1 // SPDX-License-Identifier: GPL-2.0-only
3 * Generic helpers for smp ipi calls
5 * (C) Jens Axboe <jens.axboe@oracle.com> 2008
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
29 #include <trace/events/ipi.h>
30 #define CREATE_TRACE_POINTS
31 #include <trace/events/csd.h>
32 #undef CREATE_TRACE_POINTS
35 #include "sched/smp.h"
37 #define CSD_TYPE(_csd) ((_csd)->node.u_flags & CSD_FLAG_TYPE_MASK)
39 struct call_function_data
{
40 call_single_data_t __percpu
*csd
;
41 cpumask_var_t cpumask
;
42 cpumask_var_t cpumask_ipi
;
45 static DEFINE_PER_CPU_ALIGNED(struct call_function_data
, cfd_data
);
47 static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head
, call_single_queue
);
49 static DEFINE_PER_CPU(atomic_t
, trigger_backtrace
) = ATOMIC_INIT(1);
51 static void __flush_smp_call_function_queue(bool warn_cpu_offline
);
53 int smpcfd_prepare_cpu(unsigned int cpu
)
55 struct call_function_data
*cfd
= &per_cpu(cfd_data
, cpu
);
57 if (!zalloc_cpumask_var_node(&cfd
->cpumask
, GFP_KERNEL
,
60 if (!zalloc_cpumask_var_node(&cfd
->cpumask_ipi
, GFP_KERNEL
,
62 free_cpumask_var(cfd
->cpumask
);
65 cfd
->csd
= alloc_percpu(call_single_data_t
);
67 free_cpumask_var(cfd
->cpumask
);
68 free_cpumask_var(cfd
->cpumask_ipi
);
75 int smpcfd_dead_cpu(unsigned int cpu
)
77 struct call_function_data
*cfd
= &per_cpu(cfd_data
, cpu
);
79 free_cpumask_var(cfd
->cpumask
);
80 free_cpumask_var(cfd
->cpumask_ipi
);
81 free_percpu(cfd
->csd
);
85 int smpcfd_dying_cpu(unsigned int cpu
)
88 * The IPIs for the smp-call-function callbacks queued by other
89 * CPUs might arrive late, either due to hardware latencies or
90 * because this CPU disabled interrupts (inside stop-machine)
91 * before the IPIs were sent. So flush out any pending callbacks
92 * explicitly (without waiting for the IPIs to arrive), to
93 * ensure that the outgoing CPU doesn't go offline with work
96 __flush_smp_call_function_queue(false);
101 void __init
call_function_init(void)
105 for_each_possible_cpu(i
)
106 init_llist_head(&per_cpu(call_single_queue
, i
));
108 smpcfd_prepare_cpu(smp_processor_id());
111 static __always_inline
void
112 send_call_function_single_ipi(int cpu
)
114 if (call_function_single_prep_ipi(cpu
)) {
115 trace_ipi_send_cpu(cpu
, _RET_IP_
,
116 generic_smp_call_function_single_interrupt
);
117 arch_send_call_function_single_ipi(cpu
);
121 static __always_inline
void
122 send_call_function_ipi_mask(struct cpumask
*mask
)
124 trace_ipi_send_cpumask(mask
, _RET_IP_
,
125 generic_smp_call_function_single_interrupt
);
126 arch_send_call_function_ipi_mask(mask
);
129 static __always_inline
void
130 csd_do_func(smp_call_func_t func
, void *info
, call_single_data_t
*csd
)
132 trace_csd_function_entry(func
, csd
);
134 trace_csd_function_exit(func
, csd
);
137 #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
139 static DEFINE_STATIC_KEY_MAYBE(CONFIG_CSD_LOCK_WAIT_DEBUG_DEFAULT
, csdlock_debug_enabled
);
142 * Parse the csdlock_debug= kernel boot parameter.
