1 | // SPDX-License-Identifier: GPL-2.0-only |
---|---|
2 | /* |
3 | * Generic helpers for smp ipi calls |
4 | * |
5 | * (C) Jens Axboe <jens.axboe@oracle.com> 2008 |
6 | */ |
7 | |
8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
9 | |
10 | #include <linux/irq_work.h> |
11 | #include <linux/rcupdate.h> |
12 | #include <linux/rculist.h> |
13 | #include <linux/kernel.h> |
14 | #include <linux/export.h> |
15 | #include <linux/percpu.h> |
16 | #include <linux/init.h> |
17 | #include <linux/interrupt.h> |
18 | #include <linux/gfp.h> |
19 | #include <linux/smp.h> |
20 | #include <linux/cpu.h> |
21 | #include <linux/sched.h> |
22 | #include <linux/sched/idle.h> |
23 | #include <linux/hypervisor.h> |
24 | #include <linux/sched/clock.h> |
25 | #include <linux/nmi.h> |
26 | #include <linux/sched/debug.h> |
27 | #include <linux/jump_label.h> |
28 | #include <linux/string_choices.h> |
29 | |
30 | #include <trace/events/ipi.h> |
31 | #define CREATE_TRACE_POINTS |
32 | #include <trace/events/csd.h> |
33 | #undef CREATE_TRACE_POINTS |
34 | |
35 | #include "smpboot.h" |
36 | #include "sched/smp.h" |
37 | |
38 | #define CSD_TYPE(_csd) ((_csd)->node.u_flags & CSD_FLAG_TYPE_MASK) |
39 | |
40 | struct call_function_data { |
41 | call_single_data_t __percpu *csd; |
42 | cpumask_var_t cpumask; |
43 | cpumask_var_t cpumask_ipi; |
44 | }; |
45 | |
46 | static DEFINE_PER_CPU_ALIGNED(struct call_function_data, cfd_data); |
47 | |
48 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue); |
49 | |
50 | static DEFINE_PER_CPU(atomic_t, trigger_backtrace) = ATOMIC_INIT(1); |
51 | |
52 | static void __flush_smp_call_function_queue(bool warn_cpu_offline); |
53 | |
54 | int smpcfd_prepare_cpu(unsigned int cpu) |
55 | { |
56 | struct call_function_data *cfd = &per_cpu(cfd_data, cpu); |
57 | |
58 | if (!zalloc_cpumask_var_node(mask: &cfd->cpumask, GFP_KERNEL, |
59 | cpu_to_node(cpu))) |
60 | return -ENOMEM; |
61 | if (!zalloc_cpumask_var_node(mask: &cfd->cpumask_ipi, GFP_KERNEL, |
62 | cpu_to_node(cpu))) { |
63 | free_cpumask_var(mask: cfd->cpumask); |
64 | return -ENOMEM; |
65 | } |
66 | cfd->csd = alloc_percpu(call_single_data_t); |
67 | if (!cfd->csd) { |
68 | free_cpumask_var(mask: cfd->cpumask); |
69 | free_cpumask_var(mask: cfd->cpumask_ipi); |
70 | return -ENOMEM; |
71 | } |
72 | |
73 | return 0; |
74 | } |
75 | |
76 | int smpcfd_dead_cpu(unsigned int cpu) |
77 | { |
78 | struct call_function_data *cfd = &per_cpu(cfd_data, cpu); |
79 | |
80 | free_cpumask_var(mask: cfd->cpumask); |
81 | free_cpumask_var(mask: cfd->cpumask_ipi); |
82 | free_percpu(pdata: cfd->csd); |
83 | return 0; |
84 | } |
85 | |
86 | int smpcfd_dying_cpu(unsigned int cpu) |
87 | { |
88 | /* |
89 | * The IPIs for the smp-call-function callbacks queued by other |
90 | * CPUs might arrive late, either due to hardware latencies or |
91 | * because this CPU disabled interrupts (inside stop-machine) |
92 | * before the IPIs were sent. So flush out any pending callbacks |
93 | * explicitly (without waiting for the IPIs to arrive), to |
94 | * ensure that the outgoing CPU doesn't go offline with work |
95 | * still pending. |
96 | */ |
97 | __flush_smp_call_function_queue(warn_cpu_offline: false); |
98 | irq_work_run(); |
99 | return 0; |
100 | } |
101 | |
102 | void __init call_function_init(void) |
103 | { |
104 | int i; |
105 | |
106 | for_each_possible_cpu(i) |
107 | init_llist_head(list: &per_cpu(call_single_queue, i)); |
108 | |
109 | smpcfd_prepare_cpu(smp_processor_id()); |
110 | } |
111 | |
112 | static __always_inline void |
113 | send_call_function_single_ipi(int cpu) |
114 | { |
115 | if (call_function_single_prep_ipi(cpu)) { |
116 | trace_ipi_send_cpu(cpu, _RET_IP_, |
117 | callback: generic_smp_call_function_single_interrupt); |
118 | arch_send_call_function_single_ipi(cpu); |
119 | } |
120 | } |
121 | |
122 | static __always_inline void |
123 | send_call_function_ipi_mask(struct cpumask *mask) |
124 | { |
125 | trace_ipi_send_cpumask(cpumask: mask, _RET_IP_, |
126 | callback: generic_smp_call_function_single_interrupt); |
127 | arch_send_call_function_ipi_mask(mask); |
128 | } |
129 | |
130 | static __always_inline void |
131 | csd_do_func(smp_call_func_t func, void *info, call_single_data_t *csd) |
132 | { |
133 | trace_csd_function_entry(func, csd); |
134 | func(info); |
135 | trace_csd_function_exit(func, csd); |
136 | } |
137 | |
138 | #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG |
139 | |
140 | static DEFINE_STATIC_KEY_MAYBE(CONFIG_CSD_LOCK_WAIT_DEBUG_DEFAULT, csdlock_debug_enabled); |
141 | |
142 | /* |
143 | * Parse the csdlock_debug= kernel boot parameter. |
144 | * |
145 | * If you need to restore the old "ext" value that once provided |
146 | * additional debugging information, reapply the following commits: |
147 | * |
148 | * de7b09ef658d ("locking/csd_lock: Prepare more CSD lock debugging") |
149 | * a5aabace5fb8 ("locking/csd_lock: Add more data to CSD lock debugging") |
150 | */ |
151 | static int __init csdlock_debug(char *str) |
152 | { |
153 | int ret; |
154 | unsigned int val = 0; |
155 | |
156 | ret = get_option(str: &str, pint: &val); |
157 | if (ret) { |
158 | if (val) |
159 | static_branch_enable(&csdlock_debug_enabled); |
