diff options
author | Stefani Seibold <stefani@seibold.net> | 2010-08-10 21:03:39 -0400 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-08-11 11:59:23 -0400 |
commit | 5bf2b19320ec31d094d7370fdf536f7fd91fd799 (patch) | |
tree | 47052fd9bdb0969d4a4a7d430695388094409964 /samples/kfifo/record-example.c | |
parent | 2e956fb320568cc70861761483e2f0e2db75fd66 (diff) |
kfifo: add example files to the kernel sample directory
Add four examples to the kernel sample directory.
It shows how to handle:
- a byte stream fifo
- a integer type fifo
- a dynamic record sized fifo
- the fifo DMA functions
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'samples/kfifo/record-example.c')
-rw-r--r-- | samples/kfifo/record-example.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/samples/kfifo/record-example.c b/samples/kfifo/record-example.c new file mode 100644 index 00000000000..32c6e0bda74 --- /dev/null +++ b/samples/kfifo/record-example.c | |||
@@ -0,0 +1,167 @@ | |||
1 | /* | ||
2 | * Sample dynamic sized record fifo implementation | ||
3 | * | ||
4 | * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net> | ||
5 | * | ||
6 | * Released under the GPL version 2 only. | ||
7 | * | ||
8 | */ | ||
9 | |||
10 | #include <linux/init.h> | ||
11 | #include <linux/module.h> | ||
12 | #include <linux/proc_fs.h> | ||
13 | #include <linux/mutex.h> | ||
14 | #include <linux/kfifo.h> | ||
15 | |||
16 | /* | ||
17 | * This module shows how to create a variable sized record fifo. | ||
18 | */ | ||
19 | |||
20 | /* fifo size in elements (bytes) */ | ||
21 | #define FIFO_SIZE 128 | ||
22 | |||
23 | /* name of the proc entry */ | ||
24 | #define PROC_FIFO "record-fifo" | ||
25 | |||
26 | /* lock for procfs read access */ | ||
27 | static DEFINE_MUTEX(read_lock); | ||
28 | |||
29 | /* lock for procfs write access */ | ||
30 | static DEFINE_MUTEX(write_lock); | ||
31 | |||
32 | /* | ||
33 | * define DYNAMIC in this example for a dynamically allocated fifo. | ||
34 | * | ||
35 | * Otherwise the fifo storage will be a part of the fifo structure. | ||
36 | */ | ||
37 | #if 0 | ||
38 | #define DYNAMIC | ||
39 | #endif | ||
40 | |||
41 | /* | ||
42 | * struct kfifo_rec_ptr_1 and STRUCT_KFIFO_REC_1 can handle records of a | ||
43 | * length between 0 and 255 bytes. | ||
44 | * | ||
45 | * struct kfifo_rec_ptr_2 and STRUCT_KFIFO_REC_2 can handle records of a | ||
46 | * length between 0 and 65535 bytes. | ||
47 | */ | ||
48 | |||
49 | #ifdef DYNAMIC | ||
50 | struct kfifo_rec_ptr_1 test; | ||
51 | |||
52 | #else | ||
53 | typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest; | ||
54 | |||
55 | static mytest test; | ||
56 | #endif | ||
57 | |||
58 | static int __init testfunc(void) | ||
59 | { | ||
60 | char buf[100]; | ||
61 | unsigned int i; | ||
62 | unsigned int ret; | ||
63 | struct { unsigned char buf[6]; } hello = { "hello" }; | ||
64 | |||
65 | printk(KERN_INFO "record fifo test start\n"); | ||
66 | |||
67 | kfifo_in(&test, &hello, sizeof(hello)); | ||
68 | |||
69 | /* show the size of the next record in the fifo */ | ||
70 | printk(KERN_INFO "fifo peek len: %u\n", kfifo_peek_len(&test)); | ||
71 | |||
72 | /* put in variable length data */ | ||
73 | for (i = 0; i < 10; i++) { | ||
74 | memset(buf, 'a' + i, i + 1); | ||
75 | kfifo_in(&test, buf, i + 1); | ||
76 | } | ||
77 | |||
78 | printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test)); | ||
79 | |||
80 | /* show the first record without removing from the fifo */ | ||
81 | ret = kfifo_out_peek(&test, buf, sizeof(buf)); | ||
82 | if (ret) | ||
83 | printk(KERN_INFO "%.*s\n", ret, buf); | ||
84 | |||
85 | /* print out all records in the fifo */ | ||
86 | while (!kfifo_is_empty(&test)) { | ||
87 | ret = kfifo_out(&test, buf, sizeof(buf)); | ||
88 | printk(KERN_INFO "%.*s\n", ret, buf); | ||
89 | } | ||
90 | |||
91 | return 0; | ||
92 | } | ||
93 | |||
94 | static ssize_t fifo_write(struct file *file, const char __user *buf, | ||
95 | size_t count, loff_t *ppos) | ||
96 | { | ||
97 | int ret; | ||
98 | unsigned int copied; | ||
99 | |||
100 | if (mutex_lock_interruptible(&write_lock)) | ||
101 | return -ERESTARTSYS; | ||
102 | |||
103 | ret = kfifo_from_user(&test, buf, count, &copied); | ||
104 | |||
105 | mutex_unlock(&write_lock); | ||
106 | |||
107 | return ret ? ret : copied; | ||
108 | } | ||
109 | |||
110 | static ssize_t fifo_read(struct file *file, char __user *buf, | ||
111 | size_t count, loff_t *ppos) | ||
112 | { | ||
113 | int ret; | ||
114 | unsigned int copied; | ||
115 | |||
116 | if (mutex_lock_interruptible(&read_lock)) | ||
117 | return -ERESTARTSYS; | ||
118 | |||
119 | ret = kfifo_to_user(&test, buf, count, &copied); | ||
120 | |||
121 | mutex_unlock(&read_lock); | ||
122 | |||
123 | return ret ? ret : copied; | ||
124 | } | ||
125 | |||
126 | static const struct file_operations fifo_fops = { | ||
127 | .owner = THIS_MODULE, | ||
128 | .read = fifo_read, | ||
129 | .write = fifo_write, | ||
130 | }; | ||
131 | |||
132 | static int __init example_init(void) | ||
133 | { | ||
134 | #ifdef DYNAMIC | ||
135 | int ret; | ||
136 | |||
137 | ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL); | ||
138 | if (ret) { | ||
139 | printk(KERN_ERR "error kfifo_alloc\n"); | ||
140 | return ret; | ||
141 | } | ||
142 | #else | ||
143 | INIT_KFIFO(test); | ||
144 | #endif | ||
145 | testfunc(); | ||
146 | |||
147 | if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) { | ||
148 | #ifdef DYNAMIC | ||
149 | kfifo_free(&test); | ||
150 | #endif | ||
151 | return -ENOMEM; | ||
152 | } | ||
153 | return 0; | ||
154 | } | ||
155 | |||
156 | static void __exit example_exit(void) | ||
157 | { | ||
158 | remove_proc_entry(PROC_FIFO, NULL); | ||
159 | #ifdef DYNAMIC | ||
160 | kfifo_free(&test); | ||
161 | #endif | ||
162 | } | ||
163 | |||
164 | module_init(example_init); | ||
165 | module_exit(example_exit); | ||
166 | MODULE_LICENSE("GPL"); | ||
167 | MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>"); | ||