Commit | Line | Data |
---|---|---|
3d442233 JA |
1 | /* |
2 | * Generic helpers for smp ipi calls | |
3 | * | |
4 | * (C) Jens Axboe <jens.axboe@oracle.com> 2008 | |
5 | * | |
6 | */ | |
7 | #include <linux/init.h> | |
8 | #include <linux/module.h> | |
9 | #include <linux/percpu.h> | |
10 | #include <linux/rcupdate.h> | |
59190f42 | 11 | #include <linux/rculist.h> |
3d442233 | 12 | #include <linux/smp.h> |
8969a5ed | 13 | #include <linux/cpu.h> |
3d442233 JA |
14 | |
15 | static DEFINE_PER_CPU(struct call_single_queue, call_single_queue); | |
8969a5ed PZ |
16 | |
17 | static struct { | |
18 | struct list_head queue; | |
19 | spinlock_t lock; | |
20 | } call_function __cacheline_aligned_in_smp = { | |
21 | .queue = LIST_HEAD_INIT(call_function.queue), | |
22 | .lock = __SPIN_LOCK_UNLOCKED(call_function.lock), | |
23 | }; | |
3d442233 JA |
24 | |
25 | enum { | |
6e275637 | 26 | CSD_FLAG_LOCK = 0x01, |
3d442233 JA |
27 | }; |
28 | ||
29 | struct call_function_data { | |
30 | struct call_single_data csd; | |
31 | spinlock_t lock; | |
32 | unsigned int refs; | |
8969a5ed | 33 | cpumask_var_t cpumask; |
3d442233 JA |
34 | }; |
35 | ||
36 | struct call_single_queue { | |
37 | struct list_head list; | |
38 | spinlock_t lock; | |
39 | }; | |
40 | ||
8969a5ed PZ |
41 | static DEFINE_PER_CPU(struct call_function_data, cfd_data) = { |
42 | .lock = __SPIN_LOCK_UNLOCKED(cfd_data.lock), | |
43 | }; | |
44 | ||
45 | static int | |
46 | hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu) | |
47 | { | |
48 | long cpu = (long)hcpu; | |
49 | struct call_function_data *cfd = &per_cpu(cfd_data, cpu); | |
50 | ||
51 | switch (action) { | |
52 | case CPU_UP_PREPARE: | |
53 | case CPU_UP_PREPARE_FROZEN: | |
54 | if (!alloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL, | |
55 | cpu_to_node(cpu))) | |
56 | return NOTIFY_BAD; | |
57 | break; | |
58 | ||
59 | #ifdef CONFIG_CPU_HOTPLUG | |
60 | case CPU_UP_CANCELED: | |
61 | case CPU_UP_CANCELED_FROZEN: | |
62 | ||
63 | case CPU_DEAD: | |
64 | case CPU_DEAD_FROZEN: | |
65 | free_cpumask_var(cfd->cpumask); | |
66 | break; | |
67 | #endif | |
68 | }; | |
69 | ||
70 | return NOTIFY_OK; | |
71 | } | |
72 | ||
73 | static struct notifier_block __cpuinitdata hotplug_cfd_notifier = { | |
74 | .notifier_call = hotplug_cfd, | |
75 | }; | |
76 | ||
7babe8db | 77 | static int __cpuinit init_call_single_data(void) |
3d442233 | 78 | { |
8969a5ed | 79 | void *cpu = (void *)(long)smp_processor_id(); |
3d442233 JA |
80 | int i; |
81 | ||
82 | for_each_possible_cpu(i) { | |
83 | struct call_single_queue *q = &per_cpu(call_single_queue, i); | |
84 | ||
85 | spin_lock_init(&q->lock); | |
86 | INIT_LIST_HEAD(&q->list); | |
87 | } | |
8969a5ed PZ |
88 | |
89 | hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu); | |
90 | register_cpu_notifier(&hotplug_cfd_notifier); | |
91 | ||
7babe8db | 92 | return 0; |
3d442233 | 93 | } |
7babe8db | 94 | early_initcall(init_call_single_data); |
3d442233 | 95 | |
8969a5ed PZ |
96 | /* |
97 | * csd_lock/csd_unlock used to serialize access to per-cpu csd resources | |
98 | * | |
99 | * For non-synchronous ipi calls the csd can still be in use by the previous | |
100 | * function call. For multi-cpu calls its even more interesting as we'll have | |
101 | * to ensure no other cpu is observing our csd. | |
102 | */ | |
6e275637 | 103 | static void csd_lock_wait(struct call_single_data *data) |
8969a5ed PZ |
104 | { |
105 | while (data->flags & CSD_FLAG_LOCK) | |
106 | cpu_relax(); | |
