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
18 static struct hlist_head thread_list;
19 static struct mutex thread_mutex;
20
21 struct 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
vdo_initialize_threads_mutex(void)29 void vdo_initialize_threads_mutex(void)
30 {
31 mutex_init(&thread_mutex);
32 }
33
thread_starter(void * arg)34 static 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
vdo_create_thread(void (* thread_function)(void *),void * thread_data,const char * name,struct thread ** new_thread)50 int 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
vdo_join_threads(struct thread * thread)99 void 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