cregit-Linux how code gets into the kernel

Release 4.18 kernel/cpu.c

Directory: kernel
/* CPU control.
 * (C) 2001, 2002, 2003, 2004 Rusty Russell
 *
 * This code is licenced under the GPL.
 */
#include <linux/proc_fs.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/notifier.h>
#include <linux/sched/signal.h>
#include <linux/sched/hotplug.h>
#include <linux/sched/task.h>
#include <linux/unistd.h>
#include <linux/cpu.h>
#include <linux/oom.h>
#include <linux/rcupdate.h>
#include <linux/export.h>
#include <linux/bug.h>
#include <linux/kthread.h>
#include <linux/stop_machine.h>
#include <linux/mutex.h>
#include <linux/gfp.h>
#include <linux/suspend.h>
#include <linux/lockdep.h>
#include <linux/tick.h>
#include <linux/irq.h>
#include <linux/nmi.h>
#include <linux/smpboot.h>
#include <linux/relay.h>
#include <linux/slab.h>
#include <linux/percpu-rwsem.h>

#include <trace/events/power.h>

#define CREATE_TRACE_POINTS
#include <trace/events/cpuhp.h>

#include "smpboot.h"

/**
 * cpuhp_cpu_state - Per cpu hotplug state storage
 * @state:      The current cpu state
 * @target:     The target state
 * @thread:     Pointer to the hotplug thread
 * @should_run: Thread should execute
 * @rollback:   Perform a rollback
 * @single:     Single callback invocation
 * @bringup:    Single callback bringup or teardown selector
 * @cb_state:   The state for a single callback (install/uninstall)
 * @result:     Result of the operation
 * @done_up:    Signal completion to the issuer of the task for cpu-up
 * @done_down:  Signal completion to the issuer of the task for cpu-down
 */

struct cpuhp_cpu_state {
	
enum cpuhp_state	state;
	
enum cpuhp_state	target;
	
enum cpuhp_state	fail;
#ifdef CONFIG_SMP
	
struct task_struct	*thread;
	
bool			should_run;
	
bool			rollback;
	
bool			single;
	
bool			bringup;
	
struct hlist_node	*node;
	
struct hlist_node	*last;
	
enum cpuhp_state	cb_state;
	
int			result;
	
struct completion	done_up;
	
struct completion	done_down;
#endif
};

static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state) = {
	.fail = CPUHP_INVALID,
};

#if defined(CONFIG_LOCKDEP) && defined(CONFIG_SMP)

static struct lockdep_map cpuhp_state_up_map =
	STATIC_LOCKDEP_MAP_INIT("cpuhp_state-up", &cpuhp_state_up_map);

static struct lockdep_map cpuhp_state_down_map =
	STATIC_LOCKDEP_MAP_INIT("cpuhp_state-down", &cpuhp_state_down_map);



static inline void cpuhp_lock_acquire(bool bringup) { lock_map_acquire(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map); }

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static inline void cpuhp_lock_release(bool bringup) { lock_map_release(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map); }

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#else
static inline void cpuhp_lock_acquire(bool bringup) { }

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static inline void cpuhp_lock_release(bool bringup) { }

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#endif /** * cpuhp_step - Hotplug state machine step * @name: Name of the step * @startup: Startup function of the step * @teardown: Teardown function of the step * @skip_onerr: Do not invoke the functions on error rollback * Will go away once the notifiers are gone * @cant_stop: Bringup/teardown can't be stopped at this step */ struct cpuhp_step { const char *name; union { int (*single)(unsigned int cpu); int (*multi)(unsigned int cpu, struct hlist_node *node); } startup; union { int (*single)(unsigned int cpu); int (*multi)(unsigned int cpu, struct hlist_node *node); } teardown; struct hlist_head list; bool skip_onerr; bool cant_stop; bool multi_instance; }; static DEFINE_MUTEX(cpuhp_state_mutex); static struct cpuhp_step cpuhp_hp_states[];
static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state) { return cpuhp_hp_states + state; }

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/** * cpuhp_invoke_callback _ Invoke the callbacks for a given state * @cpu: The cpu for which the callback should be invoked * @state: The state to do callbacks for * @bringup: True if the bringup callback should be invoked * @node: For multi-instance, do a single entry callback for install/remove * @lastp: For multi-instance rollback, remember how far we got * * Called from cpu hotplug and from the state register machinery. */
static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state, bool bringup, struct hlist_node *node, struct hlist_node **lastp) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); struct cpuhp_step *step = cpuhp_get_step(state); int (*cbm)(unsigned int cpu, struct hlist_node *node); int (*cb)(unsigned int cpu); int ret, cnt; if (st->fail == state) { st->fail = CPUHP_INVALID; if (!(bringup ? step->startup.single : step->teardown.single)) return 0; return -EAGAIN; } if (!step->multi_instance) { WARN_ON_ONCE(lastp && *lastp); cb = bringup ? step->startup.single : step->teardown.single; if (!cb) return 0; trace_cpuhp_enter(cpu, st->target, state, cb); ret = cb(cpu); trace_cpuhp_exit(cpu, st->state, state, ret); return ret; } cbm = bringup ? step->startup.multi : step->teardown.multi; if (!cbm) return 0; /* Single invocation for instance add/remove */ if (node) { WARN_ON_ONCE(lastp && *lastp); trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node); ret = cbm(cpu, node); trace_cpuhp_exit(cpu, st->state, state, ret); return ret; } /* State transition. Invoke on all instances */ cnt = 0; hlist_for_each(node, &step->list) { if (lastp && node == *lastp) break; trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node); ret = cbm(cpu, node); trace_cpuhp_exit(cpu, st->state, state, ret); if (ret) { if (!lastp) goto err; *lastp = node; return ret; } cnt++; } if (lastp) *lastp = NULL; return 0; err: /* Rollback the instances if one failed */ cbm = !bringup ? step->startup.multi : step->teardown.multi; if (!cbm) return ret; hlist_for_each(node, &step->list) { if (!cnt--) break; trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node); ret = cbm(cpu, node); trace_cpuhp_exit(cpu, st->state, state, ret); /* * Rollback must not fail, */ WARN_ON_ONCE(ret); } return ret; }

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Peter Zijlstra13428.69%342.86%
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#ifdef CONFIG_SMP
static bool cpuhp_is_ap_state(enum cpuhp_state state) { /* * The extra check for CPUHP_TEARDOWN_CPU is only for documentation * purposes as that state is handled explicitly in cpu_down. */ return state > CPUHP_BRINGUP_CPU && state != CPUHP_TEARDOWN_CPU; }

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Arnd Bergmann20100.00%1100.00%
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static inline void wait_for_ap_thread(struct cpuhp_cpu_state *st, bool bringup) { struct completion *done = bringup ? &st->done_up : &st->done_down; wait_for_completion(done); }

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static inline void complete_ap_thread(struct cpuhp_cpu_state *st, bool bringup) { struct completion *done = bringup ? &st->done_up : &st->done_down; complete(done); }

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/* * The former STARTING/DYING states, ran with IRQs disabled and must not fail. */
static bool cpuhp_is_atomic_state(enum cpuhp_state state) { return CPUHP_AP_IDLE_DEAD <= state && state < CPUHP_AP_ONLINE; }

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Peter Zijlstra19100.00%1100.00%
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/* Serializes the updates to cpu_online_mask, cpu_present_mask */ static DEFINE_MUTEX(cpu_add_remove_lock); bool cpuhp_tasks_frozen; EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen); /* * The following two APIs (cpu_maps_update_begin/done) must be used when * attempting to serialize the updates to cpu_online_mask & cpu_present_mask. */
void cpu_maps_update_begin(void) { mutex_lock(&cpu_add_remove_lock); }

