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1931 lines
47 KiB
1931 lines
47 KiB
/* CPU control. |
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* (C) 2001, 2002, 2003, 2004 Rusty Russell |
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* |
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* This code is licenced under the GPL. |
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*/ |
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#include <linux/proc_fs.h> |
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#include <linux/smp.h> |
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#include <linux/init.h> |
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#include <linux/notifier.h> |
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#include <linux/sched.h> |
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#include <linux/unistd.h> |
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#include <linux/cpu.h> |
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#include <linux/oom.h> |
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#include <linux/rcupdate.h> |
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#include <linux/export.h> |
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#include <linux/bug.h> |
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#include <linux/kthread.h> |
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#include <linux/stop_machine.h> |
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#include <linux/mutex.h> |
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#include <linux/gfp.h> |
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#include <linux/suspend.h> |
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#include <linux/lockdep.h> |
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#include <linux/tick.h> |
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#include <linux/irq.h> |
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#include <linux/smpboot.h> |
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#include <linux/relay.h> |
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#include <linux/slab.h> |
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|
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#include <trace/events/power.h> |
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#define CREATE_TRACE_POINTS |
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#include <trace/events/cpuhp.h> |
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|
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#include "smpboot.h" |
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|
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/** |
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* cpuhp_cpu_state - Per cpu hotplug state storage |
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* @state: The current cpu state |
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* @target: The target state |
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* @thread: Pointer to the hotplug thread |
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* @should_run: Thread should execute |
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* @rollback: Perform a rollback |
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* @single: Single callback invocation |
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* @bringup: Single callback bringup or teardown selector |
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* @cb_state: The state for a single callback (install/uninstall) |
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* @result: Result of the operation |
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* @done: Signal completion to the issuer of the task |
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*/ |
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struct cpuhp_cpu_state { |
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enum cpuhp_state state; |
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enum cpuhp_state target; |
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#ifdef CONFIG_SMP |
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struct task_struct *thread; |
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bool should_run; |
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bool rollback; |
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bool single; |
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bool bringup; |
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struct hlist_node *node; |
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enum cpuhp_state cb_state; |
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int result; |
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struct completion done; |
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#endif |
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}; |
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|
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static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state); |
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|
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/** |
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* cpuhp_step - Hotplug state machine step |
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* @name: Name of the step |
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* @startup: Startup function of the step |
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* @teardown: Teardown function of the step |
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* @skip_onerr: Do not invoke the functions on error rollback |
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* Will go away once the notifiers are gone |
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* @cant_stop: Bringup/teardown can't be stopped at this step |
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*/ |
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struct cpuhp_step { |
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const char *name; |
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union cpuhp_step_startup startup; |
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union cpuhp_step_teardown teardown; |
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struct hlist_head list; |
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bool skip_onerr; |
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bool cant_stop; |
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bool multi_instance; |
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}; |
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|
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static DEFINE_MUTEX(cpuhp_state_mutex); |
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static struct cpuhp_step cpuhp_bp_states[]; |
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static struct cpuhp_step cpuhp_ap_states[]; |
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|