160 | else |
161 | static_branch_disable(&csdlock_debug_enabled); |
162 | } |
163 | |
164 | return 1; |
165 | } |
166 | __setup("csdlock_debug=", csdlock_debug); |
167 | |
168 | static DEFINE_PER_CPU(call_single_data_t *, cur_csd); |
169 | static DEFINE_PER_CPU(smp_call_func_t, cur_csd_func); |
170 | static DEFINE_PER_CPU(void *, cur_csd_info); |
171 | |
172 | static ulong csd_lock_timeout = 5000; /* CSD lock timeout in milliseconds. */ |
173 | module_param(csd_lock_timeout, ulong, 0644); |
174 | static int panic_on_ipistall; /* CSD panic timeout in milliseconds, 300000 for five minutes. */ |
175 | module_param(panic_on_ipistall, int, 0644); |
176 | |
177 | static atomic_t csd_bug_count = ATOMIC_INIT(0); |
178 | |
179 | /* Record current CSD work for current CPU, NULL to erase. */ |
180 | static void __csd_lock_record(call_single_data_t *csd) |
181 | { |
182 | if (!csd) { |
183 | smp_mb(); /* NULL cur_csd after unlock. */ |
184 | __this_cpu_write(cur_csd, NULL); |
185 | return; |
186 | } |
187 | __this_cpu_write(cur_csd_func, csd->func); |
188 | __this_cpu_write(cur_csd_info, csd->info); |
189 | smp_wmb(); /* func and info before csd. */ |
190 | __this_cpu_write(cur_csd, csd); |
191 | smp_mb(); /* Update cur_csd before function call. */ |
192 | /* Or before unlock, as the case may be. */ |
193 | } |
194 | |
195 | static __always_inline void csd_lock_record(call_single_data_t *csd) |
196 | { |
197 | if (static_branch_unlikely(&csdlock_debug_enabled)) |
198 | __csd_lock_record(csd); |
199 | } |
200 | |
201 | static int csd_lock_wait_getcpu(call_single_data_t *csd) |
202 | { |
203 | unsigned int csd_type; |
204 | |
205 | csd_type = CSD_TYPE(csd); |
206 | if (csd_type == CSD_TYPE_ASYNC || csd_type == CSD_TYPE_SYNC) |
207 | return csd->node.dst; /* Other CSD_TYPE_ values might not have ->dst. */ |
208 | return -1; |
209 | } |
210 | |
211 | static atomic_t n_csd_lock_stuck; |
212 | |
213 | /** |
214 | * csd_lock_is_stuck - Has a CSD-lock acquisition been stuck too long? |
215 | * |
216 | * Returns @true if a CSD-lock acquisition is stuck and has been stuck |
217 | * long enough for a "non-responsive CSD lock" message to be printed. |
218 | */ |
219 | bool csd_lock_is_stuck(void) |
220 | { |
221 | return !!atomic_read(v: &n_csd_lock_stuck); |
222 | } |
223 | |
224 | /* |
225 | * Complain if too much time spent waiting. Note that only |
226 | * the CSD_TYPE_SYNC/ASYNC types provide the destination CPU, |
227 | * so waiting on other types gets much less information. |
228 | */ |
229 | static bool csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, int *bug_id, unsigned long *nmessages) |
230 | { |
231 | int cpu = -1; |
232 | int cpux; |
233 | bool firsttime; |
234 | u64 ts2, ts_delta; |
235 | call_single_data_t *cpu_cur_csd; |
236 | unsigned int flags = READ_ONCE(csd->node.u_flags); |
237 | unsigned long long csd_lock_timeout_ns = csd_lock_timeout * NSEC_PER_MSEC; |
238 | |
239 | if (!(flags & CSD_FLAG_LOCK)) { |
240 | if (!unlikely(*bug_id)) |
241 | return true; |
242 | cpu = csd_lock_wait_getcpu(csd); |
243 | pr_alert("csd: CSD lock (#%d) got unstuck on CPU#%02d, CPU#%02d released the lock.\n", |
244 | *bug_id, raw_smp_processor_id(), cpu); |
245 | atomic_dec(v: &n_csd_lock_stuck); |
246 | return true; |
247 | } |
248 | |
249 | ts2 = ktime_get_mono_fast_ns(); |
250 | /* How long since we last checked for a stuck CSD lock.*/ |
251 | ts_delta = ts2 - *ts1; |
252 | if (likely(ts_delta <= csd_lock_timeout_ns * (*nmessages + 1) * |
253 | (!*nmessages ? 1 : (ilog2(num_online_cpus()) / 2 + 1)) || |
254 | csd_lock_timeout_ns == 0)) |
255 | return false; |
256 | |
257 | if (ts0 > ts2) { |
258 | /* Our own sched_clock went backward; don't blame another CPU. */ |
259 | ts_delta = ts0 - ts2; |
260 | pr_alert("sched_clock on CPU %d went backward by %llu ns\n", raw_smp_processor_id(), ts_delta); |
261 | *ts1 = ts2; |
262 | return false; |
263 | } |
264 | |
265 | firsttime = !*bug_id; |
266 | if (firsttime) |
267 | *bug_id = atomic_inc_return(v: &csd_bug_count); |
268 | cpu = csd_lock_wait_getcpu(csd); |
269 | if (WARN_ONCE(cpu < 0 || cpu >= nr_cpu_ids, "%s: cpu = %d\n", __func__, cpu)) |
270 | cpux = 0; |
271 | else |
272 | cpux = cpu; |
273 | cpu_cur_csd = smp_load_acquire(&per_cpu(cur_csd, cpux)); /* Before func and info. */ |
274 | /* How long since this CSD lock was stuck. */ |
275 | ts_delta = ts2 - ts0; |
276 | pr_alert("csd: %s non-responsive CSD lock (#%d) on CPU#%d, waiting %lld ns for CPU#%02d %pS(%ps).\n", |
277 | firsttime ? "Detected": "Continued", *bug_id, raw_smp_processor_id(), (s64)ts_delta, |
278 | cpu, csd->func, csd->info); |
279 | (*nmessages)++; |
280 | if (firsttime) |
281 | atomic_inc(v: &n_csd_lock_stuck); |
282 | /* |
283 | * If the CSD lock is still stuck after 5 minutes, it is unlikely |
284 | * to become unstuck. Use a signed comparison to avoid triggering |
285 | * on underflows when the TSC is out of sync between sockets. |
286 | */ |
287 | BUG_ON(panic_on_ipistall > 0 && (s64)ts_delta > ((s64)panic_on_ipistall * NSEC_PER_MSEC)); |
288 | if (cpu_cur_csd && csd != cpu_cur_csd) { |
289 | pr_alert("\tcsd: CSD lock (#%d) handling prior %pS(%ps) request.\n", |