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void cpu_maps_update_done(void) { mutex_unlock(&cpu_add_remove_lock); }

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Lai Jiangshan13100.00%1100.00%
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/* * If set, cpu_up and cpu_down will return -EBUSY and do nothing. * Should always be manipulated under cpu_add_remove_lock */ static int cpu_hotplug_disabled; #ifdef CONFIG_HOTPLUG_CPU DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock);
void cpus_read_lock(void) { percpu_down_read(&cpu_hotplug_lock); }

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Ashok Raj17.69%114.29%
David Hildenbrand17.69%114.29%
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EXPORT_SYMBOL_GPL(cpus_read_lock);
void cpus_read_unlock(void) { percpu_up_read(&cpu_hotplug_lock); }

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Ashok Raj1076.92%133.33%
Thomas Gleixner323.08%266.67%
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EXPORT_SYMBOL_GPL(cpus_read_unlock);
void cpus_write_lock(void) { percpu_down_write(&cpu_hotplug_lock); }

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void cpus_write_unlock(void) { percpu_up_write(&cpu_hotplug_lock); }

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void lockdep_assert_cpus_held(void) { percpu_rwsem_assert_held(&cpu_hotplug_lock); }

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/* * Wait for currently running CPU hotplug operations to complete (if any) and * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the * hotplug path before performing hotplug operations. So acquiring that lock * guarantees mutual exclusion from any currently running hotplug operations. */
void cpu_hotplug_disable(void) { cpu_maps_update_begin(); cpu_hotplug_disabled++; cpu_maps_update_done(); }

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EXPORT_SYMBOL_GPL(cpu_hotplug_disable);
static void __cpu_hotplug_enable(void) { if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n")) return; cpu_hotplug_disabled--; }

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void cpu_hotplug_enable(void) { cpu_maps_update_begin(); __cpu_hotplug_enable(); cpu_maps_update_done(); }

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EXPORT_SYMBOL_GPL(cpu_hotplug_enable); #endif /* CONFIG_HOTPLUG_CPU */
static inline enum cpuhp_state cpuhp_set_state(struct cpuhp_cpu_state *st, enum cpuhp_state target) { enum cpuhp_state prev_state = st->state; st->rollback = false; st->last = NULL; st->target = target; st->single = false; st->bringup = st->state < target; return prev_state; }

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Peter Zijlstra5588.71%150.00%
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static inline void cpuhp_reset_state(struct cpuhp_cpu_state *st, enum cpuhp_state prev_state) { st->rollback = true; /* * If we have st->last we need to undo partial multi_instance of this * state first. Otherwise start undo at the previous state. */ if (!st->last) { if (st->bringup) st->state--; else st->state++; } st->target = prev_state; st->bringup = !st->bringup; }

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/* Regular hotplug invocation of the AP hotplug thread */
static void __cpuhp_kick_ap(struct cpuhp_cpu_state *st) { if (!st->single && st->state == st->target) return; st->result = 0; /* * Make sure the above stores are visible before should_run becomes * true. Paired with the mb() above in cpuhp_thread_fun() */ smp_mb(); st->should_run = true; wake_up_process(st->thread); wait_for_ap_thread(st, st->bringup); }

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static int cpuhp_kick_ap(struct cpuhp_cpu_state *st, enum cpuhp_state target) { enum cpuhp_state prev_state; int ret; prev_state = cpuhp_set_state(st, target); __cpuhp_kick_ap(st); if ((ret = st->result)) { cpuhp_reset_state(st, prev_state); __cpuhp_kick_ap(st); } return ret; }

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Peter Zijlstra3758.73%150.00%
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static int bringup_wait_for_ap(unsigned int cpu) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); /* Wait for the CPU to reach CPUHP_AP_ONLINE_IDLE */ wait_for_ap_thread(st, true); if (WARN_ON_ONCE((!cpu_online(cpu)))) return -ECANCELED; /* Unpark the stopper thread and the hotplug thread of the target cpu */ stop_machine_unpark(cpu); kthread_unpark(st->thread); if (st->target <= CPUHP_AP_ONLINE_IDLE) return 0; return cpuhp_kick_ap(st, st->target); }

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static int bringup_cpu(unsigned int cpu) { struct task_struct *idle = idle_thread_get(cpu); int ret; /* * Some architectures have to walk the irq descriptors to * setup the vector space for the cpu which comes online. * Prevent irq alloc/free across the bringup. */ irq_lock_sparse(); /* Arch-specific enabling code. */ ret = __cpu_up(cpu, idle); irq_unlock_sparse(); if (ret) return ret; return bringup_wait_for_ap(cpu); }

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/* * Hotplug state machine related functions */
static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st) { for (st->state--; st->state > st->target; st->state--) { struct cpuhp_step *step = cpuhp_get_step(st->state); if (!step->skip_onerr) cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL); } }

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static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, enum cpuhp_state target) { enum cpuhp_state prev_state = st->state; int ret = 0; while (st->state < target) { st->state++; ret = cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL); if (ret) { st->target = prev_state; undo_cpu_up(cpu, st); break; } } return ret; }

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/* * The cpu hotplug threads manage the bringup and teardown of the cpus */
static void cpuhp_create(unsigned int cpu) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); init_completion(&st->done_up); init_completion(&st->done_down); }

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static int cpuhp_should_run(unsigned int cpu) { struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); return st->should_run; }

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/* * Execute teardown/startup callbacks on the plugged cpu. Also used to invoke * callbacks when a state gets [un]installed at runtime. * * Each invocation of this function by the smpboot thread does a single AP * state callback. * * It has 3 modes of operation: * - single: runs st->cb_state * - up: runs ++st->state, while st->state < st->target * - down: runs st->state--, while st->state > st->target * * When complete or on error, should_run is cleared and the completion is fired. */
static void cpuhp_thread_fun(unsigned int cpu) { struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); bool bringup = st->bringup; enum cpuhp_state state; /* * ACQUIRE for the cpuhp_should_run() load of ->should_run. Ensures * that if we see ->should_run we also see the rest of the state. */ smp_mb(); if (WARN_ON_ONCE(!st->should_run)) return; cpuhp_lock_acquire(bringup); if (st->single) { state = st->cb_state; st->should_run = false; } else { if (bringup) { st->state++; state = st->state; st->should_run = (st->state < st->target); WARN_ON_ONCE(st->state > st->target); } else { state = st->state; st->state--; st->should_run = (st->state > st->target); WARN_ON_ONCE(st->state < st->target); } } WARN_ON_ONCE(!cpuhp_is_ap_state(state)); if (st->rollback) { struct cpuhp_step *step = cpuhp_get_step(state); if (step->skip_onerr) goto next; } if (cpuhp_is_atomic_state(state)) { local_irq_disable(); st->result = cpuhp_invoke_callback(cpu, state, bringup, st->node, &st->last); local_irq_enable(); /* * STARTING/DYING must not fail! */ WARN_ON_ONCE(st->result); } else { st->result = cpuhp_invoke_callback(cpu, state, bringup, st->node, &st->last); } if (st->result) { /* * If we fail on a rollback, we're up a creek without no * paddle, no way forward, no way back. We loose, thanks for * playing. */ WARN_ON_ONCE(st->rollback); st->should_run = false; } next: cpuhp_lock_release(bringup); if (!st->should_run) complete_ap_thread(st, bringup); }