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static bool cpuhp_is_ap_state(enum cpuhp_state state) |
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{ |
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/* |
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* The extra check for CPUHP_TEARDOWN_CPU is only for documentation |
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* purposes as that state is handled explicitly in cpu_down. |
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*/ |
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return state > CPUHP_BRINGUP_CPU && state != CPUHP_TEARDOWN_CPU; |
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} |
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|
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static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state) |
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{ |
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struct cpuhp_step *sp; |
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|
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sp = cpuhp_is_ap_state(state) ? cpuhp_ap_states : cpuhp_bp_states; |
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return sp + state; |
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} |
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|
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/** |
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* cpuhp_invoke_callback _ Invoke the callbacks for a given state |
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* @cpu: The cpu for which the callback should be invoked |
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* @step: The step in the state machine |
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* @bringup: True if the bringup callback should be invoked |
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* |
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* Called from cpu hotplug and from the state register machinery. |
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*/ |
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static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state, |
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bool bringup, struct hlist_node *node) |
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{ |
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struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
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struct cpuhp_step *step = cpuhp_get_step(state); |
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int (*cbm)(unsigned int cpu, struct hlist_node *node); |
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int (*cb)(unsigned int cpu); |
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int ret, cnt; |
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|
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if (!step->multi_instance) { |
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cb = bringup ? step->startup.single : step->teardown.single; |
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if (!cb) |
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return 0; |
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trace_cpuhp_enter(cpu, st->target, state, cb); |
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ret = cb(cpu); |
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trace_cpuhp_exit(cpu, st->state, state, ret); |
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return ret; |
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} |
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cbm = bringup ? step->startup.multi : step->teardown.multi; |
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if (!cbm) |
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return 0; |
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|
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/* Single invocation for instance add/remove */ |
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if (node) { |
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trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node); |
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ret = cbm(cpu, node); |
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trace_cpuhp_exit(cpu, st->state, state, ret); |
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return ret; |
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} |
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|
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/* State transition. Invoke on all instances */ |
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cnt = 0; |
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hlist_for_each(node, &step->list) { |
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trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node); |
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ret = cbm(cpu, node); |
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trace_cpuhp_exit(cpu, st->state, state, ret); |
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if (ret) |
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goto err; |
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cnt++; |
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} |
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return 0; |
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err: |
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/* Rollback the instances if one failed */ |
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cbm = !bringup ? step->startup.multi : step->teardown.multi; |
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if (!cbm) |
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return ret; |
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hlist_for_each(node, &step->list) { |
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if (!cnt--) |
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break; |
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cbm(cpu, node); |
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} |
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return ret; |
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} |
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#ifdef CONFIG_SMP |
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/* Serializes the updates to cpu_online_mask, cpu_present_mask */ |
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static DEFINE_MUTEX(cpu_add_remove_lock); |
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bool cpuhp_tasks_frozen; |
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EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen); |
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|
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/* |
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* The following two APIs (cpu_maps_update_begin/done) must be used when |
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* attempting to serialize the updates to cpu_online_mask & cpu_present_mask. |
