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2705 lines
65 KiB
2705 lines
65 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/sched/mm.h> |
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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/signal.h> |
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#include <linux/sched/hotplug.h> |
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#include <linux/sched/isolation.h> |
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#include <linux/sched/task.h> |
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#include <linux/sched/smt.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/nmi.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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#include <linux/percpu-rwsem.h> |
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#include <linux/cpuset.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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* struct 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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* @fail: Current CPU hotplug callback 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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* @cpu: CPU number |
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* @node: Remote CPU node; for multi-instance, do a |
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* single entry callback for install/remove |
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* @last: For multi-instance rollback, remember how far we got |
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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_up: Signal completion to the issuer of the task for cpu-up |
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* @done_down: Signal completion to the issuer of the task for cpu-down |
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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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enum cpuhp_state fail; |
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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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int cpu; |
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struct hlist_node *node; |
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struct hlist_node *last; |
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enum cpuhp_state cb_state; |
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int result; |
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struct completion done_up; |
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struct completion done_down; |
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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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.fail = CPUHP_INVALID, |
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}; |
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|
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#ifdef CONFIG_SMP |
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cpumask_t cpus_booted_once_mask; |
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#endif |
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#if defined(CONFIG_LOCKDEP) && defined(CONFIG_SMP) |
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static struct lockdep_map cpuhp_state_up_map = |
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STATIC_LOCKDEP_MAP_INIT("cpuhp_state-up", &cpuhp_state_up_map); |
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static struct lockdep_map cpuhp_state_down_map = |
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STATIC_LOCKDEP_MAP_INIT("cpuhp_state-down", &cpuhp_state_down_map); |
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static inline void cpuhp_lock_acquire(bool bringup) |
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{ |
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lock_map_acquire(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map); |
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} |
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|
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static inline void cpuhp_lock_release(bool bringup) |
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{ |
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lock_map_release(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map); |
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} |
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#else |
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|
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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 |
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/** |
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* struct 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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* @cant_stop: Bringup/teardown can't be stopped at this step |
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* @multi_instance: State has multiple instances which get added afterwards |
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*/ |
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struct cpuhp_step { |
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const char *name; |
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union { |
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int (*single)(unsigned int cpu); |
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int (*multi)(unsigned int cpu, |
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struct hlist_node *node); |
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} startup; |
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union { |
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int (*single)(unsigned int cpu); |
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int (*multi)(unsigned int cpu, |
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struct hlist_node *node); |
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} teardown; |
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/* private: */ |
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struct hlist_head list; |
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/* public: */ |
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bool cant_stop; |
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bool multi_instance; |
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}; |
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static DEFINE_MUTEX(cpuhp_state_mutex); |
