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Commit | Line | Data |
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1da177e4 LT |
1 | /* Kernel thread helper functions. |
2 | * Copyright (C) 2004 IBM Corporation, Rusty Russell. | |
3 | * | |
73c27992 | 4 | * Creation is done via kthreadd, so that we get a clean environment |
1da177e4 LT |
5 | * even if we're invoked from userspace (think modprobe, hotplug cpu, |
6 | * etc.). | |
7 | */ | |
8 | #include <linux/sched.h> | |
9 | #include <linux/kthread.h> | |
10 | #include <linux/completion.h> | |
11 | #include <linux/err.h> | |
58568d2a | 12 | #include <linux/cpuset.h> |
1da177e4 LT |
13 | #include <linux/unistd.h> |
14 | #include <linux/file.h> | |
15 | #include <linux/module.h> | |
97d1f15b | 16 | #include <linux/mutex.h> |
ad8d75ff | 17 | #include <trace/events/sched.h> |
1da177e4 | 18 | |
4f05b98d MS |
19 | #define KTHREAD_NICE_LEVEL (-5) |
20 | ||
73c27992 EB |
21 | static DEFINE_SPINLOCK(kthread_create_lock); |
22 | static LIST_HEAD(kthread_create_list); | |
23 | struct task_struct *kthreadd_task; | |
1da177e4 LT |
24 | |
25 | struct kthread_create_info | |
26 | { | |
73c27992 | 27 | /* Information passed to kthread() from kthreadd. */ |
1da177e4 LT |
28 | int (*threadfn)(void *data); |
29 | void *data; | |
1da177e4 | 30 | |
73c27992 | 31 | /* Result passed back to kthread_create() from kthreadd. */ |
1da177e4 LT |
32 | struct task_struct *result; |
33 | struct completion done; | |
65f27f38 | 34 | |
73c27992 | 35 | struct list_head list; |
1da177e4 LT |
36 | }; |
37 | ||
63706172 ON |
38 | struct kthread { |
39 | int should_stop; | |
40 | struct completion exited; | |
1da177e4 LT |
41 | }; |
42 | ||
63706172 ON |
43 | #define to_kthread(tsk) \ |
44 | container_of((tsk)->vfork_done, struct kthread, exited) | |
1da177e4 | 45 | |
9e37bd30 RD |
46 | /** |
47 | * kthread_should_stop - should this kthread return now? | |
48 | * | |
72fd4a35 | 49 | * When someone calls kthread_stop() on your kthread, it will be woken |
9e37bd30 RD |
50 | * and this will return true. You should then return, and your return |
51 | * value will be passed through to kthread_stop(). | |
52 | */ | |
1da177e4 LT |
53 | int kthread_should_stop(void) |
54 | { | |
63706172 | 55 | return to_kthread(current)->should_stop; |
1da177e4 LT |
56 | } |
57 | EXPORT_SYMBOL(kthread_should_stop); | |
58 | ||
1da177e4 LT |
59 | static int kthread(void *_create) |
60 | { | |
63706172 | 61 | /* Copy data: it's on kthread's stack */ |
1da177e4 | 62 | struct kthread_create_info *create = _create; |
63706172 ON |
63 | int (*threadfn)(void *data) = create->threadfn; |
64 | void *data = create->data; | |
65 | struct kthread self; | |
66 | int ret; | |
1da177e4 | 67 | |
63706172 ON |
68 | self.should_stop = 0; |
69 | init_completion(&self.exited); | |
70 | current->vfork_done = &self.exited; | |
1da177e4 | 71 | |
1da177e4 | 72 | /* OK, tell user we're spawned, wait for stop or wakeup */ |
a076e4bc | 73 | __set_current_state(TASK_UNINTERRUPTIBLE); |
3217ab97 | 74 | create->result = current; |
cdd140bd | 75 | complete(&create->done); |
1da177e4 LT |
76 | schedule(); |
77 | ||
63706172 ON |
78 | ret = -EINTR; |
79 | if (!self.should_stop) | |
1da177e4 LT |
80 | ret = threadfn(data); |
81 | ||
63706172 ON |
82 | /* we can't just return, we must preserve "self" on stack */ |
83 | do_exit(ret); | |
1da177e4 LT |
84 | } |
85 | ||