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* The APIs cpu_notifier_register_begin/done() must be used to protect CPU |
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* hotplug callback (un)registration performed using __register_cpu_notifier() |
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* or __unregister_cpu_notifier(). |
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*/ |
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void cpu_maps_update_begin(void) |
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{ |
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mutex_lock(&cpu_add_remove_lock); |
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} |
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EXPORT_SYMBOL(cpu_notifier_register_begin); |
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void cpu_maps_update_done(void) |
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{ |
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mutex_unlock(&cpu_add_remove_lock); |
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} |
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EXPORT_SYMBOL(cpu_notifier_register_done); |
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static RAW_NOTIFIER_HEAD(cpu_chain); |
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|
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/* If set, cpu_up and cpu_down will return -EBUSY and do nothing. |
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* Should always be manipulated under cpu_add_remove_lock |
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*/ |
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static int cpu_hotplug_disabled; |
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#ifdef CONFIG_HOTPLUG_CPU |
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static struct { |
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struct task_struct *active_writer; |
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/* wait queue to wake up the active_writer */ |
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wait_queue_head_t wq; |
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/* verifies that no writer will get active while readers are active */ |
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struct mutex lock; |
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/* |
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* Also blocks the new readers during |
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* an ongoing cpu hotplug operation. |
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*/ |
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atomic_t refcount; |
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#ifdef CONFIG_DEBUG_LOCK_ALLOC |
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struct lockdep_map dep_map; |
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#endif |
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} cpu_hotplug = { |
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.active_writer = NULL, |
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.wq = __WAIT_QUEUE_HEAD_INITIALIZER(cpu_hotplug.wq), |
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.lock = __MUTEX_INITIALIZER(cpu_hotplug.lock), |
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#ifdef CONFIG_DEBUG_LOCK_ALLOC |
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.dep_map = STATIC_LOCKDEP_MAP_INIT("cpu_hotplug.dep_map", &cpu_hotplug.dep_map), |
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#endif |
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}; |
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/* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */ |
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#define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map) |
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#define cpuhp_lock_acquire_tryread() \ |
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lock_map_acquire_tryread(&cpu_hotplug.dep_map) |
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#define cpuhp_lock_acquire() lock_map_acquire(&cpu_hotplug.dep_map) |
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#define cpuhp_lock_release() lock_map_release(&cpu_hotplug.dep_map) |
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void get_online_cpus(void) |
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{ |
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might_sleep(); |
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if (cpu_hotplug.active_writer == current) |
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return; |
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cpuhp_lock_acquire_read(); |
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mutex_lock(&cpu_hotplug.lock); |
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atomic_inc(&cpu_hotplug.refcount); |
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mutex_unlock(&cpu_hotplug.lock); |
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} |
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EXPORT_SYMBOL_GPL(get_online_cpus); |
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void put_online_cpus(void) |
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{ |
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int refcount; |
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if (cpu_hotplug.active_writer == current) |
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return; |
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refcount = atomic_dec_return(&cpu_hotplug.refcount); |
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if (WARN_ON(refcount < 0)) /* try to fix things up */ |
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atomic_inc(&cpu_hotplug.refcount); |
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if (refcount <= 0 && waitqueue_active(&cpu_hotplug.wq)) |
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wake_up(&cpu_hotplug.wq); |
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cpuhp_lock_release(); |
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} |
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EXPORT_SYMBOL_GPL(put_online_cpus); |
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/* |
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* This ensures that the hotplug operation can begin only when the |
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* refcount goes to zero. |
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* |
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* Note that during a cpu-hotplug operation, the new readers, if any, |
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* will be blocked by the cpu_hotplug.lock |
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* |
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* Since cpu_hotplug_begin() is always called after invoking |
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* cpu_maps_update_begin(), we can be sure that only one writer is active. |
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* |