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static struct cpuhp_step cpuhp_hp_states[]; |
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static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state) |
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{ |
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return cpuhp_hp_states + state; |
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} |
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static bool cpuhp_step_empty(bool bringup, struct cpuhp_step *step) |
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{ |
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return bringup ? !step->startup.single : !step->teardown.single; |
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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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* @state: The state to do callbacks for |
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* @bringup: True if the bringup callback should be invoked |
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* @node: For multi-instance, do a single entry callback for install/remove |
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* @lastp: For multi-instance rollback, remember how far we got |
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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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* Return: %0 on success or a negative errno code |
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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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struct hlist_node **lastp) |
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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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if (st->fail == state) { |
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st->fail = CPUHP_INVALID; |
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return -EAGAIN; |
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} |
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if (cpuhp_step_empty(bringup, step)) { |
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WARN_ON_ONCE(1); |
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return 0; |
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} |
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if (!step->multi_instance) { |
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WARN_ON_ONCE(lastp && *lastp); |
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cb = bringup ? step->startup.single : step->teardown.single; |
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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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|
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/* Single invocation for instance add/remove */ |
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if (node) { |
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WARN_ON_ONCE(lastp && *lastp); |
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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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/* 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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if (lastp && node == *lastp) |
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break; |
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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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if (!lastp) |
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goto err; |
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*lastp = node; |
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return ret; |
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} |
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cnt++; |
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} |
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if (lastp) |
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*lastp = NULL; |
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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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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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/* |
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* Rollback must not fail, |
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*/ |
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WARN_ON_ONCE(ret); |
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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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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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static inline void wait_for_ap_thread(struct cpuhp_cpu_state *st, bool bringup) |
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{ |
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struct completion *done = bringup ? &st->done_up : &st->done_down; |
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wait_for_completion(done); |
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} |
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static inline void complete_ap_thread(struct cpuhp_cpu_state *st, bool bringup) |
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{ |
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struct completion *done = bringup ? &st->done_up : &st->done_down; |
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complete(done); |
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} |
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/* |
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* The former STARTING/DYING states, ran with IRQs disabled and must not fail. |
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*/ |
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static bool cpuhp_is_atomic_state(enum cpuhp_state state) |
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{ |
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return CPUHP_AP_IDLE_DEAD <= state && state < CPUHP_AP_ONLINE; |
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} |
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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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* 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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*/ |
