Commit | Line | Data |
---|---|---|
3d442233 JA |
1 | /* |
2 | * Generic helpers for smp ipi calls | |
3 | * | |
4 | * (C) Jens Axboe <jens.axboe@oracle.com> 2008 | |
3d442233 | 5 | */ |
3d442233 | 6 | #include <linux/rcupdate.h> |
59190f42 | 7 | #include <linux/rculist.h> |
0b13fda1 IM |
8 | #include <linux/module.h> |
9 | #include <linux/percpu.h> | |
10 | #include <linux/init.h> | |
3d442233 | 11 | #include <linux/smp.h> |
8969a5ed | 12 | #include <linux/cpu.h> |
3d442233 JA |
13 | |
14 | static DEFINE_PER_CPU(struct call_single_queue, call_single_queue); | |
8969a5ed PZ |
15 | |
16 | static struct { | |
17 | struct list_head queue; | |
18 | spinlock_t lock; | |
0b13fda1 IM |
19 | } call_function __cacheline_aligned_in_smp = |
20 | { | |
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 { | |
0b13fda1 IM |
30 | struct call_single_data csd; |
31 | spinlock_t lock; | |
32 | unsigned int refs; | |
33 | cpumask_var_t cpumask; | |
3d442233 JA |
34 | }; |
35 | ||
36 | struct call_single_queue { | |
0b13fda1 IM |
37 | struct list_head list; |
38 | spinlock_t lock; | |
3d442233 JA |
39 | }; |
40 | ||
8969a5ed | 41 | static DEFINE_PER_CPU(struct call_function_data, cfd_data) = { |
0b13fda1 | 42 | .lock = __SPIN_LOCK_UNLOCKED(cfd_data.lock), |
8969a5ed PZ |
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 = { | |
0b13fda1 | 74 | .notifier_call = hotplug_cfd, |
8969a5ed PZ |
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 | * | |
0b13fda1 IM |
99 | * For non-synchronous ipi calls the csd can still be in use by the |
100 | * previous function call. For multi-cpu calls its even more interesting | |
101 | * as we'll have to ensure no other cpu is observing our csd. | |
8969a5ed | 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 | /* | |
0b13fda1 IM |
115 | * prevent CPU from reordering the above assignment |
116 | * to ->flags with any subsequent assignments to other | |
117 | * fields of the specified call_single_data structure: | |
8969a5ed | 118 | */ |
8969a5ed PZ |
119 | smp_mb(); |
120 | } | |
121 | ||
122 | static void csd_unlock(struct call_single_data *data) | |
123 | { | |
124 | WARN_ON(!(data->flags & CSD_FLAG_LOCK)); | |
0b13fda1 | 125 | |
8969a5ed | 126 | /* |
0b13fda1 | 127 | * ensure we're all done before releasing data: |
8969a5ed PZ |
128 | */ |
129 | smp_mb(); | |
0b13fda1 | 130 | |
8969a5ed | 131 | data->flags &= ~CSD_FLAG_LOCK; |
3d442233 JA |
132 | } |
133 | ||
134 | /* | |
0b13fda1 IM |
135 | * Insert a previously allocated call_single_data element |
136 | * for execution on the given CPU. data must already have | |
137 | * ->func, ->info, and ->flags set. | |
3d442233 | 138 | */ |
6e275637 PZ |
139 | static |
140 | void generic_exec_single(int cpu, struct call_single_data *data, int wait) | |
3d442233 JA |
141 | { |
142 | struct call_single_queue *dst = &per_cpu(call_single_queue, cpu); | |
3d442233 | 143 | unsigned long flags; |
6e275637 | 144 | int ipi; |
3d442233 JA |
145 | |
146 | spin_lock_irqsave(&dst->lock, flags); | |
147 | ipi = list_empty(&dst->list); | |
148 | list_add_tail(&data->list, &dst->list); | |
149 | spin_unlock_irqrestore(&dst->lock, flags); | |
150 | ||
561920a0 | 151 | /* |
15d0d3b3 NP |
