Blame view
kernel/kfifo.c
5.1 KB
1da177e4c Linux-2.6.12-rc2 |
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 |
/* * A simple kernel FIFO implementation. * * Copyright (C) 2004 Stelian Pop <stelian@popies.net> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/slab.h> #include <linux/err.h> #include <linux/kfifo.h> |
f84d5a76c is_power_of_2: ke... |
27 |
#include <linux/log2.h> |
1da177e4c Linux-2.6.12-rc2 |
28 29 30 31 32 33 34 35 |
/** * kfifo_init - allocates a new FIFO using a preallocated buffer * @buffer: the preallocated buffer to be used. * @size: the size of the internal buffer, this have to be a power of 2. * @gfp_mask: get_free_pages mask, passed to kmalloc() * @lock: the lock to be used to protect the fifo buffer * |
72fd4a35a [PATCH] Numerous ... |
36 37 |
* Do NOT pass the kfifo to kfifo_free() after use! Simply free the * &struct kfifo with kfree(). |
1da177e4c Linux-2.6.12-rc2 |
38 39 |
*/ struct kfifo *kfifo_init(unsigned char *buffer, unsigned int size, |
dd0fc66fb [PATCH] gfp flags... |
40 |
gfp_t gfp_mask, spinlock_t *lock) |
1da177e4c Linux-2.6.12-rc2 |
41 42 43 44 |
{ struct kfifo *fifo; /* size must be a power of 2 */ |
f84d5a76c is_power_of_2: ke... |
45 |
BUG_ON(!is_power_of_2(size)); |
1da177e4c Linux-2.6.12-rc2 |
46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 |
fifo = kmalloc(sizeof(struct kfifo), gfp_mask); if (!fifo) return ERR_PTR(-ENOMEM); fifo->buffer = buffer; fifo->size = size; fifo->in = fifo->out = 0; fifo->lock = lock; return fifo; } EXPORT_SYMBOL(kfifo_init); /** * kfifo_alloc - allocates a new FIFO and its internal buffer * @size: the size of the internal buffer to be allocated. * @gfp_mask: get_free_pages mask, passed to kmalloc() * @lock: the lock to be used to protect the fifo buffer * * The size will be rounded-up to a power of 2. */ |
dd0fc66fb [PATCH] gfp flags... |
68 |
struct kfifo *kfifo_alloc(unsigned int size, gfp_t gfp_mask, spinlock_t *lock) |
1da177e4c Linux-2.6.12-rc2 |
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 |
{ unsigned char *buffer; struct kfifo *ret; /* * round up to the next power of 2, since our 'let the indices * wrap' tachnique works only in this case. */ if (size & (size - 1)) { BUG_ON(size > 0x80000000); size = roundup_pow_of_two(size); } buffer = kmalloc(size, gfp_mask); if (!buffer) return ERR_PTR(-ENOMEM); ret = kfifo_init(buffer, size, gfp_mask, lock); if (IS_ERR(ret)) kfree(buffer); return ret; } EXPORT_SYMBOL(kfifo_alloc); /** * kfifo_free - frees the FIFO * @fifo: the fifo to be freed. */ void kfifo_free(struct kfifo *fifo) { kfree(fifo->buffer); kfree(fifo); } EXPORT_SYMBOL(kfifo_free); /** * __kfifo_put - puts some data into the FIFO, no locking version * @fifo: the fifo to be used. * @buffer: the data to be added. * @len: the length of the data to be added. * |
72fd4a35a [PATCH] Numerous ... |
112 |
* This function copies at most @len bytes from the @buffer into |
1da177e4c Linux-2.6.12-rc2 |
113 114 115 116 117 118 119 120 121 122 123 124 |
* the FIFO depending on the free space, and returns the number of * bytes copied. * * Note that with only one concurrent reader and one concurrent * writer, you don't need extra locking to use these functions. */ unsigned int __kfifo_put(struct kfifo *fifo, unsigned char *buffer, unsigned int len) { unsigned int l; len = min(len, fifo->size - fifo->in + fifo->out); |
a45bce495 [PATCH] memory or... |
125 126 127 128 129 130 |
/* * Ensure that we sample the fifo->out index -before- we * start putting bytes into the kfifo. */ smp_mb(); |
1da177e4c Linux-2.6.12-rc2 |
131 132 133 134 135 136 |
/* first put the data starting from fifo->in to buffer end */ l = min(len, fifo->size - (fifo->in & (fifo->size - 1))); memcpy(fifo->buffer + (fifo->in & (fifo->size - 1)), buffer, l); /* then put the rest (if any) at the beginning of the buffer */ memcpy(fifo->buffer, buffer + l, len - l); |
a45bce495 [PATCH] memory or... |
137 138 139 140 141 142 |
/* * Ensure that we add the bytes to the kfifo -before- * we update the fifo->in index. */ smp_wmb(); |
1da177e4c Linux-2.6.12-rc2 |
143 144 145 146 147 148 149 150 151 152 153 154 |
fifo->in += len; return len; } EXPORT_SYMBOL(__kfifo_put); /** * __kfifo_get - gets some data from the FIFO, no locking version * @fifo: the fifo to be used. * @buffer: where the data must be copied. * @len: the size of the destination buffer. * |
72fd4a35a [PATCH] Numerous ... |
155 156 |
* This function copies at most @len bytes from the FIFO into the * @buffer and returns the number of copied bytes. |
1da177e4c Linux-2.6.12-rc2 |
157 158 159 160 161 162 163 164 165 166 |
* * Note that with only one concurrent reader and one concurrent * writer, you don't need extra locking to use these functions. */ unsigned int __kfifo_get(struct kfifo *fifo, unsigned char *buffer, unsigned int len) { unsigned int l; len = min(len, fifo->in - fifo->out); |
a45bce495 [PATCH] memory or... |
167 168 169 170 171 172 |
/* * Ensure that we sample the fifo->in index -before- we * start removing bytes from the kfifo. */ smp_rmb(); |
1da177e4c Linux-2.6.12-rc2 |
173 174 175 176 177 178 |
/* first get the data from fifo->out until the end of the buffer */ l = min(len, fifo->size - (fifo->out & (fifo->size - 1))); memcpy(buffer, fifo->buffer + (fifo->out & (fifo->size - 1)), l); /* then get the rest (if any) from the beginning of the buffer */ memcpy(buffer + l, fifo->buffer, len - l); |
a45bce495 [PATCH] memory or... |
179 180 181 182 183 184 |
/* * Ensure that we remove the bytes from the kfifo -before- * we update the fifo->out index. */ smp_mb(); |
1da177e4c Linux-2.6.12-rc2 |
185 186 187 188 189 |
fifo->out += len; return len; } EXPORT_SYMBOL(__kfifo_get); |