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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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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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/* |
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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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DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock); |
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void cpus_read_lock(void) |
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{ |
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percpu_down_read(&cpu_hotplug_lock); |
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} |
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EXPORT_SYMBOL_GPL(cpus_read_lock); |
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int cpus_read_trylock(void) |
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{ |
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return percpu_down_read_trylock(&cpu_hotplug_lock); |
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} |
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EXPORT_SYMBOL_GPL(cpus_read_trylock); |
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void cpus_read_unlock(void) |
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{ |
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percpu_up_read(&cpu_hotplug_lock); |
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} |
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EXPORT_SYMBOL_GPL(cpus_read_unlock); |
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void cpus_write_lock(void) |
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{ |
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percpu_down_write(&cpu_hotplug_lock); |
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} |
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void cpus_write_unlock(void) |
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{ |
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percpu_up_write(&cpu_hotplug_lock); |
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} |
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void lockdep_assert_cpus_held(void) |
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{ |
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/* |
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* We can't have hotplug operations before userspace starts running, |
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* and some init codepaths will knowingly not take the hotplug lock. |
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* This is all valid, so mute lockdep until it makes sense to report |
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* unheld locks. |
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*/ |
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if (system_state < SYSTEM_RUNNING) |
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return; |
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percpu_rwsem_assert_held(&cpu_hotplug_lock); |
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} |
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#ifdef CONFIG_LOCKDEP |
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int lockdep_is_cpus_held(void) |
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{ |
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return percpu_rwsem_is_held(&cpu_hotplug_lock); |
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} |
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#endif |
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static void lockdep_acquire_cpus_lock(void) |
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{ |
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rwsem_acquire(&cpu_hotplug_lock.dep_map, 0, 0, _THIS_IP_); |
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} |
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static void lockdep_release_cpus_lock(void) |
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{ |
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rwsem_release(&cpu_hotplug_lock.dep_map, _THIS_IP_); |
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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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#else |
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static void lockdep_acquire_cpus_lock(void) |
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{ |
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} |
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static void lockdep_release_cpus_lock(void) |
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{ |
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} |
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#endif /* CONFIG_HOTPLUG_CPU */ |
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/* |
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* Architectures that need SMT-specific errata handling during SMT hotplug |
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* should override this. |
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*/ |
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void __weak arch_smt_update(void) { } |
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#ifdef CONFIG_HOTPLUG_SMT |
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enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED; |
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void __init cpu_smt_disable(bool force) |
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{ |
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if (!cpu_smt_possible()) |
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return; |
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if (force) { |
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pr_info("SMT: Force disabled\n"); |
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cpu_smt_control = CPU_SMT_FORCE_DISABLED; |
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} else { |
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pr_info("SMT: disabled\n"); |
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cpu_smt_control = CPU_SMT_DISABLED; |
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} |
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} |
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/* |
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* The decision whether SMT is supported can only be done after the full |
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* CPU identification. Called from architecture code. |
