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}
109