152 | * The list addition should be visible before sending the IPI |
153 | * handler locks the list to pull the entry off it because of | |
154 | * normal cache coherency rules implied by spinlocks. | |
155 | * | |
156 | * If IPIs can go out of order to the cache coherency protocol | |
157 | * in an architecture, sufficient synchronisation should be added | |
158 | * to arch code to make it appear to obey cache coherency WRT | |
0b13fda1 IM |
159 | * locking and barrier primitives. Generic code isn't really |
160 | * equipped to do the right thing... | |
561920a0 | 161 | */ |
3d442233 JA |
162 | if (ipi) |
163 | arch_send_call_function_single_ipi(cpu); | |
164 | ||
165 | if (wait) | |
6e275637 | 166 | csd_lock_wait(data); |
3d442233 JA |
167 | } |
168 | ||
169 | /* | |
170 | * Invoked by arch to handle an IPI for call function. Must be called with | |
171 | * interrupts disabled. | |
172 | */ | |
173 | void generic_smp_call_function_interrupt(void) | |
174 | { | |
175 | struct call_function_data *data; | |
176 | int cpu = get_cpu(); | |
177 | ||
15d0d3b3 NP |
178 | /* |
179 | * Ensure entry is visible on call_function_queue after we have | |
180 | * entered the IPI. See comment in smp_call_function_many. | |
181 | * If we don't have this, then we may miss an entry on the list | |
182 | * and never get another IPI to process it. | |
183 | */ | |
184 | smp_mb(); | |
185 | ||
3d442233 | 186 | /* |
0b13fda1 IM |
187 | * It's ok to use list_for_each_rcu() here even though we may |
188 | * delete 'pos', since list_del_rcu() doesn't clear ->next | |
3d442233 | 189 | */ |
8969a5ed | 190 | list_for_each_entry_rcu(data, &call_function.queue, csd.list) { |
3d442233 JA |
191 | int refs; |
192 | ||
8969a5ed PZ |
193 | spin_lock(&data->lock); |
194 | if (!cpumask_test_cpu(cpu, data->cpumask)) { | |
195 | spin_unlock(&data->lock); | |
3d442233 | 196 | continue; |
8969a5ed PZ |
197 | } |
198 | cpumask_clear_cpu(cpu, data->cpumask); | |
199 | spin_unlock(&data->lock); | |
3d442233 JA |
200 | |
201 | data->csd.func(data->csd.info); | |
202 | ||
203 | spin_lock(&data->lock); | |
3d442233 | 204 | WARN_ON(data->refs == 0); |
8969a5ed PZ |
205 | refs = --data->refs; |
206 | if (!refs) { | |
207 | spin_lock(&call_function.lock); | |
208 | list_del_rcu(&data->csd.list); | |
209 | spin_unlock(&call_function.lock); | |
210 | } | |
3d442233 JA |
211 | spin_unlock(&data->lock); |
212 | ||
213 | if (refs) | |
214 | continue; | |
215 | ||
8969a5ed | 216 | csd_unlock(&data->csd); |
3d442233 | 217 | } |
3d442233 JA |
218 | |
219 | put_cpu(); | |
220 | } | |
221 | ||
222 | /* | |
0b13fda1 IM |
223 | * Invoked by arch to handle an IPI for call function single. Must be |
224 | * called from the arch with interrupts disabled. | |
3d442233 JA |
225 | */ |
226 | void generic_smp_call_function_single_interrupt(void) | |
227 | { | |
228 | struct call_single_queue *q = &__get_cpu_var(call_single_queue); | |
15d0d3b3 | 229 | unsigned int data_flags; |
0b13fda1 | 230 | LIST_HEAD(list); |
3d442233 | 231 | |
15d0d3b3 NP |
232 | spin_lock(&q->lock); |
233 | list_replace_init(&q->list, &list); | |
234 | spin_unlock(&q->lock); | |
3d442233 | 235 | |
15d0d3b3 NP |
236 | while (!list_empty(&list)) { |
237 | struct call_single_data *data; | |