290 | *bug_id, READ_ONCE(per_cpu(cur_csd_func, cpux)), |
291 | READ_ONCE(per_cpu(cur_csd_info, cpux))); |
292 | } else { |
293 | pr_alert("\tcsd: CSD lock (#%d) %s.\n", |
294 | *bug_id, !cpu_cur_csd ? "unresponsive": "handling this request"); |
295 | } |
296 | if (cpu >= 0) { |
297 | if (atomic_cmpxchg_acquire(v: &per_cpu(trigger_backtrace, cpu), old: 1, new: 0)) |
298 | dump_cpu_task(cpu); |
299 | if (!cpu_cur_csd) { |
300 | pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id, raw_smp_processor_id(), cpu); |
301 | arch_send_call_function_single_ipi(cpu); |
302 | } |
303 | } |
304 | if (firsttime) |
305 | dump_stack(); |
306 | *ts1 = ts2; |
307 | |
308 | return false; |
309 | } |
310 | |
311 | /* |
312 | * csd_lock/csd_unlock used to serialize access to per-cpu csd resources |
313 | * |
314 | * For non-synchronous ipi calls the csd can still be in use by the |
315 | * previous function call. For multi-cpu calls its even more interesting |
316 | * as we'll have to ensure no other cpu is observing our csd. |
317 | */ |
318 | static void __csd_lock_wait(call_single_data_t *csd) |
319 | { |
320 | unsigned long nmessages = 0; |
321 | int bug_id = 0; |
322 | u64 ts0, ts1; |
323 | |
324 | ts1 = ts0 = ktime_get_mono_fast_ns(); |
325 | for (;;) { |
326 | if (csd_lock_wait_toolong(csd, ts0, ts1: &ts1, bug_id: &bug_id, nmessages: &nmessages)) |
327 | break; |
328 | cpu_relax(); |
329 | } |
330 | smp_acquire__after_ctrl_dep(); |
331 | } |
332 | |
333 | static __always_inline void csd_lock_wait(call_single_data_t *csd) |
334 | { |
335 | if (static_branch_unlikely(&csdlock_debug_enabled)) { |
336 | __csd_lock_wait(csd); |
337 | return; |
338 | } |
339 | |
340 | smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK)); |
341 | } |
342 | #else |
343 | static void csd_lock_record(call_single_data_t *csd) |
344 | { |
345 | } |
346 | |
347 | static __always_inline void csd_lock_wait(call_single_data_t *csd) |
348 | { |
349 | smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK)); |
350 | } |
351 | #endif |
352 | |
353 | static __always_inline void csd_lock(call_single_data_t *csd) |
354 | { |
355 | csd_lock_wait(csd); |
356 | csd->node.u_flags |= CSD_FLAG_LOCK; |
357 | |
358 | /* |
359 | * prevent CPU from reordering the above assignment |
360 | * to ->flags with any subsequent assignments to other |
361 | * fields of the specified call_single_data_t structure: |
362 | */ |
363 | smp_wmb(); |
364 | } |
365 | |
366 | static __always_inline void csd_unlock(call_single_data_t *csd) |
367 | { |
368 | WARN_ON(!(csd->node.u_flags & CSD_FLAG_LOCK)); |
369 | |
370 | /* |
371 | * ensure we're all done before releasing data: |
372 | */ |
373 | smp_store_release(&csd->node.u_flags, 0); |
374 | } |
375 | |
376 | static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data); |
377 | |
378 | void __smp_call_single_queue(int cpu, struct llist_node *node) |
379 | { |
380 | /* |
381 | * We have to check the type of the CSD before queueing it, because |
382 | * once queued it can have its flags cleared by |
383 | * flush_smp_call_function_queue() |
384 | * even if we haven't sent the smp_call IPI yet (e.g. the stopper |
385 | * executes migration_cpu_stop() on the remote CPU). |
386 | */ |
387 | if (trace_csd_queue_cpu_enabled()) { |
388 | call_single_data_t *csd; |
389 | smp_call_func_t func; |
390 | |
391 | csd = container_of(node, call_single_data_t, node.llist); |
392 | func = CSD_TYPE(csd) == CSD_TYPE_TTWU ? |
393 | sched_ttwu_pending : csd->func; |
394 | |
395 | trace_csd_queue_cpu(cpu, _RET_IP_, func, csd); |
396 | } |
397 | |
398 | /* |
399 | * The list addition should be visible to the target CPU when it pops |
400 | * the head of the list to pull the entry off it in the IPI handler |
401 | * because of normal cache coherency rules implied by the underlying |
402 | * llist ops. |
403 | * |
404 | * If IPIs can go out of order to the cache coherency protocol |
405 | * in an architecture, sufficient synchronisation should be added |
406 | * to arch code to make it appear to obey cache coherency WRT |
407 | * locking and barrier primitives. Generic code isn't really |
408 | * equipped to do the right thing... |
409 | */ |
410 | if (llist_add(new: node, head: &per_cpu(call_single_queue, cpu))) |
411 | send_call_function_single_ipi(cpu); |
412 | } |
413 | |
414 | /* |
415 | * Insert a previously allocated call_single_data_t element |
416 | * for execution on the given CPU. data must already have |
417 | * ->func, ->info, and ->flags set. |
418 | */ |
419 | static int generic_exec_single(int cpu, call_single_data_t *csd) |
420 | { |
421 | if (cpu == smp_processor_id()) { |
422 | smp_call_func_t func = csd->func; |
423 | void *info = csd->info; |
424 | unsigned long flags; |
425 | |
426 | /* |
427 | * We can unlock early even for the synchronous on-stack case, |
428 | * since we're doing this from the same CPU.. |
429 | */ |
430 | csd_lock_record(csd); |
431 | csd_unlock(csd); |
432 | local_irq_save(flags); |
433 | csd_do_func(func, info, NULL); |
434 | csd_lock_record(NULL); |
435 | local_irq_restore(flags); |
436 | return 0; |
437 | } |
438 | |
439 | if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) { |
440 | csd_unlock(csd); |