73c27992 | 86 | static void create_kthread(struct kthread_create_info *create) |
1da177e4 | 87 | { |
1da177e4 LT |
88 | int pid; |
89 | ||
90 | /* We want our own signal handler (we take no signals by default). */ | |
91 | pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); | |
cdd140bd | 92 | if (pid < 0) { |
1da177e4 | 93 | create->result = ERR_PTR(pid); |
cdd140bd ON |
94 | complete(&create->done); |
95 | } | |
1da177e4 LT |
96 | } |
97 | ||
9e37bd30 RD |
98 | /** |
99 | * kthread_create - create a kthread. | |
100 | * @threadfn: the function to run until signal_pending(current). | |
101 | * @data: data ptr for @threadfn. | |
102 | * @namefmt: printf-style name for the thread. | |
103 | * | |
104 | * Description: This helper function creates and names a kernel | |
105 | * thread. The thread will be stopped: use wake_up_process() to start | |
106 | * it. See also kthread_run(), kthread_create_on_cpu(). | |
107 | * | |
108 | * When woken, the thread will run @threadfn() with @data as its | |
72fd4a35 | 109 | * argument. @threadfn() can either call do_exit() directly if it is a |
9e37bd30 RD |
110 | * standalone thread for which noone will call kthread_stop(), or |
111 | * return when 'kthread_should_stop()' is true (which means | |
112 | * kthread_stop() has been called). The return value should be zero | |
113 | * or a negative error number; it will be passed to kthread_stop(). | |
114 | * | |
115 | * Returns a task_struct or ERR_PTR(-ENOMEM). | |
116 | */ | |
1da177e4 LT |
117 | struct task_struct *kthread_create(int (*threadfn)(void *data), |
118 | void *data, | |
119 | const char namefmt[], | |
120 | ...) | |
121 | { | |
122 | struct kthread_create_info create; | |
1da177e4 LT |
123 | |
124 | create.threadfn = threadfn; | |
125 | create.data = data; | |
1da177e4 | 126 | init_completion(&create.done); |
73c27992 EB |
127 | |
128 | spin_lock(&kthread_create_lock); | |
129 | list_add_tail(&create.list, &kthread_create_list); | |
73c27992 EB |
130 | spin_unlock(&kthread_create_lock); |
131 | ||
cbd9b67b | 132 | wake_up_process(kthreadd_task); |
73c27992 EB |
133 | wait_for_completion(&create.done); |
134 | ||
1da177e4 | 135 | if (!IS_ERR(create.result)) { |
1c99315b | 136 | struct sched_param param = { .sched_priority = 0 }; |
1da177e4 | 137 | va_list args; |
1c99315b | 138 | |
1da177e4 LT |
139 | va_start(args, namefmt); |
140 | vsnprintf(create.result->comm, sizeof(create.result->comm), | |
141 | namefmt, args); | |
142 | va_end(args); | |
1c99315b ON |
143 | /* |
144 | * root may have changed our (kthreadd's) priority or CPU mask. | |
145 | * The kernel thread should not inherit these properties. | |
146 | */ | |
147 | sched_setscheduler_nocheck(create.result, SCHED_NORMAL, ¶m); | |
148 | set_user_nice(create.result, KTHREAD_NICE_LEVEL); | |
149 | set_cpus_allowed_ptr(create.result, cpu_all_mask); | |
1da177e4 | 150 | } |
1da177e4 LT |
151 | return create.result; |
152 | } | |
153 | EXPORT_SYMBOL(kthread_create); | |
154 | ||
9e37bd30 RD |
155 | /** |
156 | * kthread_bind - bind a just-created kthread to a cpu. | |
157 | * @k: thread created by kthread_create(). | |
158 | * @cpu: cpu (might not be online, must be possible) for @k to run on. | |
159 | * | |
160 | * Description: This function is equivalent to set_cpus_allowed(), | |
161 | * except that @cpu doesn't need to be online, and the thread must be | |
72fd4a35 | 162 | * stopped (i.e., just returned from kthread_create()). |