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* Note that theoretically, there is a possibility of a livelock: |
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* - Refcount goes to zero, last reader wakes up the sleeping |
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* writer. |
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* - Last reader unlocks the cpu_hotplug.lock. |
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* - A new reader arrives at this moment, bumps up the refcount. |
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* - The writer acquires the cpu_hotplug.lock finds the refcount |
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* non zero and goes to sleep again. |
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* |
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* However, this is very difficult to achieve in practice since |
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* get_online_cpus() not an api which is called all that often. |
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* |
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*/ |
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void cpu_hotplug_begin(void) |
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{ |
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DEFINE_WAIT(wait); |
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cpu_hotplug.active_writer = current; |
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cpuhp_lock_acquire(); |
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for (;;) { |
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mutex_lock(&cpu_hotplug.lock); |
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prepare_to_wait(&cpu_hotplug.wq, &wait, TASK_UNINTERRUPTIBLE); |
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if (likely(!atomic_read(&cpu_hotplug.refcount))) |
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break; |
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mutex_unlock(&cpu_hotplug.lock); |
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schedule(); |
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} |
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finish_wait(&cpu_hotplug.wq, &wait); |
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} |
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void cpu_hotplug_done(void) |
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{ |
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cpu_hotplug.active_writer = NULL; |
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mutex_unlock(&cpu_hotplug.lock); |
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cpuhp_lock_release(); |
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} |
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|
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/* |
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* Wait for currently running CPU hotplug operations to complete (if any) and |
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* disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects |
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* the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the |
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* hotplug path before performing hotplug operations. So acquiring that lock |
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* guarantees mutual exclusion from any currently running hotplug operations. |
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*/ |
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void cpu_hotplug_disable(void) |
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{ |
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cpu_maps_update_begin(); |
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cpu_hotplug_disabled++; |
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cpu_maps_update_done(); |
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} |
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EXPORT_SYMBOL_GPL(cpu_hotplug_disable); |
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static void __cpu_hotplug_enable(void) |
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{ |
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if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n")) |
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return; |
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cpu_hotplug_disabled--; |
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} |
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void cpu_hotplug_enable(void) |
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{ |
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cpu_maps_update_begin(); |
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__cpu_hotplug_enable(); |
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cpu_maps_update_done(); |
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} |
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EXPORT_SYMBOL_GPL(cpu_hotplug_enable); |
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#endif /* CONFIG_HOTPLUG_CPU */ |
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|
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/* Need to know about CPUs going up/down? */ |
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int register_cpu_notifier(struct notifier_block *nb) |
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{ |
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int ret; |
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cpu_maps_update_begin(); |
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ret = raw_notifier_chain_register(&cpu_chain, nb); |
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cpu_maps_update_done(); |
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return ret; |
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} |
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|
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int __register_cpu_notifier(struct notifier_block *nb) |
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{ |
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return raw_notifier_chain_register(&cpu_chain, nb); |
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} |
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|
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static int __cpu_notify(unsigned long val, unsigned int cpu, int nr_to_call, |
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int *nr_calls) |
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{ |
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unsigned long mod = cpuhp_tasks_frozen ? CPU_TASKS_FROZEN : 0; |
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void *hcpu = (void *)(long)cpu; |
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int ret; |
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ret = __raw_notifier_call_chain(&cpu_chain, val | mod, hcpu, nr_to_call, |
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nr_calls); |