441 | return -ENXIO; |
442 | } |
443 | |
444 | __smp_call_single_queue(cpu, node: &csd->node.llist); |
445 | |
446 | return 0; |
447 | } |
448 | |
449 | /** |
450 | * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks |
451 | * |
452 | * Invoked by arch to handle an IPI for call function single. |
453 | * Must be called with interrupts disabled. |
454 | */ |
455 | void generic_smp_call_function_single_interrupt(void) |
456 | { |
457 | __flush_smp_call_function_queue(warn_cpu_offline: true); |
458 | } |
459 | |
460 | /** |
461 | * __flush_smp_call_function_queue - Flush pending smp-call-function callbacks |
462 | * |
463 | * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an |
464 | * offline CPU. Skip this check if set to 'false'. |
465 | * |
466 | * Flush any pending smp-call-function callbacks queued on this CPU. This is |
467 | * invoked by the generic IPI handler, as well as by a CPU about to go offline, |
468 | * to ensure that all pending IPI callbacks are run before it goes completely |
469 | * offline. |
470 | * |
471 | * Loop through the call_single_queue and run all the queued callbacks. |
472 | * Must be called with interrupts disabled. |
473 | */ |
474 | static void __flush_smp_call_function_queue(bool warn_cpu_offline) |
475 | { |
476 | call_single_data_t *csd, *csd_next; |
477 | struct llist_node *entry, *prev; |
478 | struct llist_head *head; |
479 | static bool warned; |
480 | atomic_t *tbt; |
481 | |
482 | lockdep_assert_irqs_disabled(); |
483 | |
484 | /* Allow waiters to send backtrace NMI from here onwards */ |
485 | tbt = this_cpu_ptr(&trigger_backtrace); |
486 | atomic_set_release(v: tbt, i: 1); |
487 | |
488 | head = this_cpu_ptr(&call_single_queue); |
489 | entry = llist_del_all(head); |
490 | entry = llist_reverse_order(head: entry); |
491 | |
492 | /* There shouldn't be any pending callbacks on an offline CPU. */ |
493 | if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) && |
494 | !warned && entry != NULL)) { |
495 | warned = true; |
496 | WARN(1, "IPI on offline CPU %d\n", smp_processor_id()); |
497 | |
498 | /* |
499 | * We don't have to use the _safe() variant here |
500 | * because we are not invoking the IPI handlers yet. |
501 | */ |
502 | llist_for_each_entry(csd, entry, node.llist) { |
503 | switch (CSD_TYPE(csd)) { |
504 | case CSD_TYPE_ASYNC: |
505 | case CSD_TYPE_SYNC: |
506 | case CSD_TYPE_IRQ_WORK: |
507 | pr_warn("IPI callback %pS sent to offline CPU\n", |
508 | csd->func); |
509 | break; |
510 | |
511 | case CSD_TYPE_TTWU: |
512 | pr_warn("IPI task-wakeup sent to offline CPU\n"); |
513 | break; |
514 | |
515 | default: |
516 | pr_warn("IPI callback, unknown type %d, sent to offline CPU\n", |
517 | CSD_TYPE(csd)); |
518 | break; |
519 | } |
520 | } |
521 | } |
522 | |
523 | /* |
524 | * First; run all SYNC callbacks, people are waiting for us. |
525 | */ |
526 | prev = NULL; |
527 | llist_for_each_entry_safe(csd, csd_next, entry, node.llist) { |
528 | /* Do we wait until *after* callback? */ |
529 | if (CSD_TYPE(csd) == CSD_TYPE_SYNC) { |
530 | smp_call_func_t func = csd->func; |
531 | void *info = csd->info; |
532 | |
533 | if (prev) { |
534 | prev->next = &csd_next->node.llist; |
535 | } else { |
536 | entry = &csd_next->node.llist; |
537 | } |
538 | |
539 | csd_lock_record(csd); |
540 | csd_do_func(func, info, csd); |
541 | csd_unlock(csd); |
542 | csd_lock_record(NULL); |
543 | } else { |
544 | prev = &csd->node.llist; |
545 | } |
546 | } |
547 | |
548 | if (!entry) |
549 | return; |
550 | |
551 | /* |
552 | * Second; run all !SYNC callbacks. |
553 | */ |
554 | prev = NULL; |
555 | llist_for_each_entry_safe(csd, csd_next, entry, node.llist) { |
556 | int type = CSD_TYPE(csd); |
557 | |
558 | if (type != CSD_TYPE_TTWU) { |
559 | if (prev) { |
560 | prev->next = &csd_next->node.llist; |
561 | } else { |
562 | entry = &csd_next->node.llist; |
563 | } |
564 | |
565 | if (type == CSD_TYPE_ASYNC) { |
566 | smp_call_func_t func = csd->func; |
567 | void *info = csd->info; |
568 | |
569 | csd_lock_record(csd); |
570 | csd_unlock(csd); |
571 | csd_do_func(func, info, csd); |
572 | csd_lock_record(NULL); |
573 | } else if (type == CSD_TYPE_IRQ_WORK) { |
574 | irq_work_single(arg: csd); |
575 | } |
576 | |
577 | } else { |
578 | prev = &csd->node.llist; |
579 | } |
580 | } |
581 | |
582 | /* |
583 | * Third; only CSD_TYPE_TTWU is left, issue those. |
584 | */ |
585 | if (entry) { |
586 | csd = llist_entry(entry, typeof(*csd), node.llist); |
587 | csd_do_func(func: sched_ttwu_pending, info: entry, csd); |
588 | } |
589 | } |
590 | |
591 | |
592 | /** |
593 | * flush_smp_call_function_queue - Flush pending smp-call-function callbacks |
594 | * from task context (idle, migration thread) |
595 | * |
596 | * When TIF_POLLING_NRFLAG is supported and a CPU is in idle and has it |
597 | * set, then remote CPUs can avoid sending IPIs and wake the idle CPU by |
598 | * setting TIF_NEED_RESCHED. The idle task on the woken up CPU has to |
599 | * handle queued SMP function calls before scheduling. |
600 | * |
601 | * The migration thread has to ensure that an eventually pending wakeup has |
602 | * been handled before it migrates a task. |
603 | */ |
