ACPI: thinkpad-acpi: revert new 2.6.23 CONFIG_THINKPAD_ACPI_INPUT_ENABLED option
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / kernel / kthread.c
blobdcfe724300eb3cd32c46c2d06de4fc92c7de070b
1 /* Kernel thread helper functions.
2 * Copyright (C) 2004 IBM Corporation, Rusty Russell.
4 * Creation is done via kthreadd, so that we get a clean environment
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>
12 #include <linux/unistd.h>
13 #include <linux/file.h>
14 #include <linux/module.h>
15 #include <linux/mutex.h>
16 #include <asm/semaphore.h>
18 static DEFINE_SPINLOCK(kthread_create_lock);
19 static LIST_HEAD(kthread_create_list);
20 struct task_struct *kthreadd_task;
22 struct kthread_create_info
24 /* Information passed to kthread() from kthreadd. */
25 int (*threadfn)(void *data);
26 void *data;
27 struct completion started;
29 /* Result passed back to kthread_create() from kthreadd. */
30 struct task_struct *result;
31 struct completion done;
33 struct list_head list;
36 struct kthread_stop_info
38 struct task_struct *k;
39 int err;
40 struct completion done;
43 /* Thread stopping is done by setthing this var: lock serializes
44 * multiple kthread_stop calls. */
45 static DEFINE_MUTEX(kthread_stop_lock);
46 static struct kthread_stop_info kthread_stop_info;
48 /**
49 * kthread_should_stop - should this kthread return now?
51 * When someone calls kthread_stop() on your kthread, it will be woken
52 * and this will return true. You should then return, and your return
53 * value will be passed through to kthread_stop().
55 int kthread_should_stop(void)
57 return (kthread_stop_info.k == current);
59 EXPORT_SYMBOL(kthread_should_stop);
61 static int kthread(void *_create)
63 struct kthread_create_info *create = _create;
64 int (*threadfn)(void *data);
65 void *data;
66 int ret = -EINTR;
68 /* Copy data: it's on kthread's stack */
69 threadfn = create->threadfn;
70 data = create->data;
72 /* OK, tell user we're spawned, wait for stop or wakeup */
73 __set_current_state(TASK_UNINTERRUPTIBLE);
74 complete(&create->started);
75 schedule();
77 if (!kthread_should_stop())
78 ret = threadfn(data);
80 /* It might have exited on its own, w/o kthread_stop. Check. */
81 if (kthread_should_stop()) {
82 kthread_stop_info.err = ret;
83 complete(&kthread_stop_info.done);
85 return 0;
88 static void create_kthread(struct kthread_create_info *create)
90 int pid;
92 /* We want our own signal handler (we take no signals by default). */
93 pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
94 if (pid < 0) {
95 create->result = ERR_PTR(pid);
96 } else {
97 wait_for_completion(&create->started);
98 read_lock(&tasklist_lock);
99 create->result = find_task_by_pid(pid);
100 read_unlock(&tasklist_lock);
102 complete(&create->done);
106 * kthread_create - create a kthread.
107 * @threadfn: the function to run until signal_pending(current).
108 * @data: data ptr for @threadfn.
109 * @namefmt: printf-style name for the thread.
111 * Description: This helper function creates and names a kernel
112 * thread. The thread will be stopped: use wake_up_process() to start
113 * it. See also kthread_run(), kthread_create_on_cpu().
115 * When woken, the thread will run @threadfn() with @data as its
116 * argument. @threadfn() can either call do_exit() directly if it is a
117 * standalone thread for which noone will call kthread_stop(), or
118 * return when 'kthread_should_stop()' is true (which means
119 * kthread_stop() has been called). The return value should be zero
120 * or a negative error number; it will be passed to kthread_stop().
122 * Returns a task_struct or ERR_PTR(-ENOMEM).
124 struct task_struct *kthread_create(int (*threadfn)(void *data),
125 void *data,
126 const char namefmt[],
127 ...)