6e275637 PZ |
107 | } |
108 | ||
109 | static void csd_lock(struct call_single_data *data) | |
110 | { | |
111 | csd_lock_wait(data); | |
8969a5ed PZ |
112 | data->flags = CSD_FLAG_LOCK; |
113 | ||
114 | /* | |
115 | * prevent CPU from reordering the above assignment to ->flags | |
116 | * with any subsequent assignments to other fields of the | |
117 | * specified call_single_data structure. | |
118 | */ | |
119 | ||
120 | smp_mb(); | |
121 | } | |
122 | ||
123 | static void csd_unlock(struct call_single_data *data) | |
124 | { | |
125 | WARN_ON(!(data->flags & CSD_FLAG_LOCK)); | |
126 | /* | |
127 | * ensure we're all done before releasing data | |
128 | */ | |
129 | smp_mb(); | |
130 | data->flags &= ~CSD_FLAG_LOCK; | |
3d442233 JA |
131 | } |
132 | ||
133 | /* | |
134 | * Insert a previously allocated call_single_data element for execution | |
135 | * on the given CPU. data must already have ->func, ->info, and ->flags set. | |
136 | */ | |
6e275637 PZ |
137 | static |
138 | void generic_exec_single(int cpu, struct call_single_data *data, int wait) | |
3d442233 JA |
139 | { |
140 | struct call_single_queue *dst = &per_cpu(call_single_queue, cpu); | |
3d442233 | 141 | unsigned long flags; |
6e275637 | 142 | int ipi; |
3d442233 JA |
143 | |
144 | spin_lock_irqsave(&dst->lock, flags); | |
145 | ipi = list_empty(&dst->list); | |
146 | list_add_tail(&data->list, &dst->list); | |
147 | spin_unlock_irqrestore(&dst->lock, flags); | |
148 | ||
561920a0 | 149 | /* |
15d0d3b3 NP |
150 | * The list addition should be visible before sending the IPI |
151 | * handler locks the list to pull the entry off it because of | |
152 | * normal cache coherency rules implied by spinlocks. | |
153 | * | |
154 | * If IPIs can go out of order to the cache coherency protocol | |
155 | * in an architecture, sufficient synchronisation should be added | |
156 | * to arch code to make it appear to obey cache coherency WRT | |
157 | * locking and barrier primitives. Generic code isn't really equipped | |
158 | * to do the right thing... | |
561920a0 | 159 | */ |
561920a0 | 160 | |
3d442233 JA |
161 | if (ipi) |
162 | arch_send_call_function_single_ipi(cpu); | |
163 | ||
164 | if (wait) | |
6e275637 | 165 | csd_lock_wait(data); |
3d442233 JA |
166 | } |
167 | ||
168 | /* | |
169 | * Invoked by arch to handle an IPI for call function. Must be called with | |
170 | * interrupts disabled. | |
171 | */ | |
172 | void generic_smp_call_function_interrupt(void) | |
173 | { | |
174 | struct call_function_data *data; | |
175 | int cpu = get_cpu(); | |
176 | ||
15d0d3b3 NP |
177 | /* |
178 | * Ensure entry is visible on call_function_queue after we have | |
179 | * entered the IPI. See comment in smp_call_function_many. | |
180 | * If we don't have this, then we may miss an entry on the list | |
181 | * and never get another IPI to process it. | |
182 | */ | |
183 | smp_mb(); | |
184 | ||
3d442233 JA |
185 | /* |
186 | * It's ok to use list_for_each_rcu() here even though we may delete | |
187 | * 'pos', since list_del_rcu() doesn't clear ->next | |
188 | */ | |
8969a5ed | 189 | list_for_each_entry_rcu(data, &call_function.queue, csd.list) { |
3d442233 JA |
190 | int refs; |
191 | ||
8969a5ed PZ |
192 | spin_lock(&data->lock); |
193 | if (!cpumask_test_cpu(cpu, data->cpumask)) { | |
194 | spin_unlock(&data->lock); | |
3d442233 | 195 | continue; |
8969a5ed PZ |
196 | } |
197 | cpumask_clear_cpu(cpu, data->cpumask); | |
198 | spin_unlock(&data->lock); | |
3d442233 JA |