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*/ |
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void __init cpu_smt_check_topology(void) |
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{ |
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if (!topology_smt_supported()) |
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cpu_smt_control = CPU_SMT_NOT_SUPPORTED; |
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} |
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static int __init smt_cmdline_disable(char *str) |
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{ |
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cpu_smt_disable(str && !strcmp(str, "force")); |
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return 0; |
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} |
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early_param("nosmt", smt_cmdline_disable); |
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static inline bool cpu_smt_allowed(unsigned int cpu) |
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{ |
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if (cpu_smt_control == CPU_SMT_ENABLED) |
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return true; |
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|
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if (topology_is_primary_thread(cpu)) |
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return true; |
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/* |
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* On x86 it's required to boot all logical CPUs at least once so |
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* that the init code can get a chance to set CR4.MCE on each |
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* CPU. Otherwise, a broadcasted MCE observing CR4.MCE=0b on any |
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* core will shutdown the machine. |
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*/ |
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return !cpumask_test_cpu(cpu, &cpus_booted_once_mask); |
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} |
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|
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/* Returns true if SMT is not supported of forcefully (irreversibly) disabled */ |
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bool cpu_smt_possible(void) |
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{ |
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return cpu_smt_control != CPU_SMT_FORCE_DISABLED && |
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cpu_smt_control != CPU_SMT_NOT_SUPPORTED; |
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} |
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EXPORT_SYMBOL_GPL(cpu_smt_possible); |
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#else |
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static inline bool cpu_smt_allowed(unsigned int cpu) { return true; } |
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#endif |
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|
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static inline enum cpuhp_state |
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cpuhp_set_state(struct cpuhp_cpu_state *st, enum cpuhp_state target) |
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{ |
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enum cpuhp_state prev_state = st->state; |
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bool bringup = st->state < target; |
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|
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st->rollback = false; |
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st->last = NULL; |
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|
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st->target = target; |
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st->single = false; |
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st->bringup = bringup; |
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if (cpu_dying(st->cpu) != !bringup) |
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set_cpu_dying(st->cpu, !bringup); |
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|
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return prev_state; |
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} |
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|
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static inline void |
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cpuhp_reset_state(struct cpuhp_cpu_state *st, enum cpuhp_state prev_state) |
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{ |
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bool bringup = !st->bringup; |
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|
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st->target = prev_state; |
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|
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/* |
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* Already rolling back. No need invert the bringup value or to change |
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* the current state. |
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*/ |
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if (st->rollback) |
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return; |
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|
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st->rollback = true; |
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|
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/* |
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* If we have st->last we need to undo partial multi_instance of this |
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* state first. Otherwise start undo at the previous state. |
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*/ |
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if (!st->last) { |
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if (st->bringup) |
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st->state--; |
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else |
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st->state++; |
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} |
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|
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st->bringup = bringup; |