9e37bd30 | 163 | */ |
1da177e4 LT |
164 | void kthread_bind(struct task_struct *k, unsigned int cpu) |
165 | { | |
293adee6 ON |
166 | /* Must have done schedule() in kthread() before we set_task_cpu */ |
167 | if (!wait_task_inactive(k, TASK_UNINTERRUPTIBLE)) { | |
a076e4bc ON |
168 | WARN_ON(1); |
169 | return; | |
170 | } | |
1da177e4 LT |
171 | set_task_cpu(k, cpu); |
172 | k->cpus_allowed = cpumask_of_cpu(cpu); | |
9f0e738f | 173 | k->rt.nr_cpus_allowed = 1; |
9985b0ba | 174 | k->flags |= PF_THREAD_BOUND; |
1da177e4 LT |
175 | } |
176 | EXPORT_SYMBOL(kthread_bind); | |
177 | ||
9e37bd30 RD |
178 | /** |
179 | * kthread_stop - stop a thread created by kthread_create(). | |
180 | * @k: thread created by kthread_create(). | |
181 | * | |
182 | * Sets kthread_should_stop() for @k to return true, wakes it, and | |
9ae26027 ON |
183 | * waits for it to exit. This can also be called after kthread_create() |
184 | * instead of calling wake_up_process(): the thread will exit without | |
185 | * calling threadfn(). | |
186 | * | |
187 | * If threadfn() may call do_exit() itself, the caller must ensure | |
188 | * task_struct can't go away. | |
9e37bd30 RD |
189 | * |
190 | * Returns the result of threadfn(), or %-EINTR if wake_up_process() | |
191 | * was never called. | |
192 | */ | |
1da177e4 LT |
193 | int kthread_stop(struct task_struct *k) |
194 | { | |
63706172 | 195 | struct kthread *kthread; |
1da177e4 LT |
196 | int ret; |
197 | ||
0a16b607 | 198 | trace_sched_kthread_stop(k); |
63706172 | 199 | get_task_struct(k); |
0a16b607 | 200 | |
63706172 ON |
201 | kthread = to_kthread(k); |
202 | barrier(); /* it might have exited */ | |
203 | if (k->vfork_done != NULL) { | |
204 | kthread->should_stop = 1; | |
205 | wake_up_process(k); | |
206 | wait_for_completion(&kthread->exited); | |
207 | } | |
208 | ret = k->exit_code; | |
1da177e4 | 209 | |
1da177e4 | 210 | put_task_struct(k); |
0a16b607 MD |
211 | trace_sched_kthread_stop_ret(ret); |
212 | ||
1da177e4 LT |
213 | return ret; |
214 | } | |
52e92e57 | 215 | EXPORT_SYMBOL(kthread_stop); |
1da177e4 | 216 | |
e804a4a4 | 217 | int kthreadd(void *unused) |
1da177e4 | 218 | { |
73c27992 | 219 | struct task_struct *tsk = current; |
1da177e4 | 220 | |
e804a4a4 | 221 | /* Setup a clean context for our children to inherit. */ |
73c27992 | 222 | set_task_comm(tsk, "kthreadd"); |
10ab825b | 223 | ignore_signals(tsk); |
4f05b98d | 224 | set_user_nice(tsk, KTHREAD_NICE_LEVEL); |
1a2142af | 225 | set_cpus_allowed_ptr(tsk, cpu_all_mask); |
58568d2a | 226 | set_mems_allowed(node_possible_map); |
73c27992 | 227 | |
ebb12db5 | 228 | current->flags |= PF_NOFREEZE | PF_FREEZER_NOSIG; |
73c27992 EB |
229 | |
230 | for (;;) { | |
231 | set_current_state(TASK_INTERRUPTIBLE); | |
232 | if (list_empty(&kthread_create_list)) | |
233 | schedule(); | |
234 | __set_current_state(TASK_RUNNING); | |
235 | ||
236 | spin_lock(&kthread_create_lock); | |
237 | while (!list_empty(&kthread_create_list)) { | |
238 | struct kthread_create_info *create; | |
239 | ||
240 | create = list_entry(kthread_create_list.next, | |
241 | struct kthread_create_info, list); | |
242 | list_del_init(&create->list); | |
243 | spin_unlock(&kthread_create_lock); | |
244 | ||
245 | create_kthread(create); | |
246 | ||
247 | spin_lock(&kthread_create_lock); | |
248 | } | |
249 | spin_unlock(&kthread_create_lock); | |
250 | } | |
251 | ||
252 | return 0; | |
253 | } |