Root/
1 | /* Kernel thread helper functions. |
2 | * Copyright (C) 2004 IBM Corporation, Rusty Russell. |
3 | * |
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/cpuset.h> |
13 | #include <linux/unistd.h> |
14 | #include <linux/file.h> |
15 | #include <linux/module.h> |
16 | #include <linux/mutex.h> |
17 | #include <trace/events/sched.h> |
18 | |
19 | #define KTHREAD_NICE_LEVEL (-5) |
20 | |
21 | static DEFINE_SPINLOCK(kthread_create_lock); |
22 | static LIST_HEAD(kthread_create_list); |
23 | struct task_struct *kthreadd_task; |
24 | |
25 | struct kthread_create_info |
26 | { |
27 | /* Information passed to kthread() from kthreadd. */ |
28 | int (*threadfn)(void *data); |
29 | void *data; |
30 | |
31 | /* Result passed back to kthread_create() from kthreadd. */ |
32 | struct task_struct *result; |
33 | struct completion done; |
34 | |
35 | struct list_head list; |
36 | }; |
37 | |
38 | struct kthread { |
39 | int should_stop; |
40 | struct completion exited; |
41 | }; |
42 | |
43 | #define to_kthread(tsk) \ |
44 | container_of((tsk)->vfork_done, struct kthread, exited) |
45 | |
46 | /** |
47 | * kthread_should_stop - should this kthread return now? |
48 | * |
49 | * When someone calls kthread_stop() on your kthread, it will be woken |
50 | * and this will return true. You should then return, and your return |
51 | * value will be passed through to kthread_stop(). |
52 | */ |
53 | int kthread_should_stop(void) |
54 | { |
55 | return to_kthread(current)->should_stop; |
56 | } |
57 | EXPORT_SYMBOL(kthread_should_stop); |
58 | |
59 | static int kthread(void *_create) |
60 | { |
61 | /* Copy data: it's on kthread's stack */ |
62 | struct kthread_create_info *create = _create; |
63 | int (*threadfn)(void *data) = create->threadfn; |
64 | void *data = create->data; |
65 | struct kthread self; |
66 | int ret; |
67 | |
68 | self.should_stop = 0; |
69 | init_completion(&self.exited); |
70 | current->vfork_done = &self.exited; |
71 | |
72 | /* OK, tell user we're spawned, wait for stop or wakeup */ |
73 | __set_current_state(TASK_UNINTERRUPTIBLE); |
74 | create->result = current; |
75 | complete(&create->done); |
76 | schedule(); |
77 | |
78 | ret = -EINTR; |
79 | if (!self.should_stop) |
80 | ret = threadfn(data); |
81 | |
82 | /* we can't just return, we must preserve "self" on stack */ |
83 | do_exit(ret); |
84 | } |
85 | |
86 | static void create_kthread(struct kthread_create_info *create) |
87 | { |
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); |
92 | if (pid < 0) { |
93 | create->result = ERR_PTR(pid); |
94 | complete(&create->done); |
95 | } |
96 | } |
97 | |
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 |
109 | * argument. @threadfn() can either call do_exit() directly if it is a |
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 | */ |
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; |
123 | |
124 | create.threadfn = threadfn; |
125 | create.data = data; |
126 | init_completion(&create.done); |
127 | |
128 | spin_lock(&kthread_create_lock); |
129 | list_add_tail(&create.list, &kthread_create_list); |
130 | spin_unlock(&kthread_create_lock); |
131 | |
132 | wake_up_process(kthreadd_task); |
133 | wait_for_completion(&create.done); |
134 | |
135 | if (!IS_ERR(create.result)) { |
136 | struct sched_param param = { .sched_priority = 0 }; |
137 | va_list args; |
138 | |
139 | va_start(args, namefmt); |
140 | vsnprintf(create.result->comm, sizeof(create.result->comm), |
141 | namefmt, args); |
142 | va_end(args); |
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); |
150 | } |
151 | return create.result; |
152 | } |
153 | EXPORT_SYMBOL(kthread_create); |
154 | |
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 |
162 | * stopped (i.e., just returned from kthread_create()). |
163 | */ |
164 | void kthread_bind(struct task_struct *k, unsigned int cpu) |
165 | { |
166 | /* Must have done schedule() in kthread() before we set_task_cpu */ |
167 | if (!wait_task_inactive(k, TASK_UNINTERRUPTIBLE)) { |
168 | WARN_ON(1); |
169 | return; |
170 | } |
171 | set_task_cpu(k, cpu); |
172 | k->cpus_allowed = cpumask_of_cpu(cpu); |
173 | k->rt.nr_cpus_allowed = 1; |
174 | k->flags |= PF_THREAD_BOUND; |
175 | } |
176 | EXPORT_SYMBOL(kthread_bind); |
177 | |
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 |
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. |
189 | * |
190 | * Returns the result of threadfn(), or %-EINTR if wake_up_process() |
191 | * was never called. |
192 | */ |
193 | int kthread_stop(struct task_struct *k) |
194 | { |
195 | struct kthread *kthread; |
196 | int ret; |
197 | |
198 | trace_sched_kthread_stop(k); |
199 | get_task_struct(k); |
200 | |
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; |
209 | |
210 | put_task_struct(k); |
211 | trace_sched_kthread_stop_ret(ret); |
212 | |
213 | return ret; |
214 | } |
215 | EXPORT_SYMBOL(kthread_stop); |
216 | |
217 | int kthreadd(void *unused) |
218 | { |
219 | struct task_struct *tsk = current; |
220 | |
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, KTHREAD_NICE_LEVEL); |
225 | set_cpus_allowed_ptr(tsk, cpu_all_mask); |
226 | set_mems_allowed(node_possible_map); |
227 | |
228 | current->flags |= PF_NOFREEZE | PF_FREEZER_NOSIG; |
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 | } |
254 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9