199 | |
200 | data->csd.func(data->csd.info); | |
201 | ||
202 | spin_lock(&data->lock); | |
3d442233 | 203 | WARN_ON(data->refs == 0); |
8969a5ed PZ |
204 | refs = --data->refs; |
205 | if (!refs) { | |
206 | spin_lock(&call_function.lock); | |
207 | list_del_rcu(&data->csd.list); | |
208 | spin_unlock(&call_function.lock); | |
209 | } | |
3d442233 JA |
210 | spin_unlock(&data->lock); |
211 | ||
212 | if (refs) | |
213 | continue; | |
214 | ||
8969a5ed | 215 | csd_unlock(&data->csd); |
3d442233 | 216 | } |
3d442233 JA |
217 | |
218 | put_cpu(); | |
219 | } | |
220 | ||
221 | /* | |
222 | * Invoked by arch to handle an IPI for call function single. Must be called | |
223 | * from the arch with interrupts disabled. | |
224 | */ | |
225 | void generic_smp_call_function_single_interrupt(void) | |
226 | { | |
227 | struct call_single_queue *q = &__get_cpu_var(call_single_queue); | |
228 | LIST_HEAD(list); | |
15d0d3b3 | 229 | unsigned int data_flags; |
3d442233 | 230 | |
15d0d3b3 NP |
231 | spin_lock(&q->lock); |
232 | list_replace_init(&q->list, &list); | |
233 | spin_unlock(&q->lock); | |
3d442233 | 234 | |
15d0d3b3 NP |
235 | while (!list_empty(&list)) { |
236 | struct call_single_data *data; | |
3d442233 | 237 | |
15d0d3b3 NP |
238 | data = list_entry(list.next, struct call_single_data, |
239 | list); | |
240 | list_del(&data->list); | |
3d442233 | 241 | |
3d442233 | 242 | /* |
15d0d3b3 NP |
243 | * 'data' can be invalid after this call if |
244 | * flags == 0 (when called through | |
245 | * generic_exec_single(), so save them away before | |
246 | * making the call. | |
3d442233 | 247 | */ |
15d0d3b3 NP |
248 | data_flags = data->flags; |
249 | ||
250 | data->func(data->info); | |
251 | ||
8969a5ed PZ |
252 | /* |
253 | * Unlocked CSDs are valid through generic_exec_single() | |
254 | */ | |
255 | if (data_flags & CSD_FLAG_LOCK) | |
256 | csd_unlock(data); | |
3d442233 JA |
257 | } |
258 | } | |
259 | ||
d7240b98 SR |
260 | static DEFINE_PER_CPU(struct call_single_data, csd_data); |
261 | ||
3d442233 JA |
262 | /* |
263 | * smp_call_function_single - Run a function on a specific CPU | |
264 | * @func: The function to run. This must be fast and non-blocking. | |
265 | * @info: An arbitrary pointer to pass to the function. | |
3d442233 JA |
266 | * @wait: If true, wait until function has completed on other CPUs. |
267 | * | |
268 | * Returns 0 on success, else a negative status code. Note that @wait | |
269 | * will be implicitly turned on in case of allocation failures, since | |
270 | * we fall back to on-stack allocation. | |
271 | */ | |
272 | int smp_call_function_single(int cpu, void (*func) (void *info), void *info, | |
8691e5a8 | 273 | int wait) |
3d442233 | 274 | { |
8969a5ed PZ |
275 | struct call_single_data d = { |
276 | .flags = 0, | |
277 | }; | |
3d442233 | 278 | unsigned long flags; |
f73be6de PA |
279 | /* prevent preemption and reschedule on another processor, |
280 | as well as CPU removal */ | |
3d442233 | 281 | int me = get_cpu(); |
f73be6de | 282 | int err = 0; |
3d442233 JA |
283 | |
284 | /* Can deadlock when called with interrupts disabled */ | |
285 | WARN_ON(irqs_disabled()); | |
286 | ||
287 | if (cpu == me) { | |
288 | local_irq_save(flags); | |
289 | func(info); | |
290 | local_irq_restore(flags); | |
4f4b6c1a | 291 | } else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) { |
6e275637 | 292 | struct call_single_data *data = &d; |
3d442233 | 293 | |
6e275637 | 294 | if (!wait) |