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return notifier_to_errno(ret); |
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} |
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static int cpu_notify(unsigned long val, unsigned int cpu) |
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{ |
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return __cpu_notify(val, cpu, -1, NULL); |
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} |
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static void cpu_notify_nofail(unsigned long val, unsigned int cpu) |
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{ |
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BUG_ON(cpu_notify(val, cpu)); |
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} |
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|
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/* Notifier wrappers for transitioning to state machine */ |
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static int notify_prepare(unsigned int cpu) |
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{ |
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int nr_calls = 0; |
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int ret; |
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|
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ret = __cpu_notify(CPU_UP_PREPARE, cpu, -1, &nr_calls); |
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if (ret) { |
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nr_calls--; |
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printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n", |
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__func__, cpu); |
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__cpu_notify(CPU_UP_CANCELED, cpu, nr_calls, NULL); |
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} |
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return ret; |
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} |
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|
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static int notify_online(unsigned int cpu) |
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{ |
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cpu_notify(CPU_ONLINE, cpu); |
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return 0; |
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} |
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|
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static int bringup_wait_for_ap(unsigned int cpu) |
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{ |
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struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
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|
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wait_for_completion(&st->done); |
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return st->result; |
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} |
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|
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static int bringup_cpu(unsigned int cpu) |
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{ |
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struct task_struct *idle = idle_thread_get(cpu); |
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int ret; |
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|
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/* |
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* Some architectures have to walk the irq descriptors to |
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* setup the vector space for the cpu which comes online. |
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* Prevent irq alloc/free across the bringup. |
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*/ |
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irq_lock_sparse(); |
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|
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/* Arch-specific enabling code. */ |
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ret = __cpu_up(cpu, idle); |
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irq_unlock_sparse(); |
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if (ret) { |
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cpu_notify(CPU_UP_CANCELED, cpu); |
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return ret; |
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} |
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ret = bringup_wait_for_ap(cpu); |
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BUG_ON(!cpu_online(cpu)); |
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return ret; |
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} |
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|
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/* |
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* Hotplug state machine related functions |
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*/ |
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static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st) |
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{ |
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for (st->state++; st->state < st->target; st->state++) { |
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struct cpuhp_step *step = cpuhp_get_step(st->state); |
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|
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if (!step->skip_onerr) |
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cpuhp_invoke_callback(cpu, st->state, true, NULL); |
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} |
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} |
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|
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static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, |
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enum cpuhp_state target) |
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{ |
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enum cpuhp_state prev_state = st->state; |
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int ret = 0; |
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|
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for (; st->state > target; st->state--) { |
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ret = cpuhp_invoke_callback(cpu, st->state, false, NULL); |
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if (ret) { |
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st->target = prev_state; |
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undo_cpu_down(cpu, st); |
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break; |
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} |
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} |
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return ret; |
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} |