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if (cpu_dying(st->cpu) != !bringup) |
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set_cpu_dying(st->cpu, !bringup); |
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} |
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|
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/* Regular hotplug invocation of the AP hotplug thread */ |
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static void __cpuhp_kick_ap(struct cpuhp_cpu_state *st) |
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{ |
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if (!st->single && st->state == st->target) |
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return; |
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|
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st->result = 0; |
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/* |
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* Make sure the above stores are visible before should_run becomes |
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* true. Paired with the mb() above in cpuhp_thread_fun() |
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*/ |
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smp_mb(); |
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st->should_run = true; |
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wake_up_process(st->thread); |
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wait_for_ap_thread(st, st->bringup); |
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} |
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|
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static int cpuhp_kick_ap(struct cpuhp_cpu_state *st, enum cpuhp_state target) |
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{ |
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enum cpuhp_state prev_state; |
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int ret; |
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|
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prev_state = cpuhp_set_state(st, target); |
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__cpuhp_kick_ap(st); |
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if ((ret = st->result)) { |
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cpuhp_reset_state(st, prev_state); |
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__cpuhp_kick_ap(st); |
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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 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 the CPU to reach CPUHP_AP_ONLINE_IDLE */ |
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wait_for_ap_thread(st, true); |
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if (WARN_ON_ONCE((!cpu_online(cpu)))) |
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return -ECANCELED; |
|
|
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/* Unpark the hotplug thread of the target cpu */ |
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kthread_unpark(st->thread); |
|
|
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/* |
|
* SMT soft disabling on X86 requires to bring the CPU out of the |
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* BIOS 'wait for SIPI' state in order to set the CR4.MCE bit. The |
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* CPU marked itself as booted_once in notify_cpu_starting() so the |
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* cpu_smt_allowed() check will now return false if this is not the |
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* primary sibling. |
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*/ |
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if (!cpu_smt_allowed(cpu)) |
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return -ECANCELED; |
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|
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if (st->target <= CPUHP_AP_ONLINE_IDLE) |
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return 0; |
|
|
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return cpuhp_kick_ap(st, st->target); |
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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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/* |
|
* 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); |
|
} |
|
|
|
static int finish_cpu(unsigned int cpu) |
|
{ |
|
struct task_struct *idle = idle_thread_get(cpu); |
|
struct mm_struct *mm = idle->active_mm; |
|
|
|
/* |
|
* idle_task_exit() will have switched to &init_mm, now |
|
* clean up any remaining active_mm state. |
|
*/ |
|
if (mm != &init_mm) |
|
idle->active_mm = &init_mm; |
|
mmdrop(mm); |
|
return 0; |
|
} |
|
|
|
/* |
|
* Hotplug state machine related functions |
|
*/ |
|
|
|
/* |
|
* Get the next state to run. Empty ones will be skipped. Returns true if a |
|
* state must be run. |
|
* |
|
* st->state will be modified ahead of time, to match state_to_run, as if it |
|
* has already ran. |
|
*/ |
|
static bool cpuhp_next_state(bool bringup, |
|
enum cpuhp_state *state_to_run, |
|
struct cpuhp_cpu_state *st, |
|
enum cpuhp_state target) |
|
{ |
|
do { |
|
if (bringup) { |
|
if (st->state >= target) |
|
return false; |
|
|
|
*state_to_run = ++st->state; |
|
} else { |
|
if (st->state <= target) |
|
return false; |
|
|
|
*state_to_run = st->state--; |
|
} |
|
|
|
if (!cpuhp_step_empty(bringup, cpuhp_get_step(*state_to_run))) |
|
break; |
|
} while (true); |
|
|
|
return true; |
|
} |
|
|
|
static int cpuhp_invoke_callback_range(bool bringup, |
|
unsigned int cpu, |
|
struct cpuhp_cpu_state *st, |
|
enum cpuhp_state target) |
|
{ |
|
enum cpuhp_state state; |
|
int err = 0; |
|
|
|
while (cpuhp_next_state(bringup, &state, st, target)) { |
|
err = cpuhp_invoke_callback(cpu, state, bringup, NULL, NULL); |
|
if (err) |
|
break; |
|
} |
|
|
|
return err; |
|
} |
|
|
|
static inline bool can_rollback_cpu(struct cpuhp_cpu_state *st) |
|
{ |
|
if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) |
|
return true; |
|
/* |
|
* When CPU hotplug is disabled, then taking the CPU down is not |
|
* possible because takedown_cpu() and the architecture and |
|
* subsystem specific mechanisms are not available. So the CPU |
|
* which would be completely unplugged again needs to stay around |
|
* in the current state. |
|
*/ |
|
return st->state <= CPUHP_BRINGUP_CPU; |
|
} |
|
|
|
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; |
|
|
|
ret = cpuhp_invoke_callback_range(true, cpu, st, target); |
|
if (ret) { |
|
pr_debug("CPU UP failed (%d) CPU %u state %s (%d)\n", |
|