8969a5ed | 295 | data = &__get_cpu_var(csd_data); |
6e275637 PZ |
296 | |
297 | csd_lock(data); | |
3d442233 JA |
298 | |
299 | data->func = func; | |
300 | data->info = info; | |
6e275637 | 301 | generic_exec_single(cpu, data, wait); |
f73be6de PA |
302 | } else { |
303 | err = -ENXIO; /* CPU not online */ | |
3d442233 JA |
304 | } |
305 | ||
306 | put_cpu(); | |
f73be6de | 307 | return err; |
3d442233 JA |
308 | } |
309 | EXPORT_SYMBOL(smp_call_function_single); | |
310 | ||
311 | /** | |
312 | * __smp_call_function_single(): Run a function on another CPU | |
313 | * @cpu: The CPU to run on. | |
314 | * @data: Pre-allocated and setup data structure | |
315 | * | |
316 | * Like smp_call_function_single(), but allow caller to pass in a pre-allocated | |
317 | * data structure. Useful for embedding @data inside other structures, for | |
318 | * instance. | |
319 | * | |
320 | */ | |
6e275637 PZ |
321 | void __smp_call_function_single(int cpu, struct call_single_data *data, |
322 | int wait) | |
3d442233 | 323 | { |
6e275637 PZ |
324 | csd_lock(data); |
325 | ||
3d442233 | 326 | /* Can deadlock when called with interrupts disabled */ |
6e275637 | 327 | WARN_ON(wait && irqs_disabled()); |
3d442233 | 328 | |
6e275637 | 329 | generic_exec_single(cpu, data, wait); |
3d442233 JA |
330 | } |
331 | ||
ce47d974 RR |
332 | /* FIXME: Shim for archs using old arch_send_call_function_ipi API. */ |
333 | #ifndef arch_send_call_function_ipi_mask | |
334 | #define arch_send_call_function_ipi_mask(maskp) \ | |
335 | arch_send_call_function_ipi(*(maskp)) | |
336 | #endif | |
337 | ||
3d442233 | 338 | /** |
54b11e6d RR |
339 | * smp_call_function_many(): Run a function on a set of other CPUs. |
340 | * @mask: The set of cpus to run on (only runs on online subset). | |
3d442233 JA |
341 | * @func: The function to run. This must be fast and non-blocking. |
342 | * @info: An arbitrary pointer to pass to the function. | |
343 | * @wait: If true, wait (atomically) until function has completed on other CPUs. | |
344 | * | |
3d442233 JA |
345 | * If @wait is true, then returns once @func has returned. Note that @wait |
346 | * will be implicitly turned on in case of allocation failures, since | |
347 | * we fall back to on-stack allocation. | |
348 | * | |
349 | * You must not call this function with disabled interrupts or from a | |
350 | * hardware interrupt handler or from a bottom half handler. Preemption | |
351 | * must be disabled when calling this function. | |
352 | */ | |
54b11e6d RR |
353 | void smp_call_function_many(const struct cpumask *mask, |
354 | void (*func)(void *), void *info, | |
355 | bool wait) | |
3d442233 | 356 | { |
54b11e6d | 357 | struct call_function_data *data; |
3d442233 | 358 | unsigned long flags; |
8969a5ed | 359 | int cpu, next_cpu, me = smp_processor_id(); |
3d442233 JA |
360 | |
361 | /* Can deadlock when called with interrupts disabled */ | |
362 | WARN_ON(irqs_disabled()); | |
363 | ||
54b11e6d RR |
364 | /* So, what's a CPU they want? Ignoring this one. */ |
365 | cpu = cpumask_first_and(mask, cpu_online_mask); | |
8969a5ed | 366 | if (cpu == me) |
54b11e6d RR |
367 | cpu = cpumask_next_and(cpu, mask, cpu_online_mask); |
368 | /* No online cpus? We're done. */ | |
369 | if (cpu >= nr_cpu_ids) | |
370 | return; | |
371 | ||
372 | /* Do we have another CPU which isn't us? */ | |
373 | next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask); | |
8969a5ed | 374 | if (next_cpu == me) |
54b11e6d RR |
375 | next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask); |