144 * If you need to restore the old "ext" value that once provided
145 * additional debugging information, reapply the following commits:
147 * de7b09ef658d ("locking/csd_lock: Prepare more CSD lock debugging")
148 * a5aabace5fb8 ("locking/csd_lock: Add more data to CSD lock debugging")
150 static int __init
csdlock_debug(char *str
)
153 unsigned int val
= 0;
155 ret
= get_option(&str
, &val
);
158 static_branch_enable(&csdlock_debug_enabled
);
160 static_branch_disable(&csdlock_debug_enabled
);
165 __setup("csdlock_debug=", csdlock_debug
);
167 static DEFINE_PER_CPU(call_single_data_t
*, cur_csd
);
168 static DEFINE_PER_CPU(smp_call_func_t
, cur_csd_func
);
169 static DEFINE_PER_CPU(void *, cur_csd_info
);
171 static ulong csd_lock_timeout
= 5000; /* CSD lock timeout in milliseconds. */
172 module_param(csd_lock_timeout
, ulong
, 0444);
173 static int panic_on_ipistall
; /* CSD panic timeout in milliseconds, 300000 for five minutes. */
174 module_param(panic_on_ipistall
, int, 0444);
176 static atomic_t csd_bug_count
= ATOMIC_INIT(0);
178 /* Record current CSD work for current CPU, NULL to erase. */
179 static void __csd_lock_record(call_single_data_t
*csd
)
182 smp_mb(); /* NULL cur_csd after unlock. */
183 __this_cpu_write(cur_csd
, NULL
);
186 __this_cpu_write(cur_csd_func
, csd
->func
);
187 __this_cpu_write(cur_csd_info
, csd
->info
);
188 smp_wmb(); /* func and info before csd. */
189 __this_cpu_write(cur_csd
, csd
);
190 smp_mb(); /* Update cur_csd before function call. */
191 /* Or before unlock, as the case may be. */
194 static __always_inline
void csd_lock_record(call_single_data_t
*csd
)
196 if (static_branch_unlikely(&csdlock_debug_enabled
))
197 __csd_lock_record(csd
);
200 static int csd_lock_wait_getcpu(call_single_data_t
*csd
)
202 unsigned int csd_type
;
204 csd_type
= CSD_TYPE(csd
);
205 if (csd_type
== CSD_TYPE_ASYNC
|| csd_type
== CSD_TYPE_SYNC
)
206 return csd
->node
.dst
; /* Other CSD_TYPE_ values might not have ->dst. */
211 * Complain if too much time spent waiting. Note that only
212 * the CSD_TYPE_SYNC/ASYNC types provide the destination CPU,
213 * so waiting on other types gets much less information.
215 static bool csd_lock_wait_toolong(call_single_data_t
*csd
, u64 ts0
, u64
*ts1
, int *bug_id
)
221 call_single_data_t
*cpu_cur_csd
;
222 unsigned int flags
= READ_ONCE(csd
->node
.u_flags
);
223 unsigned long long csd_lock_timeout_ns
= csd_lock_timeout
* NSEC_PER_MSEC
;
225 if (!(flags
& CSD_FLAG_LOCK
)) {
226 if (!unlikely(*bug_id
))
228 cpu
= csd_lock_wait_getcpu(csd
);
229 pr_alert("csd: CSD lock (#%d) got unstuck on CPU#%02d, CPU#%02d released the lock.\n",
230 *bug_id
, raw_smp_processor_id(), cpu
);
235 /* How long since we last checked for a stuck CSD lock.*/
236 ts_delta
= ts2
- *ts1
;
237 if (likely(ts_delta
<= csd_lock_timeout_ns
|| csd_lock_timeout_ns
== 0))
240 firsttime
= !*bug_id
;
242 *bug_id
= atomic_inc_return(&csd_bug_count
);
243 cpu
= csd_lock_wait_getcpu(csd
);
244 if (WARN_ONCE(cpu
< 0 || cpu
>= nr_cpu_ids
, "%s: cpu = %d\n", __func__
, cpu
))
248 cpu_cur_csd
= smp_load_acquire(&per_cpu(cur_csd
, cpux
)); /* Before func and info. */
249 /* How long since this CSD lock was stuck. */
250 ts_delta
= ts2
- ts0
;
251 pr_alert("csd: %s non-responsive CSD lock (#%d) on CPU#%d, waiting %llu ns for CPU#%02d %pS(%ps).\n",
252 firsttime
? "Detected" : "Continued", *bug_id
, raw_smp_processor_id(), ts_delta
,
253 cpu
, csd
->func
, csd
->info
);
255 * If the CSD lock is still stuck after 5 minutes, it is unlikely
256 * to become unstuck. Use a signed comparison to avoid triggering
257 * on underflows when the TSC is out of sync between sockets.