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|
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static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st) |
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{ |
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for (st->state--; st->state > st->target; st->state--) { |
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struct cpuhp_step *step = cpuhp_get_step(st->state); |
|
|
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if (!step->skip_onerr) |
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cpuhp_invoke_callback(cpu, st->state, false, NULL); |
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} |
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} |
|
|
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static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, |
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enum cpuhp_state target) |
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{ |
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enum cpuhp_state prev_state = st->state; |
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int ret = 0; |
|
|
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while (st->state < target) { |
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st->state++; |
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ret = cpuhp_invoke_callback(cpu, st->state, true, NULL); |
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if (ret) { |
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st->target = prev_state; |
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undo_cpu_up(cpu, st); |
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break; |
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} |
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} |
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return ret; |
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} |
|
|
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/* |
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* The cpu hotplug threads manage the bringup and teardown of the cpus |
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*/ |
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static void cpuhp_create(unsigned int cpu) |
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{ |
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struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
|
|
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init_completion(&st->done); |
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} |
|
|
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static int cpuhp_should_run(unsigned int cpu) |
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{ |
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struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); |
|
|
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return st->should_run; |
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} |
|
|
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/* Execute the teardown callbacks. Used to be CPU_DOWN_PREPARE */ |
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static int cpuhp_ap_offline(unsigned int cpu, struct cpuhp_cpu_state *st) |
|
{ |
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enum cpuhp_state target = max((int)st->target, CPUHP_TEARDOWN_CPU); |
|
|
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return cpuhp_down_callbacks(cpu, st, target); |
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} |
|
|
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/* Execute the online startup callbacks. Used to be CPU_ONLINE */ |
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static int cpuhp_ap_online(unsigned int cpu, struct cpuhp_cpu_state *st) |
|
{ |
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return cpuhp_up_callbacks(cpu, st, st->target); |
|
} |
|
|
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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. |
|
*/ |
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static void cpuhp_thread_fun(unsigned int cpu) |
|
{ |
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struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); |
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int ret = 0; |
|
|
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/* |
|
* Paired with the mb() in cpuhp_kick_ap_work and |
|
* cpuhp_invoke_ap_callback, so the work set is consistent visible. |
|
*/ |
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smp_mb(); |
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if (!st->should_run) |
|
return; |
|
|
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st->should_run = false; |
|
|
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/* Single callback invocation for [un]install ? */ |
|
if (st->single) { |
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if (st->cb_state < CPUHP_AP_ONLINE) { |
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local_irq_disable(); |
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ret = cpuhp_invoke_callback(cpu, st->cb_state, |
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st->bringup, st->node); |
|
local_irq_enable(); |
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} else { |
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ret = cpuhp_invoke_callback(cpu, st->cb_state, |
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st->bringup, st->node); |
|
} |
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} else if (st->rollback) { |
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BUG_ON(st->state < CPUHP_AP_ONLINE_IDLE); |
|
|
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undo_cpu_down(cpu, st); |
|
/* |
|
* This is a momentary workaround to keep the notifier users |
|
* happy. Will go away once we got rid of the notifiers. |
|
*/ |
|
cpu_notify_nofail(CPU_DOWN_FAILED, cpu); |
|
st->rollback = false; |
|
} else { |
|
/* Cannot happen .... */ |
|
BUG_ON(st->state < CPUHP_AP_ONLINE_IDLE); |
|
|
|
/* Regular hotplug work */ |
|
if (st->state < st->target) |
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ret = cpuhp_ap_online(cpu, st); |
|
else if (st->state > st->target) |
|
ret = cpuhp_ap_offline(cpu, st); |
|
} |
|
st->result = ret; |
|
complete(&st->done); |
|
} |
|
|
|
/* 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); |
|
|
|
if (!cpu_online(cpu)) |
|
return 0; |
|
|
|
/* |
|
* 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); |
|
|
|
st->cb_state = state; |
|
st->single = true; |
|
st->bringup = bringup; |
|
st->node = node; |
|
|
|
/* |
|
* 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_completion(&st->done); |
|
return st->result; |
|
} |
|
|
|
/* Regular hotplug invocation of the AP hotplug thread */ |
|
static void __cpuhp_kick_ap_work(struct cpuhp_cpu_state *st) |
|
{ |
|
st->result = 0; |
|
st->single = false; |
|
/* |
|
* 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); |
|
} |
|
|
|
static int cpuhp_kick_ap_work(unsigned int cpu) |
|
{ |
|
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); |
