Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
Stefani Seibold | 4546548 | 2009-12-21 14:37:26 -0800 | [diff] [blame] | 2 | * A generic kernel FIFO implementation. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3 | * |
Stefani Seibold | 4546548 | 2009-12-21 14:37:26 -0800 | [diff] [blame] | 4 | * Copyright (C) 2009 Stefani Seibold <stefani@seibold.net> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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> |
vignesh babu | f84d5a7 | 2007-07-15 23:41:34 -0700 | [diff] [blame] | 28 | #include <linux/log2.h> |
Stefani Seibold | a121f24 | 2009-12-21 14:37:31 -0800 | [diff] [blame^] | 29 | #include <linux/uaccess.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 30 | |
Stefani Seibold | 4546548 | 2009-12-21 14:37:26 -0800 | [diff] [blame] | 31 | static void _kfifo_init(struct kfifo *fifo, unsigned char *buffer, |
Stefani Seibold | c1e13f2 | 2009-12-21 14:37:27 -0800 | [diff] [blame] | 32 | unsigned int size) |
Stefani Seibold | 4546548 | 2009-12-21 14:37:26 -0800 | [diff] [blame] | 33 | { |
| 34 | fifo->buffer = buffer; |
| 35 | fifo->size = size; |
Stefani Seibold | 4546548 | 2009-12-21 14:37:26 -0800 | [diff] [blame] | 36 | |
| 37 | kfifo_reset(fifo); |
| 38 | } |
| 39 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 40 | /** |
Stefani Seibold | 4546548 | 2009-12-21 14:37:26 -0800 | [diff] [blame] | 41 | * kfifo_init - initialize a FIFO using a preallocated buffer |
| 42 | * @fifo: the fifo to assign the buffer |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 43 | * @buffer: the preallocated buffer to be used. |
| 44 | * @size: the size of the internal buffer, this have to be a power of 2. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 45 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 46 | */ |
Stefani Seibold | c1e13f2 | 2009-12-21 14:37:27 -0800 | [diff] [blame] | 47 | void kfifo_init(struct kfifo *fifo, unsigned char *buffer, unsigned int size) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 48 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 49 | /* size must be a power of 2 */ |
vignesh babu | f84d5a7 | 2007-07-15 23:41:34 -0700 | [diff] [blame] | 50 | BUG_ON(!is_power_of_2(size)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 51 | |
Stefani Seibold | c1e13f2 | 2009-12-21 14:37:27 -0800 | [diff] [blame] | 52 | _kfifo_init(fifo, buffer, size); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 53 | } |
| 54 | EXPORT_SYMBOL(kfifo_init); |
| 55 | |
| 56 | /** |
Stefani Seibold | 4546548 | 2009-12-21 14:37:26 -0800 | [diff] [blame] | 57 | * kfifo_alloc - allocates a new FIFO internal buffer |
| 58 | * @fifo: the fifo to assign then new buffer |
| 59 | * @size: the size of the buffer to be allocated, this have to be a power of 2. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 60 | * @gfp_mask: get_free_pages mask, passed to kmalloc() |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 61 | * |
Stefani Seibold | 4546548 | 2009-12-21 14:37:26 -0800 | [diff] [blame] | 62 | * This function dynamically allocates a new fifo internal buffer |
| 63 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 64 | * The size will be rounded-up to a power of 2. |
Stefani Seibold | 4546548 | 2009-12-21 14:37:26 -0800 | [diff] [blame] | 65 | * The buffer will be release with kfifo_free(). |
| 66 | * Return 0 if no error, otherwise the an error code |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 67 | */ |
Stefani Seibold | c1e13f2 | 2009-12-21 14:37:27 -0800 | [diff] [blame] | 68 | int kfifo_alloc(struct kfifo *fifo, unsigned int size, gfp_t gfp_mask) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 69 | { |