259 BUG_ON(panic_on_ipistall
> 0 && (s64
)ts_delta
> ((s64
)panic_on_ipistall
* NSEC_PER_MSEC
));
260 if (cpu_cur_csd
&& csd
!= cpu_cur_csd
) {
261 pr_alert("\tcsd: CSD lock (#%d) handling prior %pS(%ps) request.\n",
262 *bug_id
, READ_ONCE(per_cpu(cur_csd_func
, cpux
)),
263 READ_ONCE(per_cpu(cur_csd_info
, cpux
)));
265 pr_alert("\tcsd: CSD lock (#%d) %s.\n",
266 *bug_id
, !cpu_cur_csd
? "unresponsive" : "handling this request");
269 if (atomic_cmpxchg_acquire(&per_cpu(trigger_backtrace
, cpu
), 1, 0))
272 pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id
, raw_smp_processor_id(), cpu
);
273 arch_send_call_function_single_ipi(cpu
);
284 * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
286 * For non-synchronous ipi calls the csd can still be in use by the
287 * previous function call. For multi-cpu calls its even more interesting
288 * as we'll have to ensure no other cpu is observing our csd.
290 static void __csd_lock_wait(call_single_data_t
*csd
)
295 ts1
= ts0
= sched_clock();
297 if (csd_lock_wait_toolong(csd
, ts0
, &ts1
, &bug_id
))
301 smp_acquire__after_ctrl_dep();
304 static __always_inline
void csd_lock_wait(call_single_data_t
*csd
)
306 if (static_branch_unlikely(&csdlock_debug_enabled
)) {
307 __csd_lock_wait(csd
);
311 smp_cond_load_acquire(&csd
->node
.u_flags
, !(VAL
& CSD_FLAG_LOCK
));
314 static void csd_lock_record(call_single_data_t
*csd
)
318 static __always_inline
void csd_lock_wait(call_single_data_t
*csd
)
320 smp_cond_load_acquire(&csd
->node
.u_flags
, !(VAL
& CSD_FLAG_LOCK
));
324 static __always_inline
void csd_lock(call_single_data_t
*csd
)
327 csd
->node
.u_flags
|= CSD_FLAG_LOCK
;
330 * prevent CPU from reordering the above assignment
331 * to ->flags with any subsequent assignments to other
332 * fields of the specified call_single_data_t structure:
337 static __always_inline
void csd_unlock(call_single_data_t
*csd
)
339 WARN_ON(!(csd
->node
.u_flags
& CSD_FLAG_LOCK
));
342 * ensure we're all done before releasing data:
344 smp_store_release(&csd
->node
.u_flags
, 0);
347 static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t
, csd_data
);
349 void __smp_call_single_queue(int cpu
, struct llist_node
*node
)
352 * We have to check the type of the CSD before queueing it, because
353 * once queued it can have its flags cleared by
354 * flush_smp_call_function_queue()
355 * even if we haven't sent the smp_call IPI yet (e.g. the stopper
356 * executes migration_cpu_stop() on the remote CPU).
358 if (trace_csd_queue_cpu_enabled()) {
359 call_single_data_t
*csd
;
360 smp_call_func_t func
;
362 csd
= container_of(node
, call_single_data_t
, node
.llist
);
363 func
= CSD_TYPE(csd
) == CSD_TYPE_TTWU
?
364 sched_ttwu_pending
: csd
->func
;
366 trace_csd_queue_cpu(cpu
, _RET_IP_
, func
, csd
);
370 * The list addition should be visible to the target CPU when it pops
371 * the head of the list to pull the entry off it in the IPI handler
372 * because of normal cache coherency rules implied by the underlying
375 * If IPIs can go out of order to the cache coherency protocol
376 * in an architecture, sufficient synchronisation should be added
377 * to arch code to make it appear to obey cache coherency WRT
378 * locking and barrier primitives. Generic code isn't really
379 * equipped to do the right thing...
381 if (llist_add(node
, &per_cpu(call_single_queue
, cpu
)))
382 send_call_function_single_ipi(cpu
);
386 * Insert a previously allocated call_single_data_t element
387 * for execution on the given CPU. data must already have
388 * ->func, ->info, and ->flags set.