3d442233 | 238 | |
0b13fda1 | 239 | data = list_entry(list.next, struct call_single_data, list); |
15d0d3b3 | 240 | list_del(&data->list); |
3d442233 | 241 | |
3d442233 | 242 | /* |
0b13fda1 IM |
243 | * 'data' can be invalid after this call if flags == 0 |
244 | * (when called through generic_exec_single()), | |
245 | * so save them away before making the call: | |
3d442233 | 246 | */ |
15d0d3b3 NP |
247 | data_flags = data->flags; |
248 | ||
249 | data->func(data->info); | |
250 | ||
8969a5ed | 251 | /* |
0b13fda1 | 252 | * Unlocked CSDs are valid through generic_exec_single(): |
8969a5ed PZ |
253 | */ |
254 | if (data_flags & CSD_FLAG_LOCK) | |
255 | csd_unlock(data); | |
3d442233 JA |
256 | } |
257 | } | |
258 | ||
d7240b98 SR |
259 | static DEFINE_PER_CPU(struct call_single_data, csd_data); |
260 | ||
3d442233 JA |
261 | /* |
262 | * smp_call_function_single - Run a function on a specific CPU | |
263 | * @func: The function to run. This must be fast and non-blocking. | |
264 | * @info: An arbitrary pointer to pass to the function. | |
3d442233 JA |
265 | * @wait: If true, wait until function has completed on other CPUs. |
266 | * | |
267 | * Returns 0 on success, else a negative status code. Note that @wait | |
268 | * will be implicitly turned on in case of allocation failures, since | |
269 | * we fall back to on-stack allocation. | |
270 | */ | |
271 | int smp_call_function_single(int cpu, void (*func) (void *info), void *info, | |
8691e5a8 | 272 | int wait) |
3d442233 | 273 | { |
8969a5ed PZ |
274 | struct call_single_data d = { |
275 | .flags = 0, | |
276 | }; | |
3d442233 | 277 | unsigned long flags; |
0b13fda1 | 278 | int this_cpu; |
f73be6de | 279 | int err = 0; |
3d442233 | 280 | |
0b13fda1 IM |
281 | /* |
282 | * prevent preemption and reschedule on another processor, | |
283 | * as well as CPU removal | |
284 | */ | |
285 | this_cpu = get_cpu(); | |
286 | ||
3d442233 JA |
287 | /* Can deadlock when called with interrupts disabled */ |
288 | WARN_ON(irqs_disabled()); | |
289 | ||
0b13fda1 | 290 | if (cpu == this_cpu) { |
3d442233 JA |
291 | local_irq_save(flags); |
292 | func(info); | |
293 | local_irq_restore(flags); | |
0b13fda1 IM |
294 | } else { |
295 | if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) { | |
296 | struct call_single_data *data = &d; | |
3d442233 | 297 | |
0b13fda1 IM |
298 | if (!wait) |
299 | data = &__get_cpu_var(csd_data); | |
6e275637 | 300 | |
0b13fda1 | 301 | csd_lock(data); |
3d442233 | 302 | |
0b13fda1 IM |
303 | data->func = func; |
304 | data->info = info; | |
305 | generic_exec_single(cpu, data, wait); | |
306 | } else { | |
307 | err = -ENXIO; /* CPU not online */ | |
308 | } | |
3d442233 JA |
309 | } |
310 | ||
311 | put_cpu(); | |
0b13fda1 | 312 | |
f73be6de | 313 | return err; |
3d442233 JA |
314 | } |
315 | EXPORT_SYMBOL(smp_call_function_single); | |
316 | ||
317 | /** | |
318 | * __smp_call_function_single(): Run a function on another CPU | |
319 | * @cpu: The CPU to run on. | |
320 | * @data: Pre-allocated and setup data structure | |
321 | * | |
0b13fda1 IM |
322 | * Like smp_call_function_single(), but allow caller to pass in a |
323 | * pre-allocated data structure. Useful for embedding @data inside | |