604 | void flush_smp_call_function_queue(void) |
605 | { |
606 | unsigned int was_pending; |
607 | unsigned long flags; |
608 | |
609 | if (llist_empty(this_cpu_ptr(&call_single_queue))) |
610 | return; |
611 | |
612 | local_irq_save(flags); |
613 | /* Get the already pending soft interrupts for RT enabled kernels */ |
614 | was_pending = local_softirq_pending(); |
615 | __flush_smp_call_function_queue(warn_cpu_offline: true); |
616 | if (local_softirq_pending()) |
617 | do_softirq_post_smp_call_flush(unused: was_pending); |
618 | |
619 | local_irq_restore(flags); |
620 | } |
621 | |
622 | /* |
623 | * smp_call_function_single - Run a function on a specific CPU |
624 | * @func: The function to run. This must be fast and non-blocking. |
625 | * @info: An arbitrary pointer to pass to the function. |
626 | * @wait: If true, wait until function has completed on other CPUs. |
627 | * |
628 | * Returns 0 on success, else a negative status code. |
629 | */ |
630 | int smp_call_function_single(int cpu, smp_call_func_t func, void *info, |
631 | int wait) |
632 | { |
633 | call_single_data_t *csd; |
634 | call_single_data_t csd_stack = { |
635 | .node = { .u_flags = CSD_FLAG_LOCK | CSD_TYPE_SYNC, }, |
636 | }; |
637 | int this_cpu; |
638 | int err; |
639 | |
640 | /* |
641 | * prevent preemption and reschedule on another processor, |
642 | * as well as CPU removal |
643 | */ |
644 | this_cpu = get_cpu(); |
645 | |
646 | /* |
647 | * Can deadlock when called with interrupts disabled. |
648 | * We allow cpu's that are not yet online though, as no one else can |
649 | * send smp call function interrupt to this cpu and as such deadlocks |
650 | * can't happen. |
651 | */ |
652 | WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() |
653 | && !oops_in_progress); |
654 | |
655 | /* |
656 | * When @wait we can deadlock when we interrupt between llist_add() and |
657 | * arch_send_call_function_ipi*(); when !@wait we can deadlock due to |
658 | * csd_lock() on because the interrupt context uses the same csd |
659 | * storage. |
660 | */ |
661 | WARN_ON_ONCE(!in_task()); |
662 | |
663 | csd = &csd_stack; |
664 | if (!wait) { |
665 | csd = this_cpu_ptr(&csd_data); |
666 | csd_lock(csd); |
667 | } |
668 | |
669 | csd->func = func; |
670 | csd->info = info; |
671 | #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG |
672 | csd->node.src = smp_processor_id(); |
673 | csd->node.dst = cpu; |
674 | #endif |
675 | |
676 | err = generic_exec_single(cpu, csd); |
677 | |
678 | if (wait) |
679 | csd_lock_wait(csd); |
680 | |
681 | put_cpu(); |
682 | |
683 | return err; |
684 | } |
685 | EXPORT_SYMBOL(smp_call_function_single); |
686 | |
687 | /** |
688 | * smp_call_function_single_async() - Run an asynchronous function on a |
689 | * specific CPU. |
690 | * @cpu: The CPU to run on. |
691 | * @csd: Pre-allocated and setup data structure |
692 | * |
693 | * Like smp_call_function_single(), but the call is asynchonous and |
694 | * can thus be done from contexts with disabled interrupts. |
695 | * |
696 | * The caller passes his own pre-allocated data structure |
697 | * (ie: embedded in an object) and is responsible for synchronizing it |
698 | * such that the IPIs performed on the @csd are strictly serialized. |
699 | * |
700 | * If the function is called with one csd which has not yet been |
701 | * processed by previous call to smp_call_function_single_async(), the |
702 | * function will return immediately with -EBUSY showing that the csd |
703 | * object is still in progress. |
704 | * |
705 | * NOTE: Be careful, there is unfortunately no current debugging facility to |
706 | * validate the correctness of this serialization. |
707 | * |
708 | * Return: %0 on success or negative errno value on error |
709 | */ |
710 | int smp_call_function_single_async(int cpu, call_single_data_t *csd) |
711 | { |
712 | int err = 0; |
713 | |
714 | preempt_disable(); |
715 | |
716 | if (csd->node.u_flags & CSD_FLAG_LOCK) { |
717 | err = -EBUSY; |
718 | goto out; |
719 | } |
720 | |
721 | csd->node.u_flags = CSD_FLAG_LOCK; |
722 | smp_wmb(); |
723 | |
724 | err = generic_exec_single(cpu, csd); |
725 | |
726 | out: |
727 | preempt_enable(); |
728 | |
729 | return err; |
730 | } |
731 | EXPORT_SYMBOL_GPL(smp_call_function_single_async); |
732 | |
733 | /* |
734 | * smp_call_function_any - Run a function on any of the given cpus |
735 | * @mask: The mask of cpus it can run on. |
736 | * @func: The function to run. This must be fast and non-blocking. |
737 | * @info: An arbitrary pointer to pass to the function. |
738 | * @wait: If true, wait until function has completed. |
739 | * |
740 | * Returns 0 on success, else a negative status code (if no cpus were online). |
741 | * |
742 | * Selection preference: |
743 | * 1) current cpu if in @mask |
744 | * 2) any cpu of current node if in @mask |
745 | * 3) any other online cpu in @mask |
746 | */ |
747 | int smp_call_function_any(const struct cpumask *mask, |
748 | smp_call_func_t func, void *info, int wait) |
749 | { |
750 | unsigned int cpu; |
751 | const struct cpumask *nodemask; |
752 | int ret; |
753 | |
754 | /* Try for same CPU (cheapest) */ |
755 | cpu = get_cpu(); |
756 | if (cpumask_test_cpu(cpu, cpumask: mask)) |