390 static int generic_exec_single(int cpu
, call_single_data_t
*csd
)
392 if (cpu
== smp_processor_id()) {
393 smp_call_func_t func
= csd
->func
;
394 void *info
= csd
->info
;
398 * We can unlock early even for the synchronous on-stack case,
399 * since we're doing this from the same CPU..
401 csd_lock_record(csd
);
403 local_irq_save(flags
);
404 csd_do_func(func
, info
, NULL
);
405 csd_lock_record(NULL
);
406 local_irq_restore(flags
);
410 if ((unsigned)cpu
>= nr_cpu_ids
|| !cpu_online(cpu
)) {
415 __smp_call_single_queue(cpu
, &csd
->node
.llist
);
421 * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks
423 * Invoked by arch to handle an IPI for call function single.
424 * Must be called with interrupts disabled.
426 void generic_smp_call_function_single_interrupt(void)
428 __flush_smp_call_function_queue(true);
432 * __flush_smp_call_function_queue - Flush pending smp-call-function callbacks
434 * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
435 * offline CPU. Skip this check if set to 'false'.
437 * Flush any pending smp-call-function callbacks queued on this CPU. This is
438 * invoked by the generic IPI handler, as well as by a CPU about to go offline,
439 * to ensure that all pending IPI callbacks are run before it goes completely
442 * Loop through the call_single_queue and run all the queued callbacks.
443 * Must be called with interrupts disabled.
445 static void __flush_smp_call_function_queue(bool warn_cpu_offline
)
447 call_single_data_t
*csd
, *csd_next
;
448 struct llist_node
*entry
, *prev
;
449 struct llist_head
*head
;
453 lockdep_assert_irqs_disabled();
455 /* Allow waiters to send backtrace NMI from here onwards */
456 tbt
= this_cpu_ptr(&trigger_backtrace
);
457 atomic_set_release(tbt
, 1);
459 head
= this_cpu_ptr(&call_single_queue
);
460 entry
= llist_del_all(head
);
461 entry
= llist_reverse_order(entry
);
463 /* There shouldn't be any pending callbacks on an offline CPU. */
464 if (unlikely(warn_cpu_offline
&& !cpu_online(smp_processor_id()) &&
465 !warned
&& entry
!= NULL
)) {
467 WARN(1, "IPI on offline CPU %d\n", smp_processor_id());
470 * We don't have to use the _safe() variant here
471 * because we are not invoking the IPI handlers yet.
473 llist_for_each_entry(csd
, entry
, node
.llist
) {
474 switch (CSD_TYPE(csd
)) {
477 case CSD_TYPE_IRQ_WORK
:
478 pr_warn("IPI callback %pS sent to offline CPU\n",
483 pr_warn("IPI task-wakeup sent to offline CPU\n");
487 pr_warn("IPI callback, unknown type %d, sent to offline CPU\n",
495 * First; run all SYNC callbacks, people are waiting for us.
498 llist_for_each_entry_safe(csd
, csd_next
, entry
, node
.llist
) {
499 /* Do we wait until *after* callback? */
500 if (CSD_TYPE(csd
) == CSD_TYPE_SYNC
) {
501 smp_call_func_t func
= csd
->func
;
502 void *info
= csd
->info
;
505 prev
->next
= &csd_next
->node
.llist
;
507 entry
= &csd_next
->node
.llist
;
510 csd_lock_record(csd
);
511 csd_do_func(func
, info
, csd
);
513 csd_lock_record(NULL
);
515 prev
= &csd
->node
.llist
;
523 * Second; run all !SYNC callbacks.
526 llist_for_each_entry_safe(csd
, csd_next
, entry
, node
.llist
) {
527 int type
= CSD_TYPE(csd
);
529 if (type
!= CSD_TYPE_TTWU
) {
531 prev
->next
= &csd_next
->node
.llist
;
533 entry
= &csd_next
->node
.llist
;
536 if (type
== CSD_TYPE_ASYNC
) {
537 smp_call_func_t func
= csd
->func
;
538 void *info
= csd
->info
;
540 csd_lock_record(csd
);
542 csd_do_func(func
, info
, csd
);
543 csd_lock_record(NULL
);
544 } else if (type
== CSD_TYPE_IRQ_WORK
) {
545 irq_work_single(csd
);
549 prev
= &csd
->node
.llist
;
554 * Third; only CSD_TYPE_TTWU is left, issue those.
