Merge tag 'ioapic-cleanups-for-tip' of git://git.kernel.org/pub/scm/linux/kernel...
[platform/adaptation/renesas_rcar/renesas_kernel.git] / kernel / smpboot.c
1 /*
2  * Common SMP CPU bringup/teardown functions
3  */
4 #include <linux/cpu.h>
5 #include <linux/err.h>
6 #include <linux/smp.h>
7 #include <linux/init.h>
8 #include <linux/list.h>
9 #include <linux/slab.h>
10 #include <linux/sched.h>
11 #include <linux/export.h>
12 #include <linux/percpu.h>
13 #include <linux/kthread.h>
14 #include <linux/smpboot.h>
15
16 #include "smpboot.h"
17
18 #ifdef CONFIG_SMP
19
20 #ifdef CONFIG_GENERIC_SMP_IDLE_THREAD
21 /*
22  * For the hotplug case we keep the task structs around and reuse
23  * them.
24  */
25 static DEFINE_PER_CPU(struct task_struct *, idle_threads);
26
27 struct task_struct * __cpuinit idle_thread_get(unsigned int cpu)
28 {
29         struct task_struct *tsk = per_cpu(idle_threads, cpu);
30
31         if (!tsk)
32                 return ERR_PTR(-ENOMEM);
33         init_idle(tsk, cpu);
34         return tsk;
35 }
36
37 void __init idle_thread_set_boot_cpu(void)
38 {
39         per_cpu(idle_threads, smp_processor_id()) = current;
40 }
41
42 /**
43  * idle_init - Initialize the idle thread for a cpu
44  * @cpu:        The cpu for which the idle thread should be initialized
45  *
46  * Creates the thread if it does not exist.
47  */
48 static inline void idle_init(unsigned int cpu)
49 {
50         struct task_struct *tsk = per_cpu(idle_threads, cpu);
51
52         if (!tsk) {
53                 tsk = fork_idle(cpu);
54                 if (IS_ERR(tsk))
55                         pr_err("SMP: fork_idle() failed for CPU %u\n", cpu);
56                 else
57                         per_cpu(idle_threads, cpu) = tsk;
58         }
59 }
60
61 /**
62  * idle_threads_init - Initialize idle threads for all cpus
63  */
64 void __init idle_threads_init(void)
65 {
66         unsigned int cpu, boot_cpu;
67
68         boot_cpu = smp_processor_id();
69
70         for_each_possible_cpu(cpu) {
71                 if (cpu != boot_cpu)
72                         idle_init(cpu);
73         }
74 }
75 #endif
76
77 #endif /* #ifdef CONFIG_SMP */
78
79 static LIST_HEAD(hotplug_threads);
80 static DEFINE_MUTEX(smpboot_threads_lock);
81
82 struct smpboot_thread_data {
83         unsigned int                    cpu;
84         unsigned int                    status;
85         struct smp_hotplug_thread       *ht;
86 };
87
88 enum {
89         HP_THREAD_NONE = 0,
90         HP_THREAD_ACTIVE,
91         HP_THREAD_PARKED,
92 };
93
94 /**
95  * smpboot_thread_fn - percpu hotplug thread loop function
96  * @data:       thread data pointer
97  *
98  * Checks for thread stop and park conditions. Calls the necessary
99  * setup, cleanup, park and unpark functions for the registered
100  * thread.
101  *
102  * Returns 1 when the thread should exit, 0 otherwise.
103  */
104 static int smpboot_thread_fn(void *data)
105 {
106         struct smpboot_thread_data *td = data;
107         struct smp_hotplug_thread *ht = td->ht;
108
109         while (1) {
110                 set_current_state(TASK_INTERRUPTIBLE);
111                 preempt_disable();
112                 if (kthread_should_stop()) {
113                         set_current_state(TASK_RUNNING);
114                         preempt_enable();
115                         if (ht->cleanup)
116                                 ht->cleanup(td->cpu, cpu_online(td->cpu));
117                         kfree(td);
118                         return 0;
119                 }
120
121                 if (kthread_should_park()) {
122                         __set_current_state(TASK_RUNNING);
123                         preempt_enable();
124                         if (ht->park && td->status == HP_THREAD_ACTIVE) {
125                                 BUG_ON(td->cpu != smp_processor_id());
126                                 ht->park(td->cpu);
127                                 td->status = HP_THREAD_PARKED;
128                         }
129                         kthread_parkme();
130                         /* We might have been woken for stop */
131                         continue;
132                 }
133
134                 BUG_ON(td->cpu != smp_processor_id());
135
136                 /* Check for state change setup */
137                 switch (td->status) {
138                 case HP_THREAD_NONE:
139                         preempt_enable();
140                         if (ht->setup)
141                                 ht->setup(td->cpu);
142                         td->status = HP_THREAD_ACTIVE;
143                         preempt_disable();
144                         break;
145                 case HP_THREAD_PARKED:
146                         preempt_enable();
147                         if (ht->unpark)
148                                 ht->unpark(td->cpu);
149                         td->status = HP_THREAD_ACTIVE;