324 | * other structures, for instance. | |
3d442233 | 325 | */ |
6e275637 PZ |
326 | void __smp_call_function_single(int cpu, struct call_single_data *data, |
327 | int wait) | |
3d442233 | 328 | { |
6e275637 PZ |
329 | csd_lock(data); |
330 | ||
3d442233 | 331 | /* Can deadlock when called with interrupts disabled */ |
6e275637 | 332 | WARN_ON(wait && irqs_disabled()); |
3d442233 | 333 | |
6e275637 | 334 | generic_exec_single(cpu, data, wait); |
3d442233 JA |
335 | } |
336 | ||
0b13fda1 IM |
337 | /* Deprecated: shim for archs using old arch_send_call_function_ipi API. */ |
338 | ||
ce47d974 | 339 | #ifndef arch_send_call_function_ipi_mask |
0b13fda1 IM |
340 | # define arch_send_call_function_ipi_mask(maskp) \ |
341 | arch_send_call_function_ipi(*(maskp)) | |
ce47d974 RR |
342 | #endif |
343 | ||
3d442233 | 344 | /** |
54b11e6d RR |
345 | * smp_call_function_many(): Run a function on a set of other CPUs. |
346 | * @mask: The set of cpus to run on (only runs on online subset). | |
3d442233 JA |
347 | * @func: The function to run. This must be fast and non-blocking. |
348 | * @info: An arbitrary pointer to pass to the function. | |
0b13fda1 IM |
349 | * @wait: If true, wait (atomically) until function has completed |
350 | * on other CPUs. | |
3d442233 | 351 | * |
3d442233 JA |
352 | * If @wait is true, then returns once @func has returned. Note that @wait |
353 | * will be implicitly turned on in case of allocation failures, since | |
354 | * we fall back to on-stack allocation. | |
355 | * | |
356 | * You must not call this function with disabled interrupts or from a | |
357 | * hardware interrupt handler or from a bottom half handler. Preemption | |
358 | * must be disabled when calling this function. | |
359 | */ | |
54b11e6d | 360 | void smp_call_function_many(const struct cpumask *mask, |
0b13fda1 | 361 | void (*func)(void *), void *info, bool wait) |
3d442233 | 362 | { |
54b11e6d | 363 | struct call_function_data *data; |
3d442233 | 364 | unsigned long flags; |
0b13fda1 | 365 | int cpu, next_cpu, this_cpu = smp_processor_id(); |
3d442233 JA |
366 | |
367 | /* Can deadlock when called with interrupts disabled */ | |
368 | WARN_ON(irqs_disabled()); | |
369 | ||
0b13fda1 | 370 | /* So, what's a CPU they want? Ignoring this one. */ |
54b11e6d | 371 | cpu = cpumask_first_and(mask, cpu_online_mask); |
0b13fda1 | 372 | if (cpu == this_cpu) |
54b11e6d | 373 | cpu = cpumask_next_and(cpu, mask, cpu_online_mask); |
0b13fda1 | 374 | |
54b11e6d RR |
375 | /* No online cpus? We're done. */ |
376 | if (cpu >= nr_cpu_ids) | |
377 | return; | |
378 | ||
379 | /* Do we have another CPU which isn't us? */ | |
380 | next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask); | |
0b13fda1 | 381 | if (next_cpu == this_cpu) |
54b11e6d RR |
382 | next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask); |
383 | ||
384 | /* Fastpath: do that cpu by itself. */ | |
385 | if (next_cpu >= nr_cpu_ids) { | |
386 | smp_call_function_single(cpu, func, info, wait); | |
387 | return; | |
3d442233 JA |
388 | } |
389 | ||
8969a5ed PZ |
390 | data = &__get_cpu_var(cfd_data); |
391 | csd_lock(&data->csd); | |
3d442233 | 392 | |
8969a5ed | 393 | spin_lock_irqsave(&data->lock, flags); |