557 csd
= llist_entry(entry
, typeof(*csd
), node
.llist
);
558 csd_do_func(sched_ttwu_pending
, entry
, csd
);
564 * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
565 * from task context (idle, migration thread)
567 * When TIF_POLLING_NRFLAG is supported and a CPU is in idle and has it
568 * set, then remote CPUs can avoid sending IPIs and wake the idle CPU by
569 * setting TIF_NEED_RESCHED. The idle task on the woken up CPU has to
570 * handle queued SMP function calls before scheduling.
572 * The migration thread has to ensure that an eventually pending wakeup has
573 * been handled before it migrates a task.
575 void flush_smp_call_function_queue(void)
577 unsigned int was_pending
;
580 if (llist_empty(this_cpu_ptr(&call_single_queue
)))
583 local_irq_save(flags
);
584 /* Get the already pending soft interrupts for RT enabled kernels */
585 was_pending
= local_softirq_pending();
586 __flush_smp_call_function_queue(true);
587 if (local_softirq_pending())
588 do_softirq_post_smp_call_flush(was_pending
);
590 local_irq_restore(flags
);
594 * smp_call_function_single - Run a function on a specific CPU
595 * @func: The function to run. This must be fast and non-blocking.
596 * @info: An arbitrary pointer to pass to the function.
597 * @wait: If true, wait until function has completed on other CPUs.
599 * Returns 0 on success, else a negative status code.
601 int smp_call_function_single(int cpu
, smp_call_func_t func
, void *info
,
604 call_single_data_t
*csd
;
605 call_single_data_t csd_stack
= {
606 .node
= { .u_flags
= CSD_FLAG_LOCK
| CSD_TYPE_SYNC
, },
612 * prevent preemption and reschedule on another processor,
613 * as well as CPU removal
615 this_cpu
= get_cpu();
618 * Can deadlock when called with interrupts disabled.
619 * We allow cpu's that are not yet online though, as no one else can
620 * send smp call function interrupt to this cpu and as such deadlocks
623 WARN_ON_ONCE(cpu_online(this_cpu
) && irqs_disabled()
624 && !oops_in_progress
);
627 * When @wait we can deadlock when we interrupt between llist_add() and
628 * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
629 * csd_lock() on because the interrupt context uses the same csd
632 WARN_ON_ONCE(!in_task());
636 csd
= this_cpu_ptr(&csd_data
);
642 #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
643 csd
->node
.src
= smp_processor_id();
647 err
= generic_exec_single(cpu
, csd
);
656 EXPORT_SYMBOL(smp_call_function_single
);
659 * smp_call_function_single_async() - Run an asynchronous function on a
661 * @cpu: The CPU to run on.
662 * @csd: Pre-allocated and setup data structure
664 * Like smp_call_function_single(), but the call is asynchonous and
665 * can thus be done from contexts with disabled interrupts.
667 * The caller passes his own pre-allocated data structure
668 * (ie: embedded in an object) and is responsible for synchronizing it
669 * such that the IPIs performed on the @csd are strictly serialized.
671 * If the function is called with one csd which has not yet been
672 * processed by previous call to smp_call_function_single_async(), the
673 * function will return immediately with -EBUSY showing that the csd
674 * object is still in progress.
676 * NOTE: Be careful, there is unfortunately no current debugging facility to
677 * validate the correctness of this serialization.
679 * Return: %0 on success or negative errno value on error
681 int smp_call_function_single_async(int cpu
, call_single_data_t
*csd
)
687 if (csd
->node
.u_flags
& CSD_FLAG_LOCK
) {
692 csd
->node
.u_flags
= CSD_FLAG_LOCK
;
695 err
= generic_exec_single(cpu
, csd
);
702 EXPORT_SYMBOL_GPL(smp_call_function_single_async
);
705 * smp_call_function_any - Run a function on any of the given cpus
706 * @mask: The mask of cpus it can run on.
707 * @func: The function to run. This must be fast and non-blocking.
708 * @info: An arbitrary pointer to pass to the function.
709 * @wait: If true, wait until function has completed.
711 * Returns 0 on success, else a negative status code (if no cpus were online).
