the number of copied bytes. | |
1da177e4 LT |
162 | * |
163 | * Note that with only one concurrent reader and one concurrent | |
164 | * writer, you don't need extra locking to use these functions. | |
165 | */ | |
166 | unsigned int __kfifo_get(struct kfifo *fifo, | |
167 | unsigned char *buffer, unsigned int len) | |
168 | { | |
169 | unsigned int l; | |
170 | ||
171 | len = min(len, fifo->in - fifo->out); | |
172 | ||
a45bce49 PM |
173 | /* |
174 | * Ensure that we sample the fifo->in index -before- we | |
175 | * start removing bytes from the kfifo. | |
176 | */ | |
177 | ||
178 | smp_rmb(); | |
179 | ||
1da177e4 LT |
180 | /* first get the data from fifo->out until the end of the buffer */ |
181 | l = min(len, fifo->size - (fifo->out & (fifo->size - 1))); | |
182 | memcpy(buffer, fifo->buffer + (fifo->out & (fifo->size - 1)), l); | |
183 | ||
184 | /* then get the rest (if any) from the beginning of the buffer */ | |
185 | memcpy(buffer + l, fifo->buffer, len - l); | |
186 | ||
a45bce49 PM |
187 | /* |
188 | * Ensure that we remove the bytes from the kfifo -before- | |
189 | * we update the fifo->out index. | |
190 | */ | |
191 | ||
192 | smp_mb(); | |
193 | ||
1da177e4 LT |
194 | fifo->out += len; |
195 | ||
196 | return len; | |
197 | } | |
198 | EXPORT_SYMBOL(__kfifo_get); |