thread-utils.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright 2023 Red Hat
  4 */
  5
  6#include "thread-utils.h"
  7
  8#include <asm/current.h>
  9#include <linux/delay.h>
 10#include <linux/kthread.h>
 11#include <linux/mutex.h>
 12#include <linux/types.h>
 13
 14#include "errors.h"
 15#include "logger.h"
 16#include "memory-alloc.h"
 17
 18static struct hlist_head thread_list;
 19static struct mutex thread_mutex;
 20
 21struct thread {
 22	void (*thread_function)(void *thread_data);
 23	void *thread_data;
 24	struct hlist_node thread_links;
 25	struct task_struct *thread_task;
 26	struct completion thread_done;
 27};
 28
 29void vdo_initialize_threads_mutex(void)
 30{
 31	mutex_init(&thread_mutex);
 32}
 33
 34static int thread_starter(void *arg)
 35{
 36	struct registered_thread allocating_thread;
 37	struct thread *thread = arg;
 38
 39	thread->thread_task = current;
 40	mutex_lock(&thread_mutex);
 41	hlist_add_head(&thread->thread_links, &thread_list);
 42	mutex_unlock(&thread_mutex);
 43	vdo_register_allocating_thread(&allocating_thread, NULL);
 44	thread->thread_function(thread->thread_data);
 45	vdo_unregister_allocating_thread();
 46	complete(&thread->thread_done);
 47	return 0;
 48}
 49
 50int vdo_create_thread(void (*thread_function)(void *), void *thread_data,
 51		      const char *name, struct thread **new_thread)
 52{
 53	char *name_colon = strchr(name, ':');
 54	char *my_name_colon = strchr(current->comm, ':');
 55	struct task_struct *task;
 56	struct thread *thread;
 57	int result;
 58
 59	result = vdo_allocate(1, struct thread, __func__, &thread);
 60	if (result != VDO_SUCCESS) {
 61		vdo_log_warning("Error allocating memory for %s", name);
 62		return result;
 63	}
 64
 65	thread->thread_function = thread_function;
 66	thread->thread_data = thread_data;
 67	init_completion(&thread->thread_done);
 68	/*
 69	 * Start the thread, with an appropriate thread name.
 70	 *
 71	 * If the name supplied contains a colon character, use that name. This causes uds module
 72	 * threads to have names like "uds:callbackW" and the main test runner thread to be named
 73	 * "zub:runtest".
 74	 *
 75	 * Otherwise if the current thread has a name containing a colon character, prefix the name
 76	 * supplied with the name of the current thread up to (and including) the colon character.
 77	 * Thus when the "kvdo0:dedupeQ" thread opens an index session, all the threads associated
 78	 * with that index will have names like "kvdo0:foo".
 79	 *
 80	 * Otherwise just use the name supplied. This should be a rare occurrence.
 81	 */
 82	if ((name_colon == NULL) && (my_name_colon != NULL)) {
 83		task = kthread_run(thread_starter, thread, "%.*s:%s",
 84				   (int) (my_name_colon - current->comm), current->comm,
 85				   name);
 86	} else {
 87		task = kthread_run(thread_starter, thread, "%s", name);
 88	}
 89
 90	if (IS_ERR(task)) {
 91		vdo_free(thread);
 92		return PTR_ERR(task);
 93	}
 94
 95	*new_thread = thread;
 96	return VDO_SUCCESS;
 97}
 98
 99void vdo_join_threads(struct thread *thread)
100{
101	while (wait_for_completion_interruptible(&thread->thread_done))
102		fsleep(1000);
103
104	mutex_lock(&thread_mutex);
105	hlist_del(&thread->thread_links);
106	mutex_unlock(&thread_mutex);
107	vdo_free(thread);
108}