376 | ||
377 | /* Fastpath: do that cpu by itself. */ | |
378 | if (next_cpu >= nr_cpu_ids) { | |
379 | smp_call_function_single(cpu, func, info, wait); | |
380 | return; | |
3d442233 JA |
381 | } |
382 | ||
8969a5ed PZ |
383 | data = &__get_cpu_var(cfd_data); |
384 | csd_lock(&data->csd); | |
3d442233 | 385 | |
8969a5ed | 386 | spin_lock_irqsave(&data->lock, flags); |
3d442233 JA |
387 | data->csd.func = func; |
388 | data->csd.info = info; | |
8969a5ed PZ |
389 | cpumask_and(data->cpumask, mask, cpu_online_mask); |
390 | cpumask_clear_cpu(me, data->cpumask); | |
391 | data->refs = cpumask_weight(data->cpumask); | |
3d442233 | 392 | |
8969a5ed PZ |
393 | spin_lock(&call_function.lock); |
394 | /* | |
395 | * Place entry at the _HEAD_ of the list, so that any cpu still | |
396 | * observing the entry in generic_smp_call_function_interrupt() will | |
397 | * not miss any other list entries. | |
398 | */ | |
399 | list_add_rcu(&data->csd.list, &call_function.queue); | |
400 | spin_unlock(&call_function.lock); | |
401 | spin_unlock_irqrestore(&data->lock, flags); | |
3d442233 | 402 | |
561920a0 SS |
403 | /* |
404 | * Make the list addition visible before sending the ipi. | |
15d0d3b3 NP |
405 | * (IPIs must obey or appear to obey normal Linux cache coherency |
406 | * rules -- see comment in generic_exec_single). | |
561920a0 SS |
407 | */ |
408 | smp_mb(); | |
409 | ||
3d442233 | 410 | /* Send a message to all CPUs in the map */ |
8969a5ed | 411 | arch_send_call_function_ipi_mask(data->cpumask); |
3d442233 JA |
412 | |
413 | /* optionally wait for the CPUs to complete */ | |
54b11e6d | 414 | if (wait) |
6e275637 | 415 | csd_lock_wait(&data->csd); |
3d442233 | 416 | } |
54b11e6d | 417 | EXPORT_SYMBOL(smp_call_function_many); |
3d442233 JA |
418 | |
419 | /** | |
420 | * smp_call_function(): Run a function on all other CPUs. | |
421 | * @func: The function to run. This must be fast and non-blocking. | |
422 | * @info: An arbitrary pointer to pass to the function. | |
3d442233 JA |
423 | * @wait: If true, wait (atomically) until function has completed on other CPUs. |
424 | * | |
54b11e6d | 425 | * Returns 0. |
3d442233 JA |
426 | * |
427 | * If @wait is true, then returns once @func has returned; otherwise | |
428 | * it returns just before the target cpu calls @func. In case of allocation | |
429 | * failure, @wait will be implicitly turned on. | |
430 | * | |
431 | * You must not call this function with disabled interrupts or from a | |
432 | * hardware interrupt handler or from a bottom half handler. | |
433 | */ | |
8691e5a8 | 434 | int smp_call_function(void (*func)(void *), void *info, int wait) |
3d442233 | 435 | { |
3d442233 | 436 | preempt_disable(); |
54b11e6d | 437 | smp_call_function_many(cpu_online_mask, func, info, wait); |
3d442233 | 438 | preempt_enable(); |
54b11e6d | 439 | return 0; |
3d442233 JA |
440 | } |
441 | EXPORT_SYMBOL(smp_call_function); | |
442 | ||
443 | void ipi_call_lock(void) | |
444 | { | |
8969a5ed | 445 | spin_lock(&call_function.lock); |
3d442233 JA |
446 | } |
447 | ||
448 | void ipi_call_unlock(void) | |
449 | { | |
8969a5ed | 450 | spin_unlock(&call_function.lock); |
3d442233 JA |
451 | } |
452 | ||
453 | void ipi_call_lock_irq(void) | |
454 | { | |
8969a5ed | 455 | spin_lock_irq(&call_function.lock); |
3d442233 JA |
456 | } |
457 | ||
458 | void ipi_call_unlock_irq(void) | |
459 | { | |
8969a5ed | 460 | spin_unlock_irq(&call_function.lock); |
3d442233 | 461 | } |