713 * Selection preference:
714 * 1) current cpu if in @mask
715 * 2) any cpu of current node if in @mask
716 * 3) any other online cpu in @mask
718 int smp_call_function_any(const struct cpumask
*mask
,
719 smp_call_func_t func
, void *info
, int wait
)
722 const struct cpumask
*nodemask
;
725 /* Try for same CPU (cheapest) */
727 if (cpumask_test_cpu(cpu
, mask
))
730 /* Try for same node. */
731 nodemask
= cpumask_of_node(cpu_to_node(cpu
));
732 for (cpu
= cpumask_first_and(nodemask
, mask
); cpu
< nr_cpu_ids
;
733 cpu
= cpumask_next_and(cpu
, nodemask
, mask
)) {
738 /* Any online will do: smp_call_function_single handles nr_cpu_ids. */
739 cpu
= cpumask_any_and(mask
, cpu_online_mask
);
741 ret
= smp_call_function_single(cpu
, func
, info
, wait
);
745 EXPORT_SYMBOL_GPL(smp_call_function_any
);
748 * Flags to be used as scf_flags argument of smp_call_function_many_cond().
750 * %SCF_WAIT: Wait until function execution is completed
751 * %SCF_RUN_LOCAL: Run also locally if local cpu is set in cpumask
753 #define SCF_WAIT (1U << 0)
754 #define SCF_RUN_LOCAL (1U << 1)
756 static void smp_call_function_many_cond(const struct cpumask
*mask
,
757 smp_call_func_t func
, void *info
,
758 unsigned int scf_flags
,
759 smp_cond_func_t cond_func
)
761 int cpu
, last_cpu
, this_cpu
= smp_processor_id();
762 struct call_function_data
*cfd
;
763 bool wait
= scf_flags
& SCF_WAIT
;
765 bool run_remote
= false;
766 bool run_local
= false;
768 lockdep_assert_preemption_disabled();
771 * Can deadlock when called with interrupts disabled.
772 * We allow cpu's that are not yet online though, as no one else can
773 * send smp call function interrupt to this cpu and as such deadlocks
776 if (cpu_online(this_cpu
) && !oops_in_progress
&&
777 !early_boot_irqs_disabled
)
778 lockdep_assert_irqs_enabled();
781 * When @wait we can deadlock when we interrupt between llist_add() and
782 * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
783 * csd_lock() on because the interrupt context uses the same csd
786 WARN_ON_ONCE(!in_task());
788 /* Check if we need local execution. */
789 if ((scf_flags
& SCF_RUN_LOCAL
) && cpumask_test_cpu(this_cpu
, mask
))
792 /* Check if we need remote execution, i.e., any CPU excluding this one. */
793 cpu
= cpumask_first_and(mask
, cpu_online_mask
);
795 cpu
= cpumask_next_and(cpu
, mask
, cpu_online_mask
);
796 if (cpu
< nr_cpu_ids
)
800 cfd
= this_cpu_ptr(&cfd_data
);
801 cpumask_and(cfd
->cpumask
, mask
, cpu_online_mask
);
802 __cpumask_clear_cpu(this_cpu
, cfd
->cpumask
);
804 cpumask_clear(cfd
->cpumask_ipi
);
805 for_each_cpu(cpu
, cfd
->cpumask
) {
806 call_single_data_t
*csd
= per_cpu_ptr(cfd
->csd
, cpu
);
808 if (cond_func
&& !cond_func(cpu
, info
)) {
809 __cpumask_clear_cpu(cpu
, cfd
->cpumask
);
815 csd
->node
.u_flags
|= CSD_TYPE_SYNC
;
818 #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
819 csd
->node
.src
= smp_processor_id();
822 trace_csd_queue_cpu(cpu
, _RET_IP_
, func
, csd
);
824 if (llist_add(&csd
->node
.llist
, &per_cpu(call_single_queue
, cpu
))) {
825 __cpumask_set_cpu(cpu
, cfd
->cpumask_ipi
);
832 * Choose the most efficient way to send an IPI. Note that the
833 * number of CPUs might be zero due to concurrent changes to the
837 send_call_function_single_ipi(last_cpu
);
838 else if (likely(nr_cpus
> 1))
839 send_call_function_ipi_mask(cfd
->cpumask_ipi
);
842 if (run_local
&& (!cond_func
|| cond_func(this_cpu
, info
))) {
845 local_irq_save(flags
);
846 csd_do_func(func
, info
, NULL
);
847 local_irq_restore(flags
);
850 if (run_remote
&& wait
) {
851 for_each_cpu(cpu
, cfd
->cpumask
) {
852 call_single_data_t
*csd
;
854 csd
= per_cpu_ptr(cfd
->csd
, cpu
);
861 * smp_call_function_many(): Run a function on a set of CPUs.