|
enum cpuhp_state state = st->state; |
|
|
|
trace_cpuhp_enter(cpu, st->target, state, cpuhp_kick_ap_work); |
|
__cpuhp_kick_ap_work(st); |
|
wait_for_completion(&st->done); |
|
trace_cpuhp_exit(cpu, st->state, state, st->result); |
|
return st->result; |
|
} |
|
|
|
static struct smp_hotplug_thread cpuhp_threads __read_only = { |
|
.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)); |
|
} |
|
|
|
EXPORT_SYMBOL(register_cpu_notifier); |
|
EXPORT_SYMBOL(__register_cpu_notifier); |
|
void unregister_cpu_notifier(struct notifier_block *nb) |
|
{ |
|
cpu_maps_update_begin(); |
|
raw_notifier_chain_unregister(&cpu_chain, nb); |
|
cpu_maps_update_done(); |
|
} |
|
EXPORT_SYMBOL(unregister_cpu_notifier); |
|
|
|
void __unregister_cpu_notifier(struct notifier_block *nb) |
|
{ |
|
raw_notifier_chain_unregister(&cpu_chain, nb); |
|
} |
|
EXPORT_SYMBOL(__unregister_cpu_notifier); |
|
|
|
#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(); |
|
} |
|
|
|
static inline void check_for_tasks(int dead_cpu) |
|
{ |
|
struct task_struct *g, *p; |
|
|
|
read_lock(&tasklist_lock); |
|
for_each_process_thread(g, p) { |
|
if (!p->on_rq) |
|
continue; |
|
/* |
|
* We do the check with unlocked task_rq(p)->lock. |
|
* Order the reading to do not warn about a task, |
|
* which was running on this cpu in the past, and |
|
* it's just been woken on another cpu. |
|
*/ |
|
rmb(); |
|
if (task_cpu(p) != dead_cpu) |
|
continue; |
|
|
|
pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n", |
|
p->comm, task_pid_nr(p), dead_cpu, p->state, p->flags); |
|
} |
|
read_unlock(&tasklist_lock); |
|
} |
|
|
|
static int notify_down_prepare(unsigned int cpu) |
|
{ |
|
int err, nr_calls = 0; |
|
|
|
err = __cpu_notify(CPU_DOWN_PREPARE, cpu, -1, &nr_calls); |
|
if (err) { |
|
nr_calls--; |
|
__cpu_notify(CPU_DOWN_FAILED, cpu, nr_calls, NULL); |
|
pr_warn("%s: attempt to take down CPU %u failed\n", |
|
__func__, cpu); |
|
} |
|
return err; |
|
} |
|
|
|
/* 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(); |
|
|
|
/* 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--) |
|
cpuhp_invoke_callback(cpu, st->state, false, NULL); |
|
|
|
/* Give up timekeeping duties */ |
|
tick_handover_do_timer(); |
|
/* Park the stopper thread */ |
|
stop_machine_park(cpu); |
|
return 0; |
|
} |
|
|
|
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(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 CPUHP_AP_SCHED_MIGRATE_DYING callback 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_completion(&st->done); |
|
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); |
|
return 0; |
|
} |
|
|
|
static int notify_dead(unsigned int cpu) |
|
{ |
|
cpu_notify_nofail(CPU_DEAD, cpu); |
|
check_for_tasks(cpu); |
|
return 0; |
|
} |
|
|
|
static void cpuhp_complete_idle_dead(void *arg) |
|
{ |
|
struct cpuhp_cpu_state *st = arg; |
|
|
|
complete(&st->done); |
|
} |
|
|
|
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); |
|
} |
|
|
|
#else |
|
#define notify_down_prepare NULL |
|
#define takedown_cpu NULL |
|
#define notify_dead NULL |
|
#endif |
|
|
|
#ifdef CONFIG_HOTPLUG_CPU |
|
|
|
/* 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; |
|
bool hasdied = false; |
|
|
|
if (num_online_cpus() == 1) |
|
return -EBUSY; |
|
|
|
if (!cpu_present(cpu)) |
|
return -EINVAL; |
|
|
|
cpu_hotplug_begin(); |
|
|
|
cpuhp_tasks_frozen = tasks_frozen; |
|
|
|
prev_state = st->state; |
|
st->target = 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) { |
|
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; |
|
} |
|
/* |
|
* 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) { |
|
st->target = prev_state; |
|
st->rollback = true; |
|
cpuhp_kick_ap_work(cpu); |
|
} |
|
|
|
hasdied = prev_state != st->state && st->state == CPUHP_OFFLINE; |
|
out: |
|
cpu_hotplug_done(); |
|
/* This post dead nonsense must die */ |
|
if (!ret && hasdied) |
|
cpu_notify_nofail(CPU_POST_DEAD, cpu); |
|
return ret; |
|
} |
|
|
|
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; |
|
} |
|
int cpu_down(unsigned int cpu) |
|
{ |
|
return do_cpu_down(cpu, CPUHP_OFFLINE); |
|
} |
|
EXPORT_SYMBOL(cpu_down); |
|
#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); |
|
|
|
rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */ |
|
while (st->state < target) { |
|
st->state++; |
|
cpuhp_invoke_callback(cpu, st->state, true, NULL); |
|
} |
|
} |
|
|
|
/* |
|
* Called from the idle task. We need to set active here, so we can kick off |
|
* the stopper thread and unpark the smpboot threads. If the target state is |
|
* beyond CPUHP_AP_ONLINE_IDLE we kick cpuhp thread and let it bring up the |
|
* cpu further. |
|
*/ |
|
void cpuhp_online_idle(enum cpuhp_state state) |
|
{ |
|
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); |
|
unsigned int cpu = smp_processor_id(); |
|
|
|
/* Happens for the boot cpu */ |
|
if (state != CPUHP_AP_ONLINE_IDLE) |
|
return; |
|
|
|
st->state = CPUHP_AP_ONLINE_IDLE; |
|
|
|
/* Unpark the stopper thread and the hotplug thread of this cpu */ |
|
stop_machine_unpark(cpu); |
|
kthread_unpark(st->thread); |
|
|
|
/* Should we go further up ? */ |
|
if (st->target > CPUHP_AP_ONLINE_IDLE) |
|
__cpuhp_kick_ap_work(st); |
|
else |
|
complete(&st->done); |
|
} |
|
|
|
/* 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; |
|
|
|
cpu_hotplug_begin(); |
|
|
|
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; |
|
|
|
st->target = 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: |
|
cpu_hotplug_done(); |
|
return ret; |
|
} |
|
|
|
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; |
|
} |
|
|
|
int cpu_up(unsigned int cpu) |
|
{ |
|
return do_cpu_up(cpu, CPUHP_ONLINE); |
|
} |
|
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; |
|
} |
|
|
|
void __weak arch_enable_nonboot_cpus_begin(void) |
|
{ |
|
} |
|
|
|
void __weak arch_enable_nonboot_cpus_end(void) |
|
{ |
|
} |
|
|
|
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(); |
|
} |
|
|
|
static int __init alloc_frozen_cpus(void) |
|
{ |
|
if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO)) |
|
return -ENOMEM; |
|
return 0; |
|
} |
|
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; |
|
} |
|
|
|
|
|
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; |
|
} |
|
core_initcall(cpu_hotplug_pm_sync_init); |
|
|
|
#endif /* CONFIG_PM_SLEEP_SMP */ |
|
|
|
#endif /* CONFIG_SMP */ |
|
|
|
/* Boot processor state steps */ |
|
static struct cpuhp_step cpuhp_bp_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, |
|
}, |
|
/* |
|
* Preparatory and dead notifiers. Will be replaced once the notifiers |
|
* are converted to states. |
|
*/ |
|
[CPUHP_NOTIFY_PREPARE] = { |
|
.name = "notify:prepare", |
|
.startup.single = notify_prepare, |
|
.teardown.single = notify_dead, |
|
.skip_onerr = true, |
|
.cant_stop = true, |
|
}, |
|
/* |
|
* 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_DEAD] = { |
|
.name = "timers:dead", |
|
.startup.single = NULL, |
|
.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, |
|
}, |
|
[CPUHP_AP_SMPCFD_DYING] = { |
|
.name = "smpcfd:dying", |
|
.startup.single = NULL, |
|
