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Diffstat (limited to 'samples/kfifo/inttype-example.c')
-rw-r--r-- | samples/kfifo/inttype-example.c | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/samples/kfifo/inttype-example.c b/samples/kfifo/inttype-example.c new file mode 100644 index 0000000000..c61482ba94 --- /dev/null +++ b/samples/kfifo/inttype-example.c @@ -0,0 +1,186 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Sample kfifo int type implementation + * + * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net> + */ + +#include <linux/init.h> +#include <linux/module.h> +#include <linux/proc_fs.h> +#include <linux/mutex.h> +#include <linux/kfifo.h> + +/* + * This module shows how to create a int type fifo. + */ + +/* fifo size in elements (ints) */ +#define FIFO_SIZE 32 + +/* name of the proc entry */ +#define PROC_FIFO "int-fifo" + +/* lock for procfs read access */ +static DEFINE_MUTEX(read_access); + +/* lock for procfs write access */ +static DEFINE_MUTEX(write_access); + +/* + * define DYNAMIC in this example for a dynamically allocated fifo. + * + * Otherwise the fifo storage will be a part of the fifo structure. + */ +#if 0 +#define DYNAMIC +#endif + +#ifdef DYNAMIC +static DECLARE_KFIFO_PTR(test, int); +#else +static DEFINE_KFIFO(test, int, FIFO_SIZE); +#endif + +static const int expected_result[FIFO_SIZE] = { + 3, 4, 5, 6, 7, 8, 9, 0, + 1, 20, 21, 22, 23, 24, 25, 26, + 27, 28, 29, 30, 31, 32, 33, 34, + 35, 36, 37, 38, 39, 40, 41, 42, +}; + +static int __init testfunc(void) +{ + int buf[6]; + int i, j; + unsigned int ret; + + printk(KERN_INFO "int fifo test start\n"); + + /* put values into the fifo */ + for (i = 0; i != 10; i++) + kfifo_put(&test, i); + + /* show the number of used elements */ + printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test)); + + /* get max of 2 elements from the fifo */ + ret = kfifo_out(&test, buf, 2); + printk(KERN_INFO "ret: %d\n", ret); + /* and put it back to the end of the fifo */ + ret = kfifo_in(&test, buf, ret); + printk(KERN_INFO "ret: %d\n", ret); + + /* skip first element of the fifo */ + printk(KERN_INFO "skip 1st element\n"); + kfifo_skip(&test); + + /* put values into the fifo until is full */ + for (i = 20; kfifo_put(&test, i); i++) + ; + + printk(KERN_INFO "queue len: %u\n", kfifo_len(&test)); + + /* show the first value without removing from the fifo */ + if (kfifo_peek(&test, &i)) + printk(KERN_INFO "%d\n", i); + + /* check the correctness of all values in the fifo */ + j = 0; + while (kfifo_get(&test, &i)) { + printk(KERN_INFO "item = %d\n", i); + if (i != expected_result[j++]) { + printk(KERN_WARNING "value mismatch: test failed\n"); + return -EIO; + } + } + if (j != ARRAY_SIZE(expected_result)) { + printk(KERN_WARNING "size mismatch: test failed\n"); + return -EIO; + } + printk(KERN_INFO "test passed\n"); + + return 0; +} + +static ssize_t fifo_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + int ret; + unsigned int copied; + + if (mutex_lock_interruptible(&write_access)) + return -ERESTARTSYS; + + ret = kfifo_from_user(&test, buf, count, &copied); + + mutex_unlock(&write_access); + if (ret) + return ret; + + return copied; +} + +static ssize_t fifo_read(struct file *file, char __user *buf, + size_t count, loff_t *ppos) +{ + int ret; + unsigned int copied; + + if (mutex_lock_interruptible(&read_access)) + return -ERESTARTSYS; + + ret = kfifo_to_user(&test, buf, count, &copied); + + mutex_unlock(&read_access); + if (ret) + return ret; + + return copied; +} + +static const struct proc_ops fifo_proc_ops = { + .proc_read = fifo_read, + .proc_write = fifo_write, + .proc_lseek = noop_llseek, +}; + +static int __init example_init(void) +{ +#ifdef DYNAMIC + int ret; + + ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL); + if (ret) { + printk(KERN_ERR "error kfifo_alloc\n"); + return ret; + } +#endif + if (testfunc() < 0) { +#ifdef DYNAMIC + kfifo_free(&test); +#endif + return -EIO; + } + + if (proc_create(PROC_FIFO, 0, NULL, &fifo_proc_ops) == NULL) { +#ifdef DYNAMIC + kfifo_free(&test); +#endif + return -ENOMEM; + } + return 0; +} + +static void __exit example_exit(void) +{ + remove_proc_entry(PROC_FIFO, NULL); +#ifdef DYNAMIC + kfifo_free(&test); +#endif +} + +module_init(example_init); +module_exit(example_exit); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>"); |