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/* Invoke a single callback on a remote cpu */
static int cpuhp_invoke_ap_callback(int cpu, enum cpuhp_state state, bool bringup, struct hlist_node *node) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); int ret; if (!cpu_online(cpu)) return 0; cpuhp_lock_acquire(false); cpuhp_lock_release(false); cpuhp_lock_acquire(true); cpuhp_lock_release(true); /* * If we are up and running, use the hotplug thread. For early calls * we invoke the thread function directly. */ if (!st->thread) return cpuhp_invoke_callback(cpu, state, bringup, node, NULL); st->rollback = false; st->last = NULL; st->node = node; st->bringup = bringup; st->cb_state = state; st->single = true; __cpuhp_kick_ap(st); /* * If we failed and did a partial, do a rollback. */ if ((ret = st->result) && st->last) { st->rollback = true; st->bringup = !bringup; __cpuhp_kick_ap(st); } /* * Clean up the leftovers so the next hotplug operation wont use stale * data. */ st->node = st->last = NULL; return ret; }

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static int cpuhp_kick_ap_work(unsigned int cpu) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); enum cpuhp_state prev_state = st->state; int ret; cpuhp_lock_acquire(false); cpuhp_lock_release(false); cpuhp_lock_acquire(true); cpuhp_lock_release(true); trace_cpuhp_enter(cpu, st->target, prev_state, cpuhp_kick_ap_work); ret = cpuhp_kick_ap(st, st->target); trace_cpuhp_exit(cpu, st->state, prev_state, ret); return ret; }

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Thomas Gleixner5861.70%360.00%
Peter Zijlstra3638.30%240.00%
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static struct smp_hotplug_thread cpuhp_threads = { .store = &cpuhp_state.thread, .create = &cpuhp_create, .thread_should_run = cpuhp_should_run, .thread_fn = cpuhp_thread_fun, .thread_comm = "cpuhp/%u", .selfparking = true, };
void __init cpuhp_threads_init(void) { BUG_ON(smpboot_register_percpu_thread(&cpuhp_threads)); kthread_unpark(this_cpu_read(cpuhp_state.thread)); }

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Thomas Gleixner27100.00%1100.00%
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#ifdef CONFIG_HOTPLUG_CPU /** * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU * @cpu: a CPU id * * This function walks all processes, finds a valid mm struct for each one and * then clears a corresponding bit in mm's cpumask. While this all sounds * trivial, there are various non-obvious corner cases, which this function * tries to solve in a safe manner. * * Also note that the function uses a somewhat relaxed locking scheme, so it may * be called only for an already offlined CPU. */
void clear_tasks_mm_cpumask(int cpu) { struct task_struct *p; /* * This function is called after the cpu is taken down and marked * offline, so its not like new tasks will ever get this cpu set in * their mm mask. -- Peter Zijlstra * Thus, we may use rcu_read_lock() here, instead of grabbing * full-fledged tasklist_lock. */ WARN_ON(cpu_online(cpu)); rcu_read_lock(); for_each_process(p) { struct task_struct *t; /* * Main thread might exit, but other threads may still have * a valid mm. Find one. */ t = find_lock_task_mm(p); if (!t) continue; cpumask_clear_cpu(cpu, mm_cpumask(t->mm)); task_unlock(t); } rcu_read_unlock(); }

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Anton Vorontsov70100.00%2100.00%
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/* Take this CPU down. */
static int take_cpu_down(void *_param) { struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE); int err, cpu = smp_processor_id(); int ret; /* Ensure this CPU doesn't handle any more interrupts. */ err = __cpu_disable(); if (err < 0) return err; /* * We get here while we are in CPUHP_TEARDOWN_CPU state and we must not * do this step again. */ WARN_ON(st->state != CPUHP_TEARDOWN_CPU); st->state--; /* Invoke the former CPU_DYING callbacks */ for (; st->state > target; st->state--) { ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL); /* * DYING must not fail! */ WARN_ON_ONCE(ret); } /* Give up timekeeping duties */ tick_handover_do_timer(); /* Park the stopper thread */ stop_machine_park(cpu); return 0; }

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Thomas Gleixner11688.55%466.67%
Peter Zijlstra1511.45%233.33%
Total131100.00%6100.00%


static int takedown_cpu(unsigned int cpu) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); int err; /* Park the smpboot threads */ kthread_park(per_cpu_ptr(&cpuhp_state, cpu)->thread); smpboot_park_threads(cpu); /* * Prevent irq alloc/free while the dying cpu reorganizes the * interrupt affinities. */ irq_lock_sparse(); /* * So now all preempt/rcu users must observe !cpu_active(). */ err = stop_machine_cpuslocked(take_cpu_down, NULL, cpumask_of(cpu)); if (err) { /* CPU refused to die */ irq_unlock_sparse(); /* Unpark the hotplug thread so we can rollback there */ kthread_unpark(per_cpu_ptr(&cpuhp_state, cpu)->thread); return err; } BUG_ON(cpu_online(cpu)); /* * The teardown callback for CPUHP_AP_SCHED_STARTING will have removed * all runnable tasks from the CPU, there's only the idle task left now * that the migration thread is done doing the stop_machine thing. * * Wait for the stop thread to go away. */ wait_for_ap_thread(st, false); BUG_ON(st->state != CPUHP_AP_IDLE_DEAD); /* Interrupts are moved away from the dying cpu, reenable alloc/free */ irq_unlock_sparse(); hotplug_cpu__broadcast_tick_pull(cpu); /* This actually kills the CPU. */ __cpu_die(cpu); tick_cleanup_dead_cpu(cpu); rcutree_migrate_callbacks(cpu); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner7451.39%735.00%
Rusty Russell3524.31%420.00%
Sebastian Andrzej Siewior149.72%210.00%
Paul E. McKenney85.56%210.00%
Preeti U. Murthy53.47%15.00%
Peter Zijlstra42.78%210.00%
Nicholas Piggin32.08%15.00%
Brendan Jackman10.69%15.00%
Total144100.00%20100.00%


static void cpuhp_complete_idle_dead(void *arg) { struct cpuhp_cpu_state *st = arg; complete_ap_thread(st, false); }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner2187.50%150.00%
Peter Zijlstra312.50%150.00%
Total24100.00%2100.00%


void cpuhp_report_idle_dead(void) { struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); BUG_ON(st->state != CPUHP_AP_OFFLINE); rcu_report_dead(smp_processor_id()); st->state = CPUHP_AP_IDLE_DEAD; /* * We cannot call complete after rcu_report_dead() so we delegate it * to an online cpu. */ smp_call_function_single(cpumask_first(cpu_online_mask), cpuhp_complete_idle_dead, st, 0); }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner54100.00%3100.00%
Total54100.00%3100.00%


static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st) { for (st->state++; st->state < st->target; st->state++) { struct cpuhp_step *step = cpuhp_get_step(st->state); if (!step->skip_onerr) cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL); } }

Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra71100.00%1100.00%
Total71100.00%1100.00%


static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, enum cpuhp_state target) { enum cpuhp_state prev_state = st->state; int ret = 0; for (; st->state > target; st->state--) { ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL); if (ret) { st->target = prev_state; undo_cpu_down(cpu, st); break; } } return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra88100.00%1100.00%
Total88100.00%1100.00%