.teardown.single = smpcfd_dying_cpu, |
|
}, |
|
/* |
|
* 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, |
|
}, |
|
#else |
|
[CPUHP_BRINGUP_CPU] = { }, |
|
#endif |
|
}; |
|
|
|
/* Application processor state steps */ |
|
static struct cpuhp_step cpuhp_ap_states[] = { |
|
#ifdef CONFIG_SMP |
|
/* 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, |
|
}, |
|
/* Entry state on starting. Interrupts enabled from here on. Transient |
|
* state for synchronsization */ |
|
[CPUHP_AP_ONLINE] = { |
|
.name = "ap:online", |
|
}, |
|
/* Handle smpboot threads park/unpark */ |
|
[CPUHP_AP_SMPBOOT_THREADS] = { |
|
.name = "smpboot/threads:online", |
|
.startup.single = smpboot_unpark_threads, |
|
.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, |
|
}, |
|
|
|
/* |
|
* Online/down_prepare notifiers. Will be removed once the notifiers |
|
* are converted to states. |
|
*/ |
|
[CPUHP_AP_NOTIFY_ONLINE] = { |
|
.name = "notify:online", |
|
.startup.single = notify_online, |
|
.teardown.single = notify_down_prepare, |
|
.skip_onerr = true, |
|
}, |
|
#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; |
|
} |
|
|
|
static void cpuhp_store_callbacks(enum cpuhp_state state, |
|
const char *name, |
|
union cpuhp_step_startup startup, |
|
union cpuhp_step_teardown teardown, |
|
bool multi_instance) |
|
{ |
|
/* (Un)Install the callbacks for further cpu hotplug operations */ |
|
struct cpuhp_step *sp; |
|
|
|
mutex_lock(&cpuhp_state_mutex); |
|
sp = cpuhp_get_step(state); |
|
sp->startup = startup; |
|
sp->teardown = teardown; |
|
sp->name = name; |
|
sp->multi_instance = multi_instance; |
|
INIT_HLIST_HEAD(&sp->list); |
|
mutex_unlock(&cpuhp_state_mutex); |
|
} |
|
|
|
static union cpuhp_step_teardown cpuhp_get_teardown_cb(enum cpuhp_state state) |
|
{ |
|
return cpuhp_get_step(state)->teardown; |
|
} |
|
|
|
/* |
|
* 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 ((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); |
|
#else |
|
ret = cpuhp_invoke_callback(cpu, state, bringup, node); |
|
#endif |
|
BUG_ON(ret && !bringup); |
|
return ret; |
|
} |
|
|
|
/* |
|
* 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); |
|
} |
|
} |
|
|
|
/* |
|
* 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; |
|
|
|
mutex_lock(&cpuhp_state_mutex); |
|
for (i = CPUHP_AP_ONLINE_DYN; i <= CPUHP_AP_ONLINE_DYN_END; i++) { |
|
if (cpuhp_ap_states[i].name) |
|
continue; |
|
|
|
cpuhp_ap_states[i].name = "Reserved"; |
|
mutex_unlock(&cpuhp_state_mutex); |
|
return i; |
|
} |
|
mutex_unlock(&cpuhp_state_mutex); |
|
WARN(1, "No more dynamic states available for CPU hotplug\n"); |
|
return -ENOSPC; |
|
} |
|
|
|
int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node, |
|
bool invoke) |
|
{ |
|
struct cpuhp_step *sp; |
|
int cpu; |
|
int ret; |
|
|
|
sp = cpuhp_get_step(state); |
|
if (sp->multi_instance == false) |
|
return -EINVAL; |
|
|
|
get_online_cpus(); |
|
|
|
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 err; |
|
} |
|
} |
|
add_node: |
|
ret = 0; |
|
mutex_lock(&cpuhp_state_mutex); |
|
hlist_add_head(node, &sp->list); |
|
mutex_unlock(&cpuhp_state_mutex); |
|
|
|
err: |
|
put_online_cpus(); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance); |
|
|
|
/** |
|
* __cpuhp_setup_state - 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 |
|
* |
|
* Returns 0 if successful, otherwise a proper error code |
|
*/ |
|
int __cpuhp_setup_state(enum cpuhp_state state, |
|
const char *name, bool invoke, |
|
union cpuhp_step_startup startup, |
|
union cpuhp_step_teardown teardown, |
|
bool multi_instance) |
|
{ |
|
int cpu, ret = 0; |
|
int dyn_state = 0; |
|
|
|
if (cpuhp_cb_check(state) || !name) |
|
return -EINVAL; |
|
|
|
get_online_cpus(); |
|
|
|
/* currently assignments for the ONLINE state are possible */ |
|
if (state == CPUHP_AP_ONLINE_DYN) { |
|
dyn_state = 1; |
|
ret = cpuhp_reserve_state(state); |
|
if (ret < 0) |
|
goto out; |
|
state = ret; |
|
} |
|
|
|
cpuhp_store_callbacks(state, name, startup, teardown, multi_instance); |
|
|
|
if (!invoke || (multi_instance ? !startup.multi : !startup.single)) |
|
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) { |
|
union cpuhp_step_startup startup = { .single = NULL }; |
|
union cpuhp_step_teardown teardown = { .single = NULL }; |
|
|
|
if (multi_instance ? !!teardown.multi : !!teardown.single) |
|
cpuhp_rollback_install(cpu, state, NULL); |
|
cpuhp_store_callbacks(state, NULL, startup, teardown, false); |
|
goto out; |
|
} |
|
} |
|
out: |
|
put_online_cpus(); |
|
if (!ret && dyn_state) |
|
return state; |
|
return ret; |
|
} |
|
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; |
|
|
|
get_online_cpus(); |
|
if (!invoke || !cpuhp_get_teardown_cb(state).single) |
|
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: |
|
mutex_lock(&cpuhp_state_mutex); |
|
hlist_del(node); |
|
mutex_unlock(&cpuhp_state_mutex); |
|
put_online_cpus(); |
|
|
|
return 0; |
|
} |
|
EXPORT_SYMBOL_GPL(__cpuhp_state_remove_instance); |
|
/** |
|
* __cpuhp_remove_state - 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 teardown callback is currently not allowed to fail. Think |
|
* about module removal! |
|
*/ |
|
void __cpuhp_remove_state(enum cpuhp_state state, bool invoke) |
|
{ |
|
struct cpuhp_step *sp = cpuhp_get_step(state); |
|
int cpu; |
|
union cpuhp_step_startup startup = { .single = NULL }; |
|
union cpuhp_step_teardown teardown = { .single = NULL }; |
|
|
|
BUG_ON(cpuhp_cb_check(state)); |
|
|
|
get_online_cpus(); |
|
|
|
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).single) |
|
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, startup, teardown, false); |
|
put_online_cpus(); |
|
} |
|
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); |
|
} |
|
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) |
|
return ret; |
|
|
|
if (st->state < target) |
|
ret = do_cpu_up(dev->id, target); |
|
else |
|
ret = do_cpu_down(dev->id, target); |
|
|
|
unlock_device_hotplug(); |
|
return ret ? ret : count; |
|
} |
|
|
|
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); |
|
} |
|
static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target); |
|
|
|
static struct attribute *cpuhp_cpu_attrs[] = { |
|
&dev_attr_state.attr, |
|
&dev_attr_target.attr, |
|
NULL |
|
}; |
|
|
|
static 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; |
|
} |
|
static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL); |
|
|
|
static struct attribute *cpuhp_cpu_root_attrs[] = { |
|
&dev_attr_states.attr, |
|
NULL |
|
}; |
|
|
|
static 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; |
|
} |
|
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); |
|
} |
|
|
|
void init_cpu_possible(const struct cpumask *src) |
|
{ |
|
cpumask_copy(&__cpu_possible_mask, src); |
|
} |
|
|
|
void init_cpu_online(const struct cpumask *src) |
|
{ |
|
cpumask_copy(&__cpu_online_mask, src); |
|
} |
|
|
|
/* |
|
* 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); |
|
} |
|
|
|
/* |
|
* Must be called _AFTER_ setting up the per_cpu areas |
|
*/ |
|
void __init boot_cpu_state_init(void) |
|
{ |
|
per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE; |
|
}
|
|
|