129 struct kthread_create_info create;
131 create.threadfn = threadfn;
132 create.data = data;
133 init_completion(&create.started);
134 init_completion(&create.done);
136 spin_lock(&kthread_create_lock);
137 list_add_tail(&create.list, &kthread_create_list);
138 wake_up_process(kthreadd_task);
139 spin_unlock(&kthread_create_lock);
141 wait_for_completion(&create.done);
143 if (!IS_ERR(create.result)) {
144 va_list args;
145 va_start(args, namefmt);
146 vsnprintf(create.result->comm, sizeof(create.result->comm),
147 namefmt, args);
148 va_end(args);
150 return create.result;
152 EXPORT_SYMBOL(kthread_create);
155 * kthread_bind - bind a just-created kthread to a cpu.
156 * @k: thread created by kthread_create().
157 * @cpu: cpu (might not be online, must be possible) for @k to run on.
159 * Description: This function is equivalent to set_cpus_allowed(),
160 * except that @cpu doesn't need to be online, and the thread must be
161 * stopped (i.e., just returned from kthread_create()).
163 void kthread_bind(struct task_struct *k, unsigned int cpu)
165 if (k->state != TASK_UNINTERRUPTIBLE) {
166 WARN_ON(1);
167 return;
169 /* Must have done schedule() in kthread() before we set_task_cpu */
170 wait_task_inactive(k);
171 set_task_cpu(k, cpu);
172 k->cpus_allowed = cpumask_of_cpu(cpu);
174 EXPORT_SYMBOL(kthread_bind);
177 * kthread_stop - stop a thread created by kthread_create().
178 * @k: thread created by kthread_create().
180 * Sets kthread_should_stop() for @k to return true, wakes it, and
181 * waits for it to exit. Your threadfn() must not call do_exit()
182 * itself if you use this function! This can also be called after
183 * kthread_create() instead of calling wake_up_process(): the thread
184 * will exit without calling threadfn().
186 * Returns the result of threadfn(), or %-EINTR if wake_up_process()
187 * was never called.
189 int kthread_stop(struct task_struct *k)
191 int ret;
193 mutex_lock(&kthread_stop_lock);
195 /* It could exit after stop_info.k set, but before wake_up_process. */
196 get_task_struct(k);
198 /* Must init completion *before* thread sees kthread_stop_info.k */
199 init_completion(&kthread_stop_info.done);
200 smp_wmb();
202 /* Now set kthread_should_stop() to true, and wake it up. */
203 kthread_stop_info.k = k;
204 wake_up_process(k);
205 put_task_struct(k);
207 /* Once it dies, reset stop ptr, gather result and we're done. */
208 wait_for_completion(&kthread_stop_info.done);
209 kthread_stop_info.k = NULL;
210 ret = kthread_stop_info.err;
211 mutex_unlock(&kthread_stop_lock);
213 return ret;
215 EXPORT_SYMBOL(kthread_stop);
217 int kthreadd(void *unused)
219 struct task_struct *tsk = current;
221 /* Setup a clean context for our children to inherit. */
222 set_task_comm(tsk, "kthreadd");
223 ignore_signals(tsk);
224 set_user_nice(tsk, -5);
225 set_cpus_allowed(tsk, CPU_MASK_ALL);
227 current->flags |= PF_NOFREEZE;
229 for (;;) {
230 set_current_state(TASK_INTERRUPTIBLE);
231 if (list_empty(&kthread_create_list))
232 schedule();
233 __set_current_state(TASK_RUNNING);
235 spin_lock(&kthread_create_lock);
236 while (!list_empty(&kthread_create_list)) {
237 struct kthread_create_info *create;
239 create = list_entry(kthread_create_list.next,
240 struct kthread_create_info, list);
241 list_del_init(&create->list);
242 spin_unlock(&kthread_create_lock);
244 create_kthread(create);
246 spin_lock(&kthread_create_lock);
248 spin_unlock(&kthread_create_lock);
251 return 0;