From 4352b8aee98005853aa63f57d6377282de17a33f Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 23 Aug 2026 13:28:57 -0700 Subject: Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ... --- samples/kfifo/bytestream-example.c | 196 +++++++++++++++++++++++++++++++++++++ 1 file changed, 196 insertions(+) create mode 100644 samples/kfifo/bytestream-example.c (limited to 'samples/kfifo/bytestream-example.c') diff --git a/samples/kfifo/bytestream-example.c b/samples/kfifo/bytestream-example.c new file mode 100644 index 000000000..4ae29a12c --- /dev/null +++ b/samples/kfifo/bytestream-example.c @@ -0,0 +1,196 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Sample kfifo byte stream implementation + * + * Copyright (C) 2010 Stefani Seibold + */ + +#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_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 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_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; + } +#else + INIT_KFIFO(test); +#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_DESCRIPTION("Sample kfifo byte stream implementation"); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Stefani Seibold "); -- cgit v1.3.1