862 * @mask: The set of cpus to run on (only runs on online subset).
863 * @func: The function to run. This must be fast and non-blocking.
864 * @info: An arbitrary pointer to pass to the function.
865 * @wait: Bitmask that controls the operation. If %SCF_WAIT is set, wait
866 * (atomically) until function has completed on other CPUs. If
867 * %SCF_RUN_LOCAL is set, the function will also be run locally
868 * if the local CPU is set in the @cpumask.
870 * If @wait is true, then returns once @func has returned.
872 * You must not call this function with disabled interrupts or from a
873 * hardware interrupt handler or from a bottom half handler. Preemption
874 * must be disabled when calling this function.
876 void smp_call_function_many(const struct cpumask
*mask
,
877 smp_call_func_t func
, void *info
, bool wait
)
879 smp_call_function_many_cond(mask
, func
, info
, wait
* SCF_WAIT
, NULL
);
881 EXPORT_SYMBOL(smp_call_function_many
);
884 * smp_call_function(): Run a function on all other CPUs.
885 * @func: The function to run. This must be fast and non-blocking.
886 * @info: An arbitrary pointer to pass to the function.
887 * @wait: If true, wait (atomically) until function has completed
892 * If @wait is true, then returns once @func has returned; otherwise
893 * it returns just before the target cpu calls @func.
895 * You must not call this function with disabled interrupts or from a
896 * hardware interrupt handler or from a bottom half handler.
898 void smp_call_function(smp_call_func_t func
, void *info
, int wait
)
901 smp_call_function_many(cpu_online_mask
, func
, info
, wait
);
904 EXPORT_SYMBOL(smp_call_function
);
906 /* Setup configured maximum number of CPUs to activate */
907 unsigned int setup_max_cpus
= NR_CPUS
;
908 EXPORT_SYMBOL(setup_max_cpus
);
912 * Setup routine for controlling SMP activation
914 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
915 * activation entirely (the MPS table probe still happens, though).
917 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
918 * greater than 0, limits the maximum number of CPUs activated in
922 void __weak __init
arch_disable_smp_support(void) { }
924 static int __init
nosmp(char *str
)
927 arch_disable_smp_support();
932 early_param("nosmp", nosmp
);
934 /* this is hard limit */
935 static int __init
nrcpus(char *str
)
939 if (get_option(&str
, &nr_cpus
) && nr_cpus
> 0 && nr_cpus
< nr_cpu_ids
)
940 set_nr_cpu_ids(nr_cpus
);
945 early_param("nr_cpus", nrcpus
);
947 static int __init
maxcpus(char *str
)
949 get_option(&str
, &setup_max_cpus
);
950 if (setup_max_cpus
== 0)
951 arch_disable_smp_support();
956 early_param("maxcpus", maxcpus
);
958 #if (NR_CPUS > 1) && !defined(CONFIG_FORCE_NR_CPUS)
959 /* Setup number of possible processor ids */
960 unsigned int nr_cpu_ids __read_mostly
= NR_CPUS
;
961 EXPORT_SYMBOL(nr_cpu_ids
);
964 /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
965 void __init
setup_nr_cpu_ids(void)
967 set_nr_cpu_ids(find_last_bit(cpumask_bits(cpu_possible_mask
), NR_CPUS
) + 1);
970 /* Called by boot processor to activate the rest. */
971 void __init
smp_init(void)
973 int num_nodes
, num_cpus
;
976 cpuhp_threads_init();
978 pr_info("Bringing up secondary CPUs ...\n");
980 bringup_nonboot_cpus(setup_max_cpus
);
982 num_nodes
= num_online_nodes();
983 num_cpus
= num_online_cpus();
984 pr_info("Brought up %d node%s, %d CPU%s\n",
985 num_nodes
, (num_nodes
> 1 ? "s" : ""),
986 num_cpus
, (num_cpus
> 1 ? "s" : ""));
988 /* Any cleanup work */
989 smp_cpus_done(setup_max_cpus
);
993 * on_each_cpu_cond(): Call a function on each processor for which
994 * the supplied function cond_func returns true, optionally waiting
995 * for all the required CPUs to finish. This may include the local
997 * @cond_func: A callback function that is passed a cpu id and
998 * the info parameter. The function is called
999 * with preemption disabled. The function should
1000 * return a blooean value indicating whether to IPI
1001 * the specified CPU.