| 70 | unsigned char *buffer; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 71 | |
| 72 | /* |
| 73 | * round up to the next power of 2, since our 'let the indices |
Robert P. J. Day | b33112d | 2009-06-16 15:33:34 -0700 | [diff] [blame] | 74 | * wrap' technique works only in this case. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 75 | */ |
Robert P. J. Day | b33112d | 2009-06-16 15:33:34 -0700 | [diff] [blame] | 76 | if (!is_power_of_2(size)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 77 | BUG_ON(size > 0x80000000); |
| 78 | size = roundup_pow_of_two(size); |
| 79 | } |
| 80 | |
| 81 | buffer = kmalloc(size, gfp_mask); |
Stefani Seibold | 4546548 | 2009-12-21 14:37:26 -0800 | [diff] [blame] | 82 | if (!buffer) { |
Stefani Seibold | c1e13f2 | 2009-12-21 14:37:27 -0800 | [diff] [blame] | 83 | _kfifo_init(fifo, 0, 0); |
Stefani Seibold | 4546548 | 2009-12-21 14:37:26 -0800 | [diff] [blame] | 84 | return -ENOMEM; |
| 85 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 86 | |
Stefani Seibold | c1e13f2 | 2009-12-21 14:37:27 -0800 | [diff] [blame] | 87 | _kfifo_init(fifo, buffer, size); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 88 | |
Stefani Seibold | 4546548 | 2009-12-21 14:37:26 -0800 | [diff] [blame] | 89 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 90 | } |
| 91 | EXPORT_SYMBOL(kfifo_alloc); |
| 92 | |
| 93 | /** |
Stefani Seibold | 4546548 | 2009-12-21 14:37:26 -0800 | [diff] [blame] | 94 | * kfifo_free - frees the FIFO internal buffer |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 95 | * @fifo: the fifo to be freed. |
| 96 | */ |
| 97 | void kfifo_free(struct kfifo *fifo) |
| 98 | { |
| 99 | kfree(fifo->buffer); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 100 | } |
| 101 | EXPORT_SYMBOL(kfifo_free); |
| 102 | |
| 103 | /** |
Stefani Seibold | a121f24 | 2009-12-21 14:37:31 -0800 | [diff] [blame^] | 104 | * kfifo_skip - skip output data |
| 105 | * @fifo: the fifo to be used. |
| 106 | * @len: number of bytes to skip |
| 107 | */ |
| 108 | void kfifo_skip(struct kfifo *fifo, unsigned int len) |
| 109 | { |
| 110 | if (len < kfifo_len(fifo)) { |
| 111 | __kfifo_add_out(fifo, len); |
| 112 | return; |
| 113 | } |
| 114 | kfifo_reset_out(fifo); |
| 115 | } |
| 116 | EXPORT_SYMBOL(kfifo_skip); |
| 117 | |
| 118 | /** |
Stefani Seibold | 7acd72e | 2009-12-21 14:37:28 -0800 | [diff] [blame] | 119 | * kfifo_in - puts some data into the FIFO |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 120 | * @fifo: the fifo to be used. |
Stefani Seibold | 7acd72e | 2009-12-21 14:37:28 -0800 | [diff] [blame] | 121 | * @from: the data to be added. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 122 | * @len: the length of the data to be added. |
| 123 | * |
Stefani Seibold | 7acd72e | 2009-12-21 14:37:28 -0800 | [diff] [blame] | 124 | * This function copies at most @len bytes from the @from buffer into |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 125 | * the FIFO depending on the free space, and returns the number of |
| 126 | * bytes copied. |
| 127 | * |
| 128 | * Note that with only one concurrent reader and one concurrent |
| 129 | * writer, you don't need extra locking to use these functions. |
| 130 | */ |
Stefani Seibold | 7acd72e | 2009-12-21 14:37:28 -0800 | [diff] [blame] | 131 | unsigned int kfifo_in(struct kfifo *fifo, |
| 132 | const unsigned char *from, unsigned int len) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 133 | { |
Stefani Seibold | a121f24 | 2009-12-21 14:37:31 -0800 | [diff] [blame^] | 134 | unsigned int off; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 135 | unsigned int l; |
| 136 | |
| 137 | len = min(len, fifo->size - fifo->in + fifo->out); |
| 138 | |