3d442233 JA |
394 | data->csd.func = func; |
395 | data->csd.info = info; | |
8969a5ed | 396 | cpumask_and(data->cpumask, mask, cpu_online_mask); |
0b13fda1 | 397 | cpumask_clear_cpu(this_cpu, data->cpumask); |
8969a5ed | 398 | data->refs = cpumask_weight(data->cpumask); |
3d442233 | 399 | |
8969a5ed PZ |
400 | spin_lock(&call_function.lock); |
401 | /* | |
402 | * Place entry at the _HEAD_ of the list, so that any cpu still | |
0b13fda1 IM |
403 | * observing the entry in generic_smp_call_function_interrupt() |
404 | * will not miss any other list entries: | |
8969a5ed PZ |
405 | */ |
406 | list_add_rcu(&data->csd.list, &call_function.queue); | |
407 | spin_unlock(&call_function.lock); | |
0b13fda1 | 408 | |
8969a5ed | 409 | spin_unlock_irqrestore(&data->lock, flags); |
3d442233 | 410 | |
561920a0 SS |
411 | /* |
412 | * Make the list addition visible before sending the ipi. | |
0b13fda1 IM |
413 | * (IPIs must obey or appear to obey normal Linux cache |
414 | * coherency rules -- see comment in generic_exec_single). | |
561920a0 SS |
415 | */ |
416 | smp_mb(); | |
417 | ||
3d442233 | 418 | /* Send a message to all CPUs in the map */ |
8969a5ed | 419 | arch_send_call_function_ipi_mask(data->cpumask); |
3d442233 | 420 | |
0b13fda1 | 421 | /* Optionally wait for the CPUs to complete */ |
54b11e6d | 422 | if (wait) |
6e275637 | 423 | csd_lock_wait(&data->csd); |
3d442233 | 424 | } |
54b11e6d | 425 | EXPORT_SYMBOL(smp_call_function_many); |
3d442233 JA |
426 | |
427 | /** | |
428 | * smp_call_function(): Run a function on all other CPUs. | |
429 | * @func: The function to run. This must be fast and non-blocking. | |
430 | * @info: An arbitrary pointer to pass to the function. | |
0b13fda1 IM |
431 | * @wait: If true, wait (atomically) until function has completed |
432 | * on other CPUs. | |
3d442233 | 433 | * |
54b11e6d | 434 | * Returns 0. |
3d442233 JA |
435 | * |
436 | * If @wait is true, then returns once @func has returned; otherwise | |
437 | * it returns just before the target cpu calls @func. In case of allocation | |
438 | * failure, @wait will be implicitly turned on. | |
439 | * | |
440 | * You must not call this function with disabled interrupts or from a | |
441 | * hardware interrupt handler or from a bottom half handler. | |
442 | */ | |
8691e5a8 | 443 | int smp_call_function(void (*func)(void *), void *info, int wait) |
3d442233 | 444 | { |
3d442233 | 445 | preempt_disable(); |
54b11e6d | 446 | smp_call_function_many(cpu_online_mask, func, info, wait); |
3d442233 | 447 | preempt_enable(); |
0b13fda1 | 448 | |
54b11e6d | 449 | return 0; |
3d442233 JA |
450 | } |
451 | EXPORT_SYMBOL(smp_call_function); | |
452 | ||
453 | void ipi_call_lock(void) | |
454 | { | |
8969a5ed | 455 | spin_lock(&call_function.lock); |
3d442233 JA |
456 | } |
457 | ||
458 | void ipi_call_unlock(void) | |
459 | { | |
8969a5ed | 460 | spin_unlock(&call_function.lock); |
3d442233 JA |
461 | } |
462 | ||
463 | void ipi_call_lock_irq(void) | |
464 | { | |
8969a5ed | 465 | spin_lock_irq(&call_function.lock); |
3d442233 JA |
466 | } |
467 | ||
468 | void ipi_call_unlock_irq(void) | |
469 | { | |
8969a5ed | 470 | spin_unlock_irq(&call_function.lock); |
3d442233 | 471 | } |