1002 * @func: The function to run on all applicable CPUs.
1003 * This must be fast and non-blocking.
1004 * @info: An arbitrary pointer to pass to both functions.
1005 * @wait: If true, wait (atomically) until function has
1006 * completed on other CPUs.
1008 * Preemption is disabled to protect against CPUs going offline but not online.
1009 * CPUs going online during the call will not be seen or sent an IPI.
1011 * You must not call this function with disabled interrupts or
1012 * from a hardware interrupt handler or from a bottom half handler.
1014 void on_each_cpu_cond_mask(smp_cond_func_t cond_func
, smp_call_func_t func
,
1015 void *info
, bool wait
, const struct cpumask
*mask
)
1017 unsigned int scf_flags
= SCF_RUN_LOCAL
;
1020 scf_flags
|= SCF_WAIT
;
1023 smp_call_function_many_cond(mask
, func
, info
, scf_flags
, cond_func
);
1026 EXPORT_SYMBOL(on_each_cpu_cond_mask
);
1028 static void do_nothing(void *unused
)
1033 * kick_all_cpus_sync - Force all cpus out of idle
1035 * Used to synchronize the update of pm_idle function pointer. It's
1036 * called after the pointer is updated and returns after the dummy
1037 * callback function has been executed on all cpus. The execution of
1038 * the function can only happen on the remote cpus after they have
1039 * left the idle function which had been called via pm_idle function
1040 * pointer. So it's guaranteed that nothing uses the previous pointer
1043 void kick_all_cpus_sync(void)
1045 /* Make sure the change is visible before we kick the cpus */
1047 smp_call_function(do_nothing
, NULL
, 1);
1049 EXPORT_SYMBOL_GPL(kick_all_cpus_sync
);
1052 * wake_up_all_idle_cpus - break all cpus out of idle
1053 * wake_up_all_idle_cpus try to break all cpus which is in idle state even
1054 * including idle polling cpus, for non-idle cpus, we will do nothing
1057 void wake_up_all_idle_cpus(void)
1061 for_each_possible_cpu(cpu
) {
1063 if (cpu
!= smp_processor_id() && cpu_online(cpu
))
1064 wake_up_if_idle(cpu
);
1068 EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus
);
1071 * struct smp_call_on_cpu_struct - Call a function on a specific CPU
1072 * @work: &work_struct
1073 * @done: &completion to signal
1074 * @func: function to call
1075 * @data: function's data argument
1076 * @ret: return value from @func
1077 * @cpu: target CPU (%-1 for any CPU)
1079 * Used to call a function on a specific cpu and wait for it to return.
1080 * Optionally make sure the call is done on a specified physical cpu via vcpu
1081 * pinning in order to support virtualized environments.
1083 struct smp_call_on_cpu_struct
{
1084 struct work_struct work
;
1085 struct completion done
;
1086 int (*func
)(void *);
1092 static void smp_call_on_cpu_callback(struct work_struct
*work
)
1094 struct smp_call_on_cpu_struct
*sscs
;
1096 sscs
= container_of(work
, struct smp_call_on_cpu_struct
, work
);
1098 hypervisor_pin_vcpu(sscs
->cpu
);
1099 sscs
->ret
= sscs
->func(sscs
->data
);
1101 hypervisor_pin_vcpu(-1);
1103 complete(&sscs
->done
);
1106 int smp_call_on_cpu(unsigned int cpu
, int (*func
)(void *), void *par
, bool phys
)
1108 struct smp_call_on_cpu_struct sscs
= {
1109 .done
= COMPLETION_INITIALIZER_ONSTACK(sscs
.done
),
1112 .cpu
= phys
? cpu
: -1,
1115 INIT_WORK_ONSTACK(&sscs
.work
, smp_call_on_cpu_callback
);
1117 if (cpu
>= nr_cpu_ids
|| !cpu_online(cpu
))
1120 queue_work_on(cpu
, system_wq
, &sscs
.work
);
1121 wait_for_completion(&sscs
.done
);
1125 EXPORT_SYMBOL_GPL(smp_call_on_cpu
);