757 | goto call; |
758 | |
759 | /* Try for same node. */ |
760 | nodemask = cpumask_of_node(cpu_to_node(cpu)); |
761 | for (cpu = cpumask_first_and(srcp1: nodemask, srcp2: mask); cpu < nr_cpu_ids; |
762 | cpu = cpumask_next_and(n: cpu, src1p: nodemask, src2p: mask)) { |
763 | if (cpu_online(cpu)) |
764 | goto call; |
765 | } |
766 | |
767 | /* Any online will do: smp_call_function_single handles nr_cpu_ids. */ |
768 | cpu = cpumask_any_and(mask, cpu_online_mask); |
769 | call: |
770 | ret = smp_call_function_single(cpu, func, info, wait); |
771 | put_cpu(); |
772 | return ret; |
773 | } |
774 | EXPORT_SYMBOL_GPL(smp_call_function_any); |
775 | |
776 | /* |
777 | * Flags to be used as scf_flags argument of smp_call_function_many_cond(). |
778 | * |
779 | * %SCF_WAIT: Wait until function execution is completed |
780 | * %SCF_RUN_LOCAL: Run also locally if local cpu is set in cpumask |
781 | */ |
782 | #define SCF_WAIT (1U << 0) |
783 | #define SCF_RUN_LOCAL (1U << 1) |
784 | |
785 | static void smp_call_function_many_cond(const struct cpumask *mask, |
786 | smp_call_func_t func, void *info, |
787 | unsigned int scf_flags, |
788 | smp_cond_func_t cond_func) |
789 | { |
790 | int cpu, last_cpu, this_cpu = smp_processor_id(); |
791 | struct call_function_data *cfd; |
792 | bool wait = scf_flags & SCF_WAIT; |
793 | int nr_cpus = 0; |
794 | bool run_remote = false; |
795 | bool run_local = false; |
796 | |
797 | lockdep_assert_preemption_disabled(); |
798 | |
799 | /* |
800 | * Can deadlock when called with interrupts disabled. |
801 | * We allow cpu's that are not yet online though, as no one else can |
802 | * send smp call function interrupt to this cpu and as such deadlocks |
803 | * can't happen. |
804 | */ |
805 | if (cpu_online(cpu: this_cpu) && !oops_in_progress && |
806 | !early_boot_irqs_disabled) |
807 | lockdep_assert_irqs_enabled(); |
808 | |
809 | /* |
810 | * When @wait we can deadlock when we interrupt between llist_add() and |
811 | * arch_send_call_function_ipi*(); when !@wait we can deadlock due to |
812 | * csd_lock() on because the interrupt context uses the same csd |
813 | * storage. |
814 | */ |
815 | WARN_ON_ONCE(!in_task()); |
816 | |
817 | /* Check if we need local execution. */ |
818 | if ((scf_flags & SCF_RUN_LOCAL) && cpumask_test_cpu(cpu: this_cpu, cpumask: mask) && |
819 | (!cond_func || cond_func(this_cpu, info))) |
820 | run_local = true; |
821 | |
822 | /* Check if we need remote execution, i.e., any CPU excluding this one. */ |
823 | cpu = cpumask_first_and(srcp1: mask, cpu_online_mask); |
824 | if (cpu == this_cpu) |
825 | cpu = cpumask_next_and(n: cpu, src1p: mask, cpu_online_mask); |
826 | if (cpu < nr_cpu_ids) |
827 | run_remote = true; |
828 | |
829 | if (run_remote) { |
830 | cfd = this_cpu_ptr(&cfd_data); |
831 | cpumask_and(dstp: cfd->cpumask, src1p: mask, cpu_online_mask); |
832 | __cpumask_clear_cpu(cpu: this_cpu, dstp: cfd->cpumask); |
833 | |
834 | cpumask_clear(dstp: cfd->cpumask_ipi); |
835 | for_each_cpu(cpu, cfd->cpumask) { |
836 | call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu); |
837 | |
838 | if (cond_func && !cond_func(cpu, info)) { |
839 | __cpumask_clear_cpu(cpu, dstp: cfd->cpumask); |
840 | continue; |
841 | } |
842 | |
843 | csd_lock(csd); |
844 | if (wait) |
845 | csd->node.u_flags |= CSD_TYPE_SYNC; |
846 | csd->func = func; |
847 | csd->info = info; |
848 | #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG |
849 | csd->node.src = smp_processor_id(); |
850 | csd->node.dst = cpu; |
851 | #endif |
852 | trace_csd_queue_cpu(cpu, _RET_IP_, func, csd); |
853 | |
854 | if (llist_add(new: &csd->node.llist, head: &per_cpu(call_single_queue, cpu))) { |
855 | __cpumask_set_cpu(cpu, dstp: cfd->cpumask_ipi); |
856 | nr_cpus++; |
857 | last_cpu = cpu; |
858 | } |
859 | } |
860 | |
861 | /* |
862 | * Choose the most efficient way to send an IPI. Note that the |
863 | * number of CPUs might be zero due to concurrent changes to the |
864 | * provided mask. |
865 | */ |
866 | if (nr_cpus == 1) |
867 | send_call_function_single_ipi(cpu: last_cpu); |
868 | else if (likely(nr_cpus > 1)) |
869 | send_call_function_ipi_mask(mask: cfd->cpumask_ipi); |
870 | } |
871 | |
872 | if (run_local) { |
873 | unsigned long flags; |
874 | |
875 | local_irq_save(flags); |
876 | csd_do_func(func, info, NULL); |
877 | local_irq_restore(flags); |
878 | } |
879 | |
880 | if (run_remote && wait) { |
881 | for_each_cpu(cpu, cfd->cpumask) { |
882 | call_single_data_t *csd; |
883 | |
884 | csd = per_cpu_ptr(cfd->csd, cpu); |
885 | csd_lock_wait(csd); |
886 | } |
887 | } |
888 | } |
889 | |
890 | /** |
891 | * smp_call_function_many(): Run a function on a set of CPUs. |
892 | * @mask: The set of cpus to run on (only runs on online subset). |
893 | * @func: The function to run. This must be fast and non-blocking. |
894 | * @info: An arbitrary pointer to pass to the function. |
895 | * @wait: Bitmask that controls the operation. If %SCF_WAIT is set, wait |
896 | * (atomically) until function has completed on other CPUs. If |
897 | * %SCF_RUN_LOCAL is set, the function will also be run locally |
898 | * if the local CPU is set in the @cpumask. |
899 | * |