/* Requires cpu_add_remove_lock to be held */
static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, enum cpuhp_state target) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); int prev_state, ret = 0; if (num_online_cpus() == 1) return -EBUSY; if (!cpu_present(cpu)) return -EINVAL; cpus_write_lock(); cpuhp_tasks_frozen = tasks_frozen; prev_state = cpuhp_set_state(st, target); /* * If the current CPU state is in the range of the AP hotplug thread, * then we need to kick the thread. */ if (st->state > CPUHP_TEARDOWN_CPU) { st->target = max((int)target, CPUHP_TEARDOWN_CPU); ret = cpuhp_kick_ap_work(cpu); /* * The AP side has done the error rollback already. Just * return the error code.. */ if (ret) goto out; /* * We might have stopped still in the range of the AP hotplug * thread. Nothing to do anymore. */ if (st->state > CPUHP_TEARDOWN_CPU) goto out; st->target = target; } /* * The AP brought itself down to CPUHP_TEARDOWN_CPU. So we need * to do the further cleanups. */ ret = cpuhp_down_callbacks(cpu, st, target); if (ret && st->state > CPUHP_TEARDOWN_CPU && st->state < prev_state) { cpuhp_reset_state(st, prev_state); __cpuhp_kick_ap(st); } out: cpus_write_unlock(); /* * Do post unplug cleanup. This is still protected against * concurrent CPU hotplug via cpu_add_remove_lock. */ lockup_detector_cleanup(); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner13068.78%969.23%
Peter Zijlstra3015.87%17.69%
Sebastian Andrzej Siewior2412.70%17.69%
Rafael J. Wysocki31.59%17.69%
Gautham R. Shenoy21.06%17.69%
Total189100.00%13100.00%


static int do_cpu_down(unsigned int cpu, enum cpuhp_state target) { int err; cpu_maps_update_begin(); if (cpu_hotplug_disabled) { err = -EBUSY; goto out; } err = _cpu_down(cpu, 0, target); out: cpu_maps_update_done(); return err; }

Contributors

PersonTokensPropCommitsCommitProp
Rafael J. Wysocki2954.72%233.33%
Thomas Gleixner815.09%116.67%
Maksim Krasnyanskiy713.21%116.67%
Rusty Russell59.43%116.67%
Gautham R. Shenoy47.55%116.67%
Total53100.00%6100.00%


int cpu_down(unsigned int cpu) { return do_cpu_down(cpu, CPUHP_OFFLINE); }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner17100.00%1100.00%
Total17100.00%1100.00%

EXPORT_SYMBOL(cpu_down); #else #define takedown_cpu NULL #endif /*CONFIG_HOTPLUG_CPU*/ /** * notify_cpu_starting(cpu) - Invoke the callbacks on the starting CPU * @cpu: cpu that just started * * It must be called by the arch code on the new cpu, before the new cpu * enables interrupts and before the "boot" cpu returns from __cpu_up(). */
void notify_cpu_starting(unsigned int cpu) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE); int ret; rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */ while (st->state < target) { st->state++; ret = cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL); /* * STARTING must not fail! */ WARN_ON_ONCE(ret); } }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner6677.65%342.86%
Peter Zijlstra1315.29%228.57%
Paul E. McKenney55.88%114.29%
Sebastian Andrzej Siewior11.18%114.29%
Total85100.00%7100.00%

/* * Called from the idle task. Wake up the controlling task which brings the * stopper and the hotplug thread of the upcoming CPU up and then delegates * the rest of the online bringup to the hotplug thread. */
void cpuhp_online_idle(enum cpuhp_state state) { struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); /* Happens for the boot cpu */ if (state != CPUHP_AP_ONLINE_IDLE) return; st->state = CPUHP_AP_ONLINE_IDLE; complete_ap_thread(st, true); }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner3892.68%375.00%
Peter Zijlstra37.32%125.00%
Total41100.00%4100.00%

/* Requires cpu_add_remove_lock to be held */
static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); struct task_struct *idle; int ret = 0; cpus_write_lock(); if (!cpu_present(cpu)) { ret = -EINVAL; goto out; } /* * The caller of do_cpu_up might have raced with another * caller. Ignore it for now. */ if (st->state >= target) goto out; if (st->state == CPUHP_OFFLINE) { /* Let it fail before we try to bring the cpu up */ idle = idle_thread_get(cpu); if (IS_ERR(idle)) { ret = PTR_ERR(idle); goto out; } } cpuhp_tasks_frozen = tasks_frozen; cpuhp_set_state(st, target); /* * If the current CPU state is in the range of the AP hotplug thread, * then we need to kick the thread once more. */ if (st->state > CPUHP_BRINGUP_CPU) { ret = cpuhp_kick_ap_work(cpu); /* * The AP side has done the error rollback already. Just * return the error code.. */ if (ret) goto out; } /* * Try to reach the target state. We max out on the BP at * CPUHP_BRINGUP_CPU. After that the AP hotplug thread is * responsible for bringing it up to the target state. */ target = min((int)target, CPUHP_BRINGUP_CPU); ret = cpuhp_up_callbacks(cpu, st, target); out: cpus_write_unlock(); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner11162.01%1050.00%
Rusty Russell1910.61%15.00%
Suresh B. Siddha158.38%15.00%
Yasuaki Ishimatsu95.03%15.00%
Rafael J. Wysocki95.03%210.00%
Andrew Morton73.91%210.00%
Gautham R. Shenoy52.79%210.00%
Peter Zijlstra42.23%15.00%
Total179100.00%20100.00%


static int do_cpu_up(unsigned int cpu, enum cpuhp_state target) { int err = 0; if (!cpu_possible(cpu)) { pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n", cpu); #if defined(CONFIG_IA64) pr_err("please check additional_cpus= boot parameter\n"); #endif return -EINVAL; } err = try_online_node(cpu_to_node(cpu)); if (err) return err; cpu_maps_update_begin(); if (cpu_hotplug_disabled) { err = -EBUSY; goto out; } err = _cpu_up(cpu, 0, target); out: cpu_maps_update_done(); return err; }

Contributors

PersonTokensPropCommitsCommitProp
Rafael J. Wysocki3633.96%220.00%
Kamezawa Hiroyuki2927.36%110.00%
Minskey Guo1413.21%110.00%
Thomas Gleixner87.55%110.00%
Maksim Krasnyanskiy76.60%110.00%
Gautham R. Shenoy43.77%110.00%
Fabian Frederick43.77%110.00%
Toshi Kani32.83%110.00%
Rusty Russell10.94%110.00%
Total106100.00%10100.00%


int cpu_up(unsigned int cpu) { return do_cpu_up(cpu, CPUHP_ONLINE); }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner17100.00%1100.00%
Total17100.00%1100.00%

EXPORT_SYMBOL_GPL(cpu_up); #ifdef CONFIG_PM_SLEEP_SMP static cpumask_var_t frozen_cpus;
int freeze_secondary_cpus(int primary) { int cpu, error = 0; cpu_maps_update_begin(); if (!cpu_online(primary)) primary = cpumask_first(cpu_online_mask); /* * We take down all of the non-boot CPUs in one shot to avoid races * with the userspace trying to use the CPU hotplug at the same time */ cpumask_clear(frozen_cpus); pr_info("Disabling non-boot CPUs ...\n"); for_each_online_cpu(cpu) { if (cpu == primary) continue; trace_suspend_resume(TPS("CPU_OFF"), cpu, true); error = _cpu_down(cpu, 1, CPUHP_OFFLINE); trace_suspend_resume(TPS("CPU_OFF"), cpu, false); if (!error) cpumask_set_cpu(cpu, frozen_cpus); else { pr_err("Error taking CPU%d down: %d\n", cpu, error); break; } } if (!error) BUG_ON(num_online_cpus() > 1); else pr_err("Non-boot CPUs are not disabled\n"); /* * Make sure the CPUs won't be enabled by someone else. We need to do * this even in case of failure as all disable_nonboot_cpus() users are * supposed to do enable_nonboot_cpus() on the failure path. */ cpu_hotplug_disabled++; cpu_maps_update_done(); return error; }