Paul E. McKenney | a45bce4 | 2006-09-29 02:00:11 -0700 | [diff] [blame] | 139 | /* |
| 140 | * Ensure that we sample the fifo->out index -before- we |
| 141 | * start putting bytes into the kfifo. |
| 142 | */ |
| 143 | |
| 144 | smp_mb(); |
| 145 | |
Stefani Seibold | a121f24 | 2009-12-21 14:37:31 -0800 | [diff] [blame^] | 146 | off = __kfifo_off(fifo, fifo->in); |
| 147 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 148 | /* first put the data starting from fifo->in to buffer end */ |
Stefani Seibold | a121f24 | 2009-12-21 14:37:31 -0800 | [diff] [blame^] | 149 | l = min(len, fifo->size - off); |
| 150 | memcpy(fifo->buffer + off, from, l); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 151 | |
| 152 | /* then put the rest (if any) at the beginning of the buffer */ |
Stefani Seibold | 7acd72e | 2009-12-21 14:37:28 -0800 | [diff] [blame] | 153 | memcpy(fifo->buffer, from + l, len - l); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 154 | |
Stefani Seibold | a121f24 | 2009-12-21 14:37:31 -0800 | [diff] [blame^] | 155 | __kfifo_add_in(fifo, len); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 156 | |
| 157 | return len; |
| 158 | } |
Stefani Seibold | 7acd72e | 2009-12-21 14:37:28 -0800 | [diff] [blame] | 159 | EXPORT_SYMBOL(kfifo_in); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 160 | |
| 161 | /** |
Stefani Seibold | 7acd72e | 2009-12-21 14:37:28 -0800 | [diff] [blame] | 162 | * kfifo_out - gets some data from the FIFO |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 163 | * @fifo: the fifo to be used. |
Stefani Seibold | 7acd72e | 2009-12-21 14:37:28 -0800 | [diff] [blame] | 164 | * @to: where the data must be copied. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 165 | * @len: the size of the destination buffer. |
| 166 | * |
Robert P. J. Day | 72fd4a3 | 2007-02-10 01:45:59 -0800 | [diff] [blame] | 167 | * This function copies at most @len bytes from the FIFO into the |
Stefani Seibold | 7acd72e | 2009-12-21 14:37:28 -0800 | [diff] [blame] | 168 | * @to buffer and returns the number of copied bytes. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 169 | * |
| 170 | * Note that with only one concurrent reader and one concurrent |
| 171 | * writer, you don't need extra locking to use these functions. |
| 172 | */ |
Stefani Seibold | 7acd72e | 2009-12-21 14:37:28 -0800 | [diff] [blame] | 173 | unsigned int kfifo_out(struct kfifo *fifo, |
| 174 | unsigned char *to, unsigned int len) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 175 | { |
Stefani Seibold | a121f24 | 2009-12-21 14:37:31 -0800 | [diff] [blame^] | 176 | unsigned int off; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 177 | unsigned int l; |
| 178 | |
| 179 | len = min(len, fifo->in - fifo->out); |
| 180 | |
Paul E. McKenney | a45bce4 | 2006-09-29 02:00:11 -0700 | [diff] [blame] | 181 | /* |
| 182 | * Ensure that we sample the fifo->in index -before- we |
| 183 | * start removing bytes from the kfifo. |
| 184 | */ |
| 185 | |
| 186 | smp_rmb(); |
| 187 | |
Stefani Seibold | a121f24 | 2009-12-21 14:37:31 -0800 | [diff] [blame^] | 188 | off = __kfifo_off(fifo, fifo->out); |
| 189 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 190 | /* first get the data from fifo->out until the end of the buffer */ |
Stefani Seibold | a121f24 | 2009-12-21 14:37:31 -0800 | [diff] [blame^] | 191 | l = min(len, fifo->size - off); |
| 192 | memcpy(to, fifo->buffer + off, l); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 193 | |
| 194 | /* then get the rest (if any) from the beginning of the buffer */ |
Stefani Seibold | 7acd72e | 2009-12-21 14:37:28 -0800 | [diff] [blame] | 195 | memcpy(to + l, fifo->buffer, len - l); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 196 | |
