/* * Sample kfifo byte stream implementation * * Copyright (C) 2010 Stefani Seibold * * Released under the GPL version 2 only. * */ #include #include #include #include #include /* * This module shows how to create a byte stream fifo. */ /* fifo size in elements (bytes) */ #define FIFO_SIZE 32 /* name of the proc entry */ #define PROC_FIFO "bytestream-fifo" /* lock for procfs read access */ static DEFINE_MUTEX(read_lock); /* lock for procfs write access */ static DEFINE_MUTEX(write_lock); /* * 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 struct kfifo test; #else static DECLARE_KFIFO(test, unsigned char, FIFO_SIZE); #endif static const unsigned char 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) { unsigned char buf[6]; unsigned char i, j; unsigned int ret; printk(KERN_INFO "byte stream fifo test start\n"); /* put string into the fifo */ kfifo_in(&test, "hello", 5); /* 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 5 bytes from the fifo */ i = kfifo_out(&test, buf, 5); printk(KERN_INFO "buf: %.*s\n", i, buf); /* 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_lock)) return -ERESTARTSYS; ret = kfifo_from_user(&test, buf, count, &copied); mutex_unlock(&write_lock); return ret ? ret : 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_lock)) return -ERESTARTSYS; ret = kfifo_to_user(&test, buf, count, &copied); mutex_unlock(&read_lock); return ret ? ret : copied; } static const struct file_operations fifo_fops = { .owner = THIS_MODULE, .read = fifo_read, .write = fifo_write, .llseek = 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; } #else INIT_KFIFO(test); #endif if (testfunc() < 0) { #ifdef DYNAMIC kfifo_free(&test); #endif return -EIO; } if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == 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 "); '30'>30space:mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 10:56:56 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 10:56:56 -0800
commit2c5d9555d6d937966d79d4c6529a5f7b9206e405 (patch)
tree4f3d220ea3aeaadcae0796c5456e0ef9a908071d /include/uapi/asm-generic/param.h
parent53cd1ad1a68fd10f677445e04ed63aa9ce39b36b (diff)
parent2ad5d52d42810bed95100a3d912679d8864421ec (diff)
Merge branch 'parisc-4.10-3' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux
Pull two parisc fixes from Helge Deller: "One fix to avoid usage of BITS_PER_LONG in user-space exported swab.h header which breaks compiling qemu, and one trivial fix for printk continuation in the parisc parport driver" * 'parisc-4.10-3' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux: parisc: Don't use BITS_PER_LONG in userspace-exported swab.h header parisc, parport_gsc: Fixes for printk continuation lines
Diffstat (limited to 'include/uapi/asm-generic/param.h')