Contributors

PersonTokensPropCommitsCommitProp
Rafael J. Wysocki8658.90%323.08%
Todd E Brandt2416.44%17.69%
James Morse138.90%17.69%
Rusty Russell85.48%215.38%
Gautham R. Shenoy42.74%17.69%
Vitaly Kuznetsov42.74%17.69%
Fabian Frederick32.05%17.69%
Thomas Gleixner21.37%17.69%
Ingo Molnar10.68%17.69%
Xiaotian Feng10.68%17.69%
Total146100.00%13100.00%


void __weak arch_enable_nonboot_cpus_begin(void) { }

Contributors

PersonTokensPropCommitsCommitProp
Suresh B. Siddha7100.00%1100.00%
Total7100.00%1100.00%


void __weak arch_enable_nonboot_cpus_end(void) { }

Contributors

PersonTokensPropCommitsCommitProp
Suresh B. Siddha7100.00%1100.00%
Total7100.00%1100.00%


void enable_nonboot_cpus(void) { int cpu, error; /* Allow everyone to use the CPU hotplug again */ cpu_maps_update_begin(); __cpu_hotplug_enable(); if (cpumask_empty(frozen_cpus)) goto out; pr_info("Enabling non-boot CPUs ...\n"); arch_enable_nonboot_cpus_begin(); for_each_cpu(cpu, frozen_cpus) { trace_suspend_resume(TPS("CPU_ON"), cpu, true); error = _cpu_up(cpu, 1, CPUHP_ONLINE); trace_suspend_resume(TPS("CPU_ON"), cpu, false); if (!error) { pr_info("CPU%d is up\n", cpu); continue; } pr_warn("Error taking CPU%d up: %d\n", cpu, error); } arch_enable_nonboot_cpus_end(); cpumask_clear(frozen_cpus); out: cpu_maps_update_done(); }

Contributors

PersonTokensPropCommitsCommitProp
Rafael J. Wysocki7362.39%436.36%
Todd E Brandt2420.51%19.09%
Suresh B. Siddha65.13%19.09%
Gautham R. Shenoy43.42%19.09%
Rusty Russell32.56%19.09%
Fabian Frederick32.56%19.09%
Thomas Gleixner21.71%19.09%
Lianwei Wang21.71%19.09%
Total117100.00%11100.00%


static int __init alloc_frozen_cpus(void) { if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO)) return -ENOMEM; return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Rusty Russell2896.55%150.00%
Fenghua Yu13.45%150.00%
Total29100.00%2100.00%

core_initcall(alloc_frozen_cpus); /* * When callbacks for CPU hotplug notifications are being executed, we must * ensure that the state of the system with respect to the tasks being frozen * or not, as reported by the notification, remains unchanged *throughout the * duration* of the execution of the callbacks. * Hence we need to prevent the freezer from racing with regular CPU hotplug. * * This synchronization is implemented by mutually excluding regular CPU * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/ * Hibernate notifications. */
static int cpu_hotplug_pm_callback(struct notifier_block *nb, unsigned long action, void *ptr) { switch (action) { case PM_SUSPEND_PREPARE: case PM_HIBERNATION_PREPARE: cpu_hotplug_disable(); break; case PM_POST_SUSPEND: case PM_POST_HIBERNATION: cpu_hotplug_enable(); break; default: return NOTIFY_DONE; } return NOTIFY_OK; }

Contributors

PersonTokensPropCommitsCommitProp
Srivatsa S. Bhat52100.00%2100.00%
Total52100.00%2100.00%


static int __init cpu_hotplug_pm_sync_init(void) { /* * cpu_hotplug_pm_callback has higher priority than x86 * bsp_pm_callback which depends on cpu_hotplug_pm_callback * to disable cpu hotplug to avoid cpu hotplug race. */ pm_notifier(cpu_hotplug_pm_callback, 0); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Srivatsa S. Bhat1785.00%133.33%
Fenghua Yu315.00%266.67%
Total20100.00%3100.00%

core_initcall(cpu_hotplug_pm_sync_init); #endif /* CONFIG_PM_SLEEP_SMP */ int __boot_cpu_id; #endif /* CONFIG_SMP */ /* Boot processor state steps */ static struct cpuhp_step cpuhp_hp_states[] = { [CPUHP_OFFLINE] = { .name = "offline", .startup.single = NULL, .teardown.single = NULL, }, #ifdef CONFIG_SMP [CPUHP_CREATE_THREADS]= { .name = "threads:prepare", .startup.single = smpboot_create_threads, .teardown.single = NULL, .cant_stop = true, }, [CPUHP_PERF_PREPARE] = { .name = "perf:prepare", .startup.single = perf_event_init_cpu, .teardown.single = perf_event_exit_cpu, }, [CPUHP_WORKQUEUE_PREP] = { .name = "workqueue:prepare", .startup.single = workqueue_prepare_cpu, .teardown.single = NULL, }, [CPUHP_HRTIMERS_PREPARE] = { .name = "hrtimers:prepare", .startup.single = hrtimers_prepare_cpu, .teardown.single = hrtimers_dead_cpu, }, [CPUHP_SMPCFD_PREPARE] = { .name = "smpcfd:prepare", .startup.single = smpcfd_prepare_cpu, .teardown.single = smpcfd_dead_cpu, }, [CPUHP_RELAY_PREPARE] = { .name = "relay:prepare", .startup.single = relay_prepare_cpu, .teardown.single = NULL, }, [CPUHP_SLAB_PREPARE] = { .name = "slab:prepare", .startup.single = slab_prepare_cpu, .teardown.single = slab_dead_cpu, }, [CPUHP_RCUTREE_PREP] = { .name = "RCU/tree:prepare", .startup.single = rcutree_prepare_cpu, .teardown.single = rcutree_dead_cpu, }, /* * On the tear-down path, timers_dead_cpu() must be invoked * before blk_mq_queue_reinit_notify() from notify_dead(), * otherwise a RCU stall occurs. */ [CPUHP_TIMERS_PREPARE] = { .name = "timers:dead", .startup.single = timers_prepare_cpu, .teardown.single = timers_dead_cpu, }, /* Kicks the plugged cpu into life */ [CPUHP_BRINGUP_CPU] = { .name = "cpu:bringup", .startup.single = bringup_cpu, .teardown.single = NULL, .cant_stop = true, }, /* Final state before CPU kills itself */ [CPUHP_AP_IDLE_DEAD] = { .name = "idle:dead", }, /* * Last state before CPU enters the idle loop to die. Transient state * for synchronization. */ [CPUHP_AP_OFFLINE] = { .name = "ap:offline", .cant_stop = true, }, /* First state is scheduler control. Interrupts are disabled */ [CPUHP_AP_SCHED_STARTING] = { .name = "sched:starting", .startup.single = sched_cpu_starting, .teardown.single = sched_cpu_dying, }, [CPUHP_AP_RCUTREE_DYING] = { .name = "RCU/tree:dying", .startup.single = NULL, .teardown.single = rcutree_dying_cpu, }, [CPUHP_AP_SMPCFD_DYING] = { .name = "smpcfd:dying", .startup.single = NULL, .teardown.single = smpcfd_dying_cpu, }, /* Entry state on starting. Interrupts enabled from here on. Transient * state for synchronsization */ [CPUHP_AP_ONLINE] = { .name = "ap:online", }, /* * Handled on controll processor until the plugged processor manages * this itself. */ [CPUHP_TEARDOWN_CPU] = { .name = "cpu:teardown", .startup.single = NULL, .teardown.single = takedown_cpu, .cant_stop = true, }, /* Handle smpboot threads park/unpark */ [CPUHP_AP_SMPBOOT_THREADS] = { .name = "smpboot/threads:online", .startup.single = smpboot_unpark_threads, .teardown.single = NULL, }, [CPUHP_AP_IRQ_AFFINITY_ONLINE] = { .name = "irq/affinity:online", .startup.single = irq_affinity_online_cpu, .teardown.single = NULL, }, [CPUHP_AP_PERF_ONLINE] = { .name = "perf:online", .startup.single = perf_event_init_cpu, .teardown.single = perf_event_exit_cpu, }, [CPUHP_AP_WORKQUEUE_ONLINE] = { .name = "workqueue:online", .startup.single = workqueue_online_cpu, .teardown.single = workqueue_offline_cpu, }, [CPUHP_AP_RCUTREE_ONLINE] = { .name = "RCU/tree:online", .startup.single = rcutree_online_cpu, .teardown.single = rcutree_offline_cpu, }, #endif /* * The dynamically registered state space is here */ #ifdef CONFIG_SMP /* Last state is scheduler control setting the cpu active */ [CPUHP_AP_ACTIVE] = { .name = "sched:active", .startup.single = sched_cpu_activate, .teardown.single = sched_cpu_deactivate, }, #endif /* CPU is fully up and running. */ [CPUHP_ONLINE] = { .name = "online", .startup.single = NULL, .teardown.single = NULL, }, }; /* Sanity check for callbacks */
static int cpuhp_cb_check(enum cpuhp_state state) { if (state <= CPUHP_OFFLINE || state >= CPUHP_ONLINE) return -EINVAL; return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner27100.00%2100.00%
Total27100.00%2100.00%