900 | * If @wait is true, then returns once @func has returned. |
901 | * |
902 | * You must not call this function with disabled interrupts or from a |
903 | * hardware interrupt handler or from a bottom half handler. Preemption |
904 | * must be disabled when calling this function. |
905 | */ |
906 | void smp_call_function_many(const struct cpumask *mask, |
907 | smp_call_func_t func, void *info, bool wait) |
908 | { |
909 | smp_call_function_many_cond(mask, func, info, scf_flags: wait * SCF_WAIT, NULL); |
910 | } |
911 | EXPORT_SYMBOL(smp_call_function_many); |
912 | |
913 | /** |
914 | * smp_call_function(): Run a function on all other CPUs. |
915 | * @func: The function to run. This must be fast and non-blocking. |
916 | * @info: An arbitrary pointer to pass to the function. |
917 | * @wait: If true, wait (atomically) until function has completed |
918 | * on other CPUs. |
919 | * |
920 | * Returns 0. |
921 | * |
922 | * If @wait is true, then returns once @func has returned; otherwise |
923 | * it returns just before the target cpu calls @func. |
924 | * |
925 | * You must not call this function with disabled interrupts or from a |
926 | * hardware interrupt handler or from a bottom half handler. |
927 | */ |
928 | void smp_call_function(smp_call_func_t func, void *info, int wait) |
929 | { |
930 | preempt_disable(); |
931 | smp_call_function_many(cpu_online_mask, func, info, wait); |
932 | preempt_enable(); |
933 | } |
934 | EXPORT_SYMBOL(smp_call_function); |
935 | |
936 | /* Setup configured maximum number of CPUs to activate */ |
937 | unsigned int setup_max_cpus = NR_CPUS; |
938 | EXPORT_SYMBOL(setup_max_cpus); |
939 | |
940 | |
941 | /* |
942 | * Setup routine for controlling SMP activation |
943 | * |
944 | * Command-line option of "nosmp" or "maxcpus=0" will disable SMP |
945 | * activation entirely (the MPS table probe still happens, though). |
946 | * |
947 | * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer |
948 | * greater than 0, limits the maximum number of CPUs activated in |
949 | * SMP mode to <NUM>. |
950 | */ |
951 | |
952 | void __weak __init arch_disable_smp_support(void) { } |
953 | |
954 | static int __init nosmp(char *str) |
955 | { |
956 | setup_max_cpus = 0; |
957 | arch_disable_smp_support(); |
958 | |
959 | return 0; |
960 | } |
961 | |
962 | early_param("nosmp", nosmp); |
963 | |
964 | /* this is hard limit */ |
965 | static int __init nrcpus(char *str) |
966 | { |
967 | int nr_cpus; |
968 | |
969 | if (get_option(str: &str, pint: &nr_cpus) && nr_cpus > 0 && nr_cpus < nr_cpu_ids) |
970 | set_nr_cpu_ids(nr_cpus); |
971 | |
972 | return 0; |
973 | } |
974 | |
975 | early_param("nr_cpus", nrcpus); |
976 | |
977 | static int __init maxcpus(char *str) |
978 | { |
979 | get_option(str: &str, pint: &setup_max_cpus); |
980 | if (setup_max_cpus == 0) |
981 | arch_disable_smp_support(); |
982 | |
983 | return 0; |
984 | } |
985 | |
986 | early_param("maxcpus", maxcpus); |
987 | |
988 | #if (NR_CPUS > 1) && !defined(CONFIG_FORCE_NR_CPUS) |
989 | /* Setup number of possible processor ids */ |
990 | unsigned int nr_cpu_ids __read_mostly = NR_CPUS; |
991 | EXPORT_SYMBOL(nr_cpu_ids); |
992 | #endif |
993 | |
994 | /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */ |
995 | void __init setup_nr_cpu_ids(void) |
996 | { |
997 | set_nr_cpu_ids(find_last_bit(cpumask_bits(cpu_possible_mask), NR_CPUS) + 1); |
998 | } |
999 | |
1000 | /* Called by boot processor to activate the rest. */ |
1001 | void __init smp_init(void) |
1002 | { |
1003 | int num_nodes, num_cpus; |
1004 | |
1005 | idle_threads_init(); |
1006 | cpuhp_threads_init(); |
1007 | |
1008 | pr_info("Bringing up secondary CPUs ...\n"); |
1009 | |
1010 | bringup_nonboot_cpus(max_cpus: setup_max_cpus); |
1011 | |
1012 | num_nodes = num_online_nodes(); |
1013 | num_cpus = num_online_cpus(); |
1014 | pr_info("Brought up %d node%s, %d CPU%s\n", |
1015 | num_nodes, str_plural(num_nodes), num_cpus, str_plural(num_cpus)); |
1016 | |
1017 | /* Any cleanup work */ |
1018 | smp_cpus_done(max_cpus: setup_max_cpus); |
1019 | } |
1020 | |
1021 | /* |
1022 | * on_each_cpu_cond(): Call a function on each processor for which |
1023 | * the supplied function cond_func returns true, optionally waiting |
1024 | * for all the required CPUs to finish. This may include the local |
1025 | * processor. |
1026 | * @cond_func: A callback function that is passed a cpu id and |
1027 | * the info parameter. The function is called |
1028 | * with preemption disabled. The function should |
1029 | * return a blooean value indicating whether to IPI |
1030 | * the specified CPU. |
1031 | * @func: The function to run on all applicable CPUs. |
1032 | * This must be fast and non-blocking. |
1033 | * @info: An arbitrary pointer to pass to both functions. |
1034 | * @wait: If true, wait (atomically) until function has |
1035 | * completed on other CPUs. |
1036 | * |
1037 | * Preemption is disabled to protect against CPUs going offline but not online. |
1038 | * CPUs going online during the call will not be seen or sent an IPI. |
1039 | * |
1040 | * You must not call this function with disabled interrupts or |
1041 | * from a hardware interrupt handler or from a bottom half handler. |