Stefani Seibold | a121f24 | 2009-12-21 14:37:31 -0800 | [diff] [blame^] | 197 | __kfifo_add_out(fifo, len); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 198 | |
| 199 | return len; |
| 200 | } |
Stefani Seibold | 7acd72e | 2009-12-21 14:37:28 -0800 | [diff] [blame] | 201 | EXPORT_SYMBOL(kfifo_out); |
Stefani Seibold | a121f24 | 2009-12-21 14:37:31 -0800 | [diff] [blame^] | 202 | |
| 203 | /** |
| 204 | * kfifo_from_user - puts some data from user space into the FIFO |
| 205 | * @fifo: the fifo to be used. |
| 206 | * @from: pointer to the data to be added. |
| 207 | * @len: the length of the data to be added. |
| 208 | * |
| 209 | * This function copies at most @len bytes from the @from into the |
| 210 | * FIFO depending and returns the number of copied bytes. |
| 211 | * |
| 212 | * Note that with only one concurrent reader and one concurrent |
| 213 | * writer, you don't need extra locking to use these functions. |
| 214 | */ |
| 215 | unsigned int kfifo_from_user(struct kfifo *fifo, |
| 216 | const void __user *from, unsigned int len) |
| 217 | { |
| 218 | unsigned int off; |
| 219 | unsigned int l; |
| 220 | int ret; |
| 221 | |
| 222 | len = min(len, fifo->size - fifo->in + fifo->out); |
| 223 | |
| 224 | /* |
| 225 | * Ensure that we sample the fifo->out index -before- we |
| 226 | * start putting bytes into the kfifo. |
| 227 | */ |
| 228 | |
| 229 | smp_mb(); |
| 230 | |
| 231 | off = __kfifo_off(fifo, fifo->in); |
| 232 | |
| 233 | /* first put the data starting from fifo->in to buffer end */ |
| 234 | l = min(len, fifo->size - off); |
| 235 | ret = copy_from_user(fifo->buffer + off, from, l); |
| 236 | |
| 237 | if (unlikely(ret)) |
| 238 | return l - ret; |
| 239 | |
| 240 | /* then put the rest (if any) at the beginning of the buffer */ |
| 241 | ret = copy_from_user(fifo->buffer, from + l, len - l); |
| 242 | |
| 243 | if (unlikely(ret)) |
| 244 | return len - ret; |
| 245 | |
| 246 | __kfifo_add_in(fifo, len); |
| 247 | |
| 248 | return len; |
| 249 | } |
| 250 | EXPORT_SYMBOL(kfifo_from_user); |
| 251 | |
| 252 | /** |
| 253 | * kfifo_to_user - gets data from the FIFO and write it to user space |
| 254 | * @fifo: the fifo to be used. |
| 255 | * @to: where the data must be copied. |
| 256 | * @len: the size of the destination buffer. |
| 257 | * |
| 258 | * This function copies at most @len bytes from the FIFO into the |
| 259 | * @to buffer and returns the number of copied bytes. |
| 260 | * |
| 261 | * Note that with only one concurrent reader and one concurrent |
| 262 | * writer, you don't need extra locking to use these functions. |
| 263 | */ |
| 264 | unsigned int kfifo_to_user(struct kfifo *fifo, |
| 265 | void __user *to, unsigned int len) |
| 266 | { |
| 267 | unsigned int off; |
| 268 | unsigned int l; |
| 269 | int ret; |
| 270 | |
| 271 | len = min(len, fifo->in - fifo->out); |
| 272 | |
| 273 | /* |
| 274 | * Ensure that we sample the fifo->in index -before- we |
| 275 | * start removing bytes from the kfifo. |
| 276 | */ |
| 277 | |
| 278 | smp_rmb(); |
| 279 | |
| 280 | off = __kfifo_off(fifo, fifo->out); |
| 281 | |
| 282 | /* first get the data from fifo->out until the end of the buffer */ |
| 283 | l = min(len, fifo->size - off); |
| 284 | ret = copy_to_user(to, fifo->buffer + off, l); |
| 285 | |
| 286 | if (unlikely(ret)) |
| 287 | return l - ret; |
| 288 | |
| 289 | /* then get the rest (if any) from the beginning of the buffer */ |
| 290 | ret = copy_to_user(to + l, fifo->buffer, len - l); |
| 291 | |
| 292 | if (unlikely(ret)) |
| 293 | return len - ret; |
| 294 | |
| 295 | __kfifo_add_out(fifo, len); |
| 296 | |
| 297 | return len; |
| 298 | } |
| 299 | EXPORT_SYMBOL(kfifo_to_user); |
| 300 | |