/* * Returns a free for dynamic slot assignment of the Online state. The states * are protected by the cpuhp_slot_states mutex and an empty slot is identified * by having no name assigned. */
static int cpuhp_reserve_state(enum cpuhp_state state) { enum cpuhp_state i, end; struct cpuhp_step *step; switch (state) { case CPUHP_AP_ONLINE_DYN: step = cpuhp_hp_states + CPUHP_AP_ONLINE_DYN; end = CPUHP_AP_ONLINE_DYN_END; break; case CPUHP_BP_PREPARE_DYN: step = cpuhp_hp_states + CPUHP_BP_PREPARE_DYN; end = CPUHP_BP_PREPARE_DYN_END; break; default: return -EINVAL; } for (i = state; i <= end; i++, step++) { if (!step->name) return i; } WARN(1, "No more dynamic states available for CPU hotplug\n"); return -ENOSPC; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner9797.98%266.67%
Lai Jiangshan22.02%133.33%
Total99100.00%3100.00%


static int cpuhp_store_callbacks(enum cpuhp_state state, const char *name, int (*startup)(unsigned int cpu), int (*teardown)(unsigned int cpu), bool multi_instance) { /* (Un)Install the callbacks for further cpu hotplug operations */ struct cpuhp_step *sp; int ret = 0; /* * If name is NULL, then the state gets removed. * * CPUHP_AP_ONLINE_DYN and CPUHP_BP_PREPARE_DYN are handed out on * the first allocation from these dynamic ranges, so the removal * would trigger a new allocation and clear the wrong (already * empty) state, leaving the callbacks of the to be cleared state * dangling, which causes wreckage on the next hotplug operation. */ if (name && (state == CPUHP_AP_ONLINE_DYN || state == CPUHP_BP_PREPARE_DYN)) { ret = cpuhp_reserve_state(state); if (ret < 0) return ret; state = ret; } sp = cpuhp_get_step(state); if (name && sp->name) return -EBUSY; sp->startup.single = startup; sp->teardown.single = teardown; sp->name = name; sp->multi_instance = multi_instance; INIT_HLIST_HEAD(&sp->list); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner13693.15%571.43%
Ethan Barnes53.42%114.29%
Sebastian Andrzej Siewior53.42%114.29%
Total146100.00%7100.00%


static void *cpuhp_get_teardown_cb(enum cpuhp_state state) { return cpuhp_get_step(state)->teardown.single; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner21100.00%2100.00%
Total21100.00%2100.00%

/* * Call the startup/teardown function for a step either on the AP or * on the current CPU. */
static int cpuhp_issue_call(int cpu, enum cpuhp_state state, bool bringup, struct hlist_node *node) { struct cpuhp_step *sp = cpuhp_get_step(state); int ret; /* * If there's nothing to do, we done. * Relies on the union for multi_instance. */ if ((bringup && !sp->startup.single) || (!bringup && !sp->teardown.single)) return 0; /* * The non AP bound callbacks can fail on bringup. On teardown * e.g. module removal we crash for now. */ #ifdef CONFIG_SMP if (cpuhp_is_ap_state(state)) ret = cpuhp_invoke_ap_callback(cpu, state, bringup, node); else ret = cpuhp_invoke_callback(cpu, state, bringup, node, NULL); #else ret = cpuhp_invoke_callback(cpu, state, bringup, node, NULL); #endif BUG_ON(ret && !bringup); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner12896.24%571.43%
Peter Zijlstra53.76%228.57%
Total133100.00%7100.00%

/* * Called from __cpuhp_setup_state on a recoverable failure. * * Note: The teardown callbacks for rollback are not allowed to fail! */
static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state, struct hlist_node *node) { int cpu; /* Roll back the already executed steps on the other cpus */ for_each_present_cpu(cpu) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); int cpustate = st->state; if (cpu >= failedcpu) break; /* Did we invoke the startup call on that cpu ? */ if (cpustate >= state) cpuhp_issue_call(cpu, state, false, node); } }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner73100.00%2100.00%
Total73100.00%2100.00%


int __cpuhp_state_add_instance_cpuslocked(enum cpuhp_state state, struct hlist_node *node, bool invoke) { struct cpuhp_step *sp; int cpu; int ret; lockdep_assert_cpus_held(); sp = cpuhp_get_step(state); if (sp->multi_instance == false) return -EINVAL; mutex_lock(&cpuhp_state_mutex); if (!invoke || !sp->startup.multi) goto add_node; /* * Try to call the startup callback for each present cpu * depending on the hotplug state of the cpu. */ for_each_present_cpu(cpu) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); int cpustate = st->state; if (cpustate < state) continue; ret = cpuhp_issue_call(cpu, state, true, node); if (ret) { if (sp->teardown.multi) cpuhp_rollback_install(cpu, state, node); goto unlock; } } add_node: ret = 0; hlist_add_head(node, &sp->list); unlock: mutex_unlock(&cpuhp_state_mutex); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner16294.74%480.00%
Sebastian Andrzej Siewior95.26%120.00%
Total171100.00%5100.00%


int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node, bool invoke) { int ret; cpus_read_lock(); ret = __cpuhp_state_add_instance_cpuslocked(state, node, invoke); cpus_read_unlock(); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner40100.00%4100.00%
Total40100.00%4100.00%

EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance); /** * __cpuhp_setup_state_cpuslocked - Setup the callbacks for an hotplug machine state * @state: The state to setup * @invoke: If true, the startup function is invoked for cpus where * cpu state >= @state * @startup: startup callback function * @teardown: teardown callback function * @multi_instance: State is set up for multiple instances which get * added afterwards. * * The caller needs to hold cpus read locked while calling this function. * Returns: * On success: * Positive state number if @state is CPUHP_AP_ONLINE_DYN * 0 for all other states * On failure: proper (negative) error code */
int __cpuhp_setup_state_cpuslocked(enum cpuhp_state state, const char *name, bool invoke, int (*startup)(unsigned int cpu), int (*teardown)(unsigned int cpu), bool multi_instance) { int cpu, ret = 0; bool dynstate; lockdep_assert_cpus_held(); if (cpuhp_cb_check(state) || !name) return -EINVAL; mutex_lock(&cpuhp_state_mutex); ret = cpuhp_store_callbacks(state, name, startup, teardown, multi_instance); dynstate = state == CPUHP_AP_ONLINE_DYN; if (ret > 0 && dynstate) { state = ret; ret = 0; } if (ret || !invoke || !startup) goto out; /* * Try to call the startup callback for each present cpu * depending on the hotplug state of the cpu. */ for_each_present_cpu(cpu) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); int cpustate = st->state; if (cpustate < state) continue; ret = cpuhp_issue_call(cpu, state, true, NULL); if (ret) { if (teardown) cpuhp_rollback_install(cpu, state, NULL); cpuhp_store_callbacks(state, NULL, NULL, NULL, false); goto out; } } out: mutex_unlock(&cpuhp_state_mutex); /* * If the requested state is CPUHP_AP_ONLINE_DYN, return the * dynamically allocated state in case of success. */ if (!ret && dynstate) return state; return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner21593.07%571.43%
Sebastian Andrzej Siewior166.93%228.57%
Total231100.00%7100.00%

EXPORT_SYMBOL(__cpuhp_setup_state_cpuslocked);
int __cpuhp_setup_state(enum cpuhp_state state, const char *name, bool invoke, int (*startup)(unsigned int cpu), int (*teardown)(unsigned int cpu), bool multi_instance) { int ret; cpus_read_lock(); ret = __cpuhp_setup_state_cpuslocked(state, name, invoke, startup, teardown, multi_instance); cpus_read_unlock(); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Sebastian Andrzej Siewior71100.00%1100.00%
Total71100.00%1100.00%

EXPORT_SYMBOL(__cpuhp_setup_state);
int __cpuhp_state_remove_instance(enum cpuhp_state state, struct hlist_node *node, bool invoke) { struct cpuhp_step *sp = cpuhp_get_step(state); int cpu; BUG_ON(cpuhp_cb_check(state)); if (!sp->multi_instance) return -EINVAL; cpus_read_lock(); mutex_lock(&cpuhp_state_mutex); if (!invoke || !cpuhp_get_teardown_cb(state)) goto remove; /* * Call the teardown callback for each present cpu depending * on the hotplug state of the cpu. This function is not * allowed to fail currently! */ for_each_present_cpu(cpu) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); int cpustate = st->state; if (cpustate >= state) cpuhp_issue_call(cpu, state, false, node); } remove: hlist_del(node); mutex_unlock(&cpuhp_state_mutex); cpus_read_unlock(); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner12995.56%266.67%
Sebastian Andrzej Siewior64.44%133.33%
Total135100.00%3100.00%

EXPORT_SYMBOL_GPL(__cpuhp_state_remove_instance); /** * __cpuhp_remove_state_cpuslocked - Remove the callbacks for an hotplug machine state * @state: The state to remove * @invoke: If true, the teardown function is invoked for cpus where * cpu state >= @state * * The caller needs to hold cpus read locked while calling this function. * The teardown callback is currently not allowed to fail. Think * about module removal! */
void __cpuhp_remove_state_cpuslocked(enum cpuhp_state state, bool invoke) { struct cpuhp_step *sp = cpuhp_get_step(state); int cpu; BUG_ON(cpuhp_cb_check(state)); lockdep_assert_cpus_held(); mutex_lock(&cpuhp_state_mutex); if (sp->multi_instance) { WARN(!hlist_empty(&sp->list), "Error: Removing state %d which has instances left.\n", state); goto remove; } if (!invoke || !cpuhp_get_teardown_cb(state)) goto remove; /* * Call the teardown callback for each present cpu depending * on the hotplug state of the cpu. This function is not * allowed to fail currently! */ for_each_present_cpu(cpu) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); int cpustate = st->state; if (cpustate >= state) cpuhp_issue_call(cpu, state, false, NULL); } remove: cpuhp_store_callbacks(state, NULL, NULL, NULL, false); mutex_unlock(&cpuhp_state_mutex); }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner13389.86%360.00%
Sebastian Andrzej Siewior1510.14%240.00%
Total148100.00%5100.00%

EXPORT_SYMBOL(__cpuhp_remove_state_cpuslocked);
void __cpuhp_remove_state(enum cpuhp_state state, bool invoke) { cpus_read_lock(); __cpuhp_remove_state_cpuslocked(state, invoke); cpus_read_unlock(); }

Contributors

PersonTokensPropCommitsCommitProp
Sebastian Andrzej Siewior2184.00%133.33%
Thomas Gleixner416.00%266.67%
Total25100.00%3100.00%

EXPORT_SYMBOL(__cpuhp_remove_state); #if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)
static ssize_t show_cpuhp_state(struct device *dev, struct device_attribute *attr, char *buf) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id); return sprintf(buf, "%d\n", st->state); }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner47100.00%1100.00%
Total47100.00%1100.00%

static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL);
static ssize_t write_cpuhp_target(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id); struct cpuhp_step *sp; int target, ret; ret = kstrtoint(buf, 10, &target); if (ret) return ret; #ifdef CONFIG_CPU_HOTPLUG_STATE_CONTROL if (target < CPUHP_OFFLINE || target > CPUHP_ONLINE) return -EINVAL; #else if (target != CPUHP_OFFLINE && target != CPUHP_ONLINE) return -EINVAL; #endif ret = lock_device_hotplug_sysfs(); if (ret) return ret; mutex_lock(&cpuhp_state_mutex); sp = cpuhp_get_step(target); ret = !sp->name || sp->cant_stop ? -EINVAL : 0; mutex_unlock(&cpuhp_state_mutex); if (ret) goto out; if (st->state < target) ret = do_cpu_up(dev->id, target); else ret = do_cpu_down(dev->id, target); out: unlock_device_hotplug(); return ret ? ret : count; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner19597.50%150.00%
Sebastian Andrzej Siewior52.50%150.00%
Total200100.00%2100.00%


static ssize_t show_cpuhp_target(struct device *dev, struct device_attribute *attr, char *buf) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id); return sprintf(buf, "%d\n", st->target); }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner47100.00%1100.00%
Total47100.00%1100.00%

static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target);
static ssize_t write_cpuhp_fail(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id); struct cpuhp_step *sp; int fail, ret; ret = kstrtoint(buf, 10, &fail); if (ret) return ret; /* * Cannot fail STARTING/DYING callbacks. */ if (cpuhp_is_atomic_state(fail)) return -EINVAL; /* * Cannot fail anything that doesn't have callbacks. */ mutex_lock(&cpuhp_state_mutex); sp = cpuhp_get_step(fail); if (!sp->startup.single && !sp->teardown.single) ret = -EINVAL; mutex_unlock(&cpuhp_state_mutex); if (ret) return ret; st->fail = fail; return count; }

Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra137100.00%1100.00%
Total137100.00%1100.00%


static ssize_t show_cpuhp_fail(struct device *dev, struct device_attribute *attr, char *buf) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id); return sprintf(buf, "%d\n", st->fail); }

Contributors

PersonTokensPropCommitsCommitProp
Peter Zijlstra47100.00%1100.00%
Total47100.00%1100.00%

static DEVICE_ATTR(fail, 0644, show_cpuhp_fail, write_cpuhp_fail); static struct attribute *cpuhp_cpu_attrs[] = { &dev_attr_state.attr, &dev_attr_target.attr, &dev_attr_fail.attr, NULL }; static const struct attribute_group cpuhp_cpu_attr_group = { .attrs = cpuhp_cpu_attrs, .name = "hotplug", NULL };
static ssize_t show_cpuhp_states(struct device *dev, struct device_attribute *attr, char *buf) { ssize_t cur, res = 0; int i; mutex_lock(&cpuhp_state_mutex); for (i = CPUHP_OFFLINE; i <= CPUHP_ONLINE; i++) { struct cpuhp_step *sp = cpuhp_get_step(i); if (sp->name) { cur = sprintf(buf, "%3d: %s\n", i, sp->name); buf += cur; res += cur; } } mutex_unlock(&cpuhp_state_mutex); return res; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner101100.00%2100.00%
Total101100.00%2100.00%

static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL); static struct attribute *cpuhp_cpu_root_attrs[] = { &dev_attr_states.attr, NULL }; static const struct attribute_group cpuhp_cpu_root_attr_group = { .attrs = cpuhp_cpu_root_attrs, .name = "hotplug", NULL };
static int __init cpuhp_sysfs_init(void) { int cpu, ret; ret = sysfs_create_group(&cpu_subsys.dev_root->kobj, &cpuhp_cpu_root_attr_group); if (ret) return ret; for_each_possible_cpu(cpu) { struct device *dev = get_cpu_device(cpu); if (!dev) continue; ret = sysfs_create_group(&dev->kobj, &cpuhp_cpu_attr_group); if (ret) return ret; } return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner81100.00%1100.00%
Total81100.00%1100.00%

device_initcall(cpuhp_sysfs_init); #endif /* * cpu_bit_bitmap[] is a special, "compressed" data structure that * represents all NR_CPUS bits binary values of 1<<nr. * * It is used by cpumask_of() to get a constant address to a CPU * mask value that has a single bit set only. */ /* cpu_bit_bitmap[0] is empty - so we can back into it */ #define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x)) #define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1) #define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2) #define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4) const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = { MASK_DECLARE_8(0), MASK_DECLARE_8(8), MASK_DECLARE_8(16), MASK_DECLARE_8(24), #if BITS_PER_LONG > 32 MASK_DECLARE_8(32), MASK_DECLARE_8(40), MASK_DECLARE_8(48), MASK_DECLARE_8(56), #endif }; EXPORT_SYMBOL_GPL(cpu_bit_bitmap); const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL; EXPORT_SYMBOL(cpu_all_bits); #ifdef CONFIG_INIT_ALL_POSSIBLE struct cpumask __cpu_possible_mask __read_mostly = {CPU_BITS_ALL}; #else struct cpumask __cpu_possible_mask __read_mostly; #endif EXPORT_SYMBOL(__cpu_possible_mask); struct cpumask __cpu_online_mask __read_mostly; EXPORT_SYMBOL(__cpu_online_mask); struct cpumask __cpu_present_mask __read_mostly; EXPORT_SYMBOL(__cpu_present_mask); struct cpumask __cpu_active_mask __read_mostly; EXPORT_SYMBOL(__cpu_active_mask);
void init_cpu_present(const struct cpumask *src) { cpumask_copy(&__cpu_present_mask, src); }

Contributors

PersonTokensPropCommitsCommitProp
Rusty Russell1789.47%150.00%
Rasmus Villemoes210.53%150.00%
Total19100.00%2100.00%


void init_cpu_possible(const struct cpumask *src) { cpumask_copy(&__cpu_possible_mask, src); }

Contributors

PersonTokensPropCommitsCommitProp
Rusty Russell1789.47%150.00%
Rasmus Villemoes210.53%150.00%
Total19100.00%2100.00%


void init_cpu_online(const struct cpumask *src) { cpumask_copy(&__cpu_online_mask, src); }

Contributors

PersonTokensPropCommitsCommitProp
Rusty Russell1789.47%150.00%
Rasmus Villemoes210.53%150.00%
Total19100.00%2100.00%

/* * Activate the first processor. */
void __init boot_cpu_init(void) { int cpu = smp_processor_id(); /* Mark the boot cpu "present", "online" etc for SMP and UP case */ set_cpu_online(cpu, true); set_cpu_active(cpu, true); set_cpu_present(cpu, true); set_cpu_possible(cpu, true); #ifdef CONFIG_SMP __boot_cpu_id = cpu; #endif }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner4382.69%150.00%
Peter Zijlstra917.31%150.00%
Total52100.00%2100.00%

/* * Must be called _AFTER_ setting up the per_cpu areas */
void __init boot_cpu_hotplug_init(void) { per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE; }

Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner2095.24%150.00%
Linus Torvalds14.76%150.00%
Total21100.00%2100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
Thomas Gleixner427359.07%5033.11%
Peter Zijlstra133618.47%85.30%
Rafael J. Wysocki2503.46%63.97%
Sebastian Andrzej Siewior2493.44%74.64%
Rusty Russell2223.07%106.62%
Srivatsa S. Bhat1081.49%21.32%
Lai Jiangshan921.27%31.99%
Anton Vorontsov801.11%21.32%
Mike Travis580.80%10.66%
Todd E Brandt510.71%10.66%
Gautham R. Shenoy490.68%31.99%
Rasmus Villemoes490.68%21.32%
Richard Weinberger480.66%21.32%
Linus Torvalds440.61%42.65%
Suresh B. Siddha350.48%21.32%
Kamezawa Hiroyuki290.40%10.66%
Lianwei Wang260.36%10.66%
Paul E. McKenney210.29%63.97%
Richard Cochran200.28%21.32%
Ashok Raj200.28%21.32%
Arnd Bergmann200.28%10.66%
Maksim Krasnyanskiy170.24%21.32%
Vitaly Kuznetsov150.21%21.32%
Ingo Molnar140.19%63.97%
Minskey Guo140.19%10.66%
James Morse130.18%10.66%
Fabian Frederick100.14%10.66%
Yasuaki Ishimatsu90.12%10.66%
Preeti U. Murthy80.11%10.66%
Andrew Morton70.10%21.32%
David Hildenbrand70.10%10.66%
Rui Zhang50.07%10.66%
Ethan Barnes50.07%10.66%
Fenghua Yu40.06%21.32%
Toshi Kani40.06%21.32%
Mathieu Malaterre40.06%10.66%
Nicholas Piggin30.04%10.66%
Michal Hocko30.04%10.66%
Tejun Heo30.04%10.66%
Arvind Yadav20.03%10.66%
Joonas Lahtinen20.03%10.66%
Michael Rodriguez10.01%10.66%
Xiaotian Feng10.01%10.66%
Boris Ostrovsky10.01%10.66%
Paul Gortmaker10.01%10.66%
Brendan Jackman10.01%10.66%
Total7234100.00%151100.00%
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