1042 | */ |
1043 | void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func, |
1044 | void *info, bool wait, const struct cpumask *mask) |
1045 | { |
1046 | unsigned int scf_flags = SCF_RUN_LOCAL; |
1047 | |
1048 | if (wait) |
1049 | scf_flags |= SCF_WAIT; |
1050 | |
1051 | preempt_disable(); |
1052 | smp_call_function_many_cond(mask, func, info, scf_flags, cond_func); |
1053 | preempt_enable(); |
1054 | } |
1055 | EXPORT_SYMBOL(on_each_cpu_cond_mask); |
1056 | |
1057 | static void do_nothing(void *unused) |
1058 | { |
1059 | } |
1060 | |
1061 | /** |
1062 | * kick_all_cpus_sync - Force all cpus out of idle |
1063 | * |
1064 | * Used to synchronize the update of pm_idle function pointer. It's |
1065 | * called after the pointer is updated and returns after the dummy |
1066 | * callback function has been executed on all cpus. The execution of |
1067 | * the function can only happen on the remote cpus after they have |
1068 | * left the idle function which had been called via pm_idle function |
1069 | * pointer. So it's guaranteed that nothing uses the previous pointer |
1070 | * anymore. |
1071 | */ |
1072 | void kick_all_cpus_sync(void) |
1073 | { |
1074 | /* Make sure the change is visible before we kick the cpus */ |
1075 | smp_mb(); |
1076 | smp_call_function(do_nothing, NULL, 1); |
1077 | } |
1078 | EXPORT_SYMBOL_GPL(kick_all_cpus_sync); |
1079 | |
1080 | /** |
1081 | * wake_up_all_idle_cpus - break all cpus out of idle |
1082 | * wake_up_all_idle_cpus try to break all cpus which is in idle state even |
1083 | * including idle polling cpus, for non-idle cpus, we will do nothing |
1084 | * for them. |
1085 | */ |
1086 | void wake_up_all_idle_cpus(void) |
1087 | { |
1088 | int cpu; |
1089 | |
1090 | for_each_possible_cpu(cpu) { |
1091 | preempt_disable(); |
1092 | if (cpu != smp_processor_id() && cpu_online(cpu)) |
1093 | wake_up_if_idle(cpu); |
1094 | preempt_enable(); |
1095 | } |
1096 | } |
1097 | EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus); |
1098 | |
1099 | /** |
1100 | * struct smp_call_on_cpu_struct - Call a function on a specific CPU |
1101 | * @work: &work_struct |
1102 | * @done: &completion to signal |
1103 | * @func: function to call |
1104 | * @data: function's data argument |
1105 | * @ret: return value from @func |
1106 | * @cpu: target CPU (%-1 for any CPU) |
1107 | * |
1108 | * Used to call a function on a specific cpu and wait for it to return. |
1109 | * Optionally make sure the call is done on a specified physical cpu via vcpu |
1110 | * pinning in order to support virtualized environments. |
1111 | */ |
1112 | struct smp_call_on_cpu_struct { |
1113 | struct work_struct work; |
1114 | struct completion done; |
1115 | int (*func)(void *); |
1116 | void *data; |
1117 | int ret; |
1118 | int cpu; |
1119 | }; |
1120 | |
1121 | static void smp_call_on_cpu_callback(struct work_struct *work) |
1122 | { |
1123 | struct smp_call_on_cpu_struct *sscs; |
1124 | |
1125 | sscs = container_of(work, struct smp_call_on_cpu_struct, work); |
1126 | if (sscs->cpu >= 0) |
1127 | hypervisor_pin_vcpu(cpu: sscs->cpu); |
1128 | sscs->ret = sscs->func(sscs->data); |
1129 | if (sscs->cpu >= 0) |
1130 | hypervisor_pin_vcpu(cpu: -1); |
1131 | |
1132 | complete(&sscs->done); |
1133 | } |
1134 | |
1135 | int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys) |
1136 | { |
1137 | struct smp_call_on_cpu_struct sscs = { |
1138 | .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done), |
1139 | .func = func, |
1140 | .data = par, |
1141 | .cpu = phys ? cpu : -1, |
1142 | }; |
1143 | |
1144 | INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback); |
1145 | |
1146 | if (cpu >= nr_cpu_ids || !cpu_online(cpu)) |
1147 | return -ENXIO; |
1148 | |
1149 | queue_work_on(cpu, wq: system_wq, work: &sscs.work); |
1150 | wait_for_completion(&sscs.done); |
1151 | destroy_work_on_stack(work: &sscs.work); |
1152 | |
1153 | return sscs.ret; |
1154 | } |
1155 | EXPORT_SYMBOL_GPL(smp_call_on_cpu); |
1156 |
Definitions
- call_function_data
- cfd_data
- call_single_queue
- trigger_backtrace
- smpcfd_prepare_cpu
- smpcfd_dead_cpu
- smpcfd_dying_cpu
- call_function_init
- send_call_function_single_ipi
- send_call_function_ipi_mask
- csd_do_func
- csdlock_debug_enabled
- csdlock_debug
- cur_csd
- cur_csd_func
- cur_csd_info
- csd_lock_timeout
- panic_on_ipistall
- csd_bug_count
- __csd_lock_record
- csd_lock_record
- csd_lock_wait_getcpu
- n_csd_lock_stuck
- csd_lock_is_stuck
- csd_lock_wait_toolong
- __csd_lock_wait
- csd_lock_wait
- csd_lock
- csd_unlock
- csd_data
- __smp_call_single_queue
- generic_exec_single
- generic_smp_call_function_single_interrupt
- __flush_smp_call_function_queue
- flush_smp_call_function_queue
- smp_call_function_single
- smp_call_function_single_async
- smp_call_function_any
- smp_call_function_many_cond
- smp_call_function_many
- smp_call_function
- setup_max_cpus
- arch_disable_smp_support
- nosmp
- nrcpus
- maxcpus
- nr_cpu_ids
- setup_nr_cpu_ids
- smp_init
- on_each_cpu_cond_mask
- do_nothing
- kick_all_cpus_sync
- wake_up_all_idle_cpus
- smp_call_on_cpu_struct
- smp_call_on_cpu_callback
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