150                         preempt_disable();
151                         break;
152                 }
153
154                 if (!ht->thread_should_run(td->cpu)) {
155                         preempt_enable();
156                         schedule();
157                 } else {
158                         set_current_state(TASK_RUNNING);
159                         preempt_enable();
160                         ht->thread_fn(td->cpu);
161                 }
162         }
163 }
164
165 static int
166 __smpboot_create_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
167 {
168         struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
169         struct smpboot_thread_data *td;
170
171         if (tsk)
172                 return 0;
173
174         td = kzalloc_node(sizeof(*td), GFP_KERNEL, cpu_to_node(cpu));
175         if (!td)
176                 return -ENOMEM;
177         td->cpu = cpu;
178         td->ht = ht;
179
180         tsk = kthread_create_on_cpu(smpboot_thread_fn, td, cpu,
181                                     ht->thread_comm);
182         if (IS_ERR(tsk)) {
183                 kfree(td);
184                 return PTR_ERR(tsk);
185         }
186
187         get_task_struct(tsk);
188         *per_cpu_ptr(ht->store, cpu) = tsk;
189         return 0;
190 }
191
192 int smpboot_create_threads(unsigned int cpu)
193 {
194         struct smp_hotplug_thread *cur;
195         int ret = 0;
196
197         mutex_lock(&smpboot_threads_lock);
198         list_for_each_entry(cur, &hotplug_threads, list) {
199                 ret = __smpboot_create_thread(cur, cpu);
200                 if (ret)
201                         break;
202         }
203         mutex_unlock(&smpboot_threads_lock);
204         return ret;
205 }
206
207 static void smpboot_unpark_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
208 {
209         struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
210
211         kthread_unpark(tsk);
212 }
213
214 void smpboot_unpark_threads(unsigned int cpu)
215 {
216         struct smp_hotplug_thread *cur;
217
218         mutex_lock(&smpboot_threads_lock);
219         list_for_each_entry(cur, &hotplug_threads, list)
220                 smpboot_unpark_thread(cur, cpu);
221         mutex_unlock(&smpboot_threads_lock);
222 }
223
224 static void smpboot_park_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
225 {
226         struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
227
228         if (tsk)
229                 kthread_park(tsk);
230 }
231
232 void smpboot_park_threads(unsigned int cpu)
233 {
234         struct smp_hotplug_thread *cur;
235
236         mutex_lock(&smpboot_threads_lock);
237         list_for_each_entry_reverse(cur, &hotplug_threads, list)
238                 smpboot_park_thread(cur, cpu);
239         mutex_unlock(&smpboot_threads_lock);
240 }
241
242 static void smpboot_destroy_threads(struct smp_hotplug_thread *ht)
243 {
244         unsigned int cpu;
245
246         /* We need to destroy also the parked threads of offline cpus */
247         for_each_possible_cpu(cpu) {
248                 struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
249
250                 if (tsk) {
251                         kthread_stop(tsk);
252                         put_task_struct(tsk);
253                         *per_cpu_ptr(ht->store, cpu) = NULL;
254                 }
255         }
256 }
257
258 /**
259  * smpboot_register_percpu_thread - Register a per_cpu thread related to hotplug
260  * @plug_thread:        Hotplug thread descriptor
261  *
262  * Creates and starts the threads on all online cpus.
263  */
264 int smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread)
265 {
266         unsigned int cpu;
267         int ret = 0;
268
269         mutex_lock(&smpboot_threads_lock);
270         for_each_online_cpu(cpu) {
271                 ret = __smpboot_create_thread(plug_thread, cpu);
272                 if (ret) {
273                         smpboot_destroy_threads(plug_thread);
274                         goto out;
275                 }
276                 smpboot_unpark_thread(plug_thread, cpu);
277         }
278         list_add(&plug_thread->list, &hotplug_threads);
279 out:
280         mutex_unlock(&smpboot_threads_lock);
281         return ret;
282 }
283 EXPORT_SYMBOL_GPL(smpboot_register_percpu_thread);
284
285 /**
286  * smpboot_unregister_percpu_thread - Unregister a per_cpu thread related to hotplug
287  * @plug_thread:        Hotplug thread descriptor
288  *
289  * Stops all threads on all possible cpus.
290  */
291 void smpboot_unregister_percpu_thread(struct smp_hotplug_thread *plug_thread)
292 {
293         get_online_cpus();
294         mutex_lock(&smpboot_threads_lock);
295         list_del(&plug_thread->list);
296         smpboot_destroy_threads(plug_thread);
297         mutex_unlock(&smpboot_threads_lock);
298         put_online_cpus();
299 }
300 EXPORT_SYMBOL_GPL(smpboot_unregister_percpu_thread);