ret, cpu, cpuhp_get_step(st->state)->name, |
|
st->state); |
|
|
|
cpuhp_reset_state(st, prev_state); |
|
if (can_rollback_cpu(st)) |
|
WARN_ON(cpuhp_invoke_callback_range(false, cpu, st, |
|
prev_state)); |
|
} |
|
return ret; |
|
} |
|
|
|
/* |
|
* 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); |
|
st->cpu = cpu; |
|
} |
|
|
|
static int cpuhp_should_run(unsigned int cpu) |
|
{ |
|
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); |
|
|
|
return st->should_run; |
|
} |
|
|
|
/* |
|
* 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; |
|
|
|
if (WARN_ON_ONCE(!st->should_run)) |
|
return; |
|
|
|
/* |
|
* 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(); |
|
|
|
/* |
|
* The BP holds the hotplug lock, but we're now running on the AP, |
|
* ensure that anybody asserting the lock is held, will actually find |
|
* it so. |
|
*/ |
|
lockdep_acquire_cpus_lock(); |
|
cpuhp_lock_acquire(bringup); |
|
|
|
if (st->single) { |
|
state = st->cb_state; |
|
st->should_run = false; |
|
} else { |
|
st->should_run = cpuhp_next_state(bringup, &state, st, st->target); |
|
if (!st->should_run) |
|
goto end; |
|
} |
|
|
|
WARN_ON_ONCE(!cpuhp_is_ap_state(state)); |
|
|
|
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; |
|
} |
|
|
|
end: |
|
cpuhp_lock_release(bringup); |
|
lockdep_release_cpus_lock(); |
|
|
|
if (!st->should_run) |
|
complete_ap_thread(st, bringup); |
|
} |
|
|
|
/* 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; |
|
} |
|
|
|
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; |
|
} |
|
|
|
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)); |
|
} |
|
|
|
/* |
|
* |
|
* Serialize hotplug trainwrecks outside of the cpu_hotplug_lock |
|
* protected region. |
|
* |
|
* The operation is still serialized against concurrent CPU hotplug via |
|
* cpu_add_remove_lock, i.e. CPU map protection. But it is _not_ |
|
* serialized against other hotplug related activity like adding or |
|
* removing of state callbacks and state instances, which invoke either the |
|
* startup or the teardown callback of the affected state. |
|
* |
|
* This is required for subsystems which are unfixable vs. CPU hotplug and |
|
* evade lock inversion problems by scheduling work which has to be |
|
* completed _before_ cpu_up()/_cpu_down() returns. |
|
* |
|
* Don't even think about adding anything to this for any new code or even |
|
* drivers. It's only purpose is to keep existing lock order trainwrecks |
|
* working. |
|
* |
|
* For cpu_down() there might be valid reasons to finish cleanups which are |
|
* not required to be done under cpu_hotplug_lock, but that's a different |
|
* story and would be not invoked via this. |
|
*/ |
|
static void cpu_up_down_serialize_trainwrecks(bool tasks_frozen) |
|
{ |
|
/* |
|
* cpusets delegate hotplug operations to a worker to "solve" the |
|
* lock order problems. Wait for the worker, but only if tasks are |
|
* _not_ frozen (suspend, hibernate) as that would wait forever. |
|
* |
|
* The wait is required because otherwise the hotplug operation |
|
* returns with inconsistent state, which could even be observed in |
|
* user space when a new CPU is brought up. The CPU plug uevent |
|
* would be delivered and user space reacting on it would fail to |
|
* move tasks to the newly plugged CPU up to the point where the |
|
* work has finished because up to that point the newly plugged CPU |
|
* is not assignable in cpusets/cgroups. On unplug that's not |
|
* necessarily a visible issue, but it is still inconsistent state, |
|
* which is the real problem which needs to be "fixed". This can't |
|
* prevent the transient state between scheduling the work and |
|
* returning from waiting for it. |
|
*/ |
|
if (!tasks_frozen) |
|
cpuset_wait_for_hotplug(); |
|
} |
|
|
|
#ifdef CONFIG_HOTPLUG_CPU |
|
#ifndef arch_clear_mm_cpumask_cpu |
|
#define arch_clear_mm_cpumask_cpu(cpu, mm) cpumask_clear_cpu(cpu, mm_cpumask(mm)) |
|
#endif |
|
|
|
/** |
|
* 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; |
|
arch_clear_mm_cpumask_cpu(cpu, t->mm); |
|
task_unlock(t); |
|
} |
|
rcu_read_unlock(); |
|
} |
|
|
|
/* 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; |
|
|
|
/* |
|
* Must be called from CPUHP_TEARDOWN_CPU, which means, as we are going |
|
* down, that the current state is CPUHP_TEARDOWN_CPU - 1. |
|
*/ |
|
WARN_ON(st->state != (CPUHP_TEARDOWN_CPU - 1)); |
|
|
|
/* Invoke the former CPU_DYING callbacks */ |
|
ret = cpuhp_invoke_callback_range(false, cpu, st, target); |
|
|
|
/* |
|
* DYING must not fail! |
|
*/ |
|
WARN_ON_ONCE(ret); |
|
|
|
/* Give up timekeeping duties */ |
|
tick_handover_do_timer(); |
|
/* Remove CPU from timer broadcasting */ |
|
tick_offline_cpu(cpu); |
|
/* 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(st->thread); |
|
|
|
/* |
|
* 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(st->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; |
|
} |
|
|
|
static void cpuhp_complete_idle_dead(void *arg) |
|
{ |
|
struct cpuhp_cpu_state *st = arg; |
|
|
|
complete_ap_thread(st, false); |
|
} |
|
|
|
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); |
|
} |
|
|
|
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; |
|
|
|
ret = cpuhp_invoke_callback_range(false, cpu, st, target); |
|
if (ret) { |
|
pr_debug("CPU DOWN failed (%d) CPU %u state %s (%d)\n", |
|
ret, cpu, cpuhp_get_step(st->state)->name, |
|
st->state); |
|
|
|
cpuhp_reset_state(st, prev_state); |
|
|
|
if (st->state < prev_state) |
|
WARN_ON(cpuhp_invoke_callback_range(true, cpu, st, |
|
prev_state)); |
|
} |
|
|
|
return ret; |
|
} |
|
|
|
/* 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 < prev_state) { |
|
if (st->state == CPUHP_TEARDOWN_CPU) { |
|
cpuhp_reset_state(st, prev_state); |
|
__cpuhp_kick_ap(st); |
|
} else { |
|
WARN(1, "DEAD callback error for CPU%d", cpu); |
|
} |
|
} |
|
|
|
out: |
|
cpus_write_unlock(); |
|
/* |
|
* Do post unplug cleanup. This is still protected against |
|
* concurrent CPU hotplug via cpu_add_remove_lock. |
|
*/ |
|
lockup_detector_cleanup(); |
|
arch_smt_update(); |
|
cpu_up_down_serialize_trainwrecks(tasks_frozen); |
|
return ret; |
|
} |
|
|
|
static int cpu_down_maps_locked(unsigned int cpu, enum cpuhp_state target) |
|
{ |
|
if (cpu_hotplug_disabled) |
|
return -EBUSY; |
|
return _cpu_down(cpu, 0, target); |
|
} |
|
|
|
static int cpu_down(unsigned int cpu, enum cpuhp_state target) |
|
{ |
|
int err; |
|
|
|
cpu_maps_update_begin(); |
|
err = cpu_down_maps_locked(cpu, target); |
|
cpu_maps_update_done(); |
|
return err; |
|
} |
|
|
|
/** |
|
* cpu_device_down - Bring down a cpu device |
|
* @dev: Pointer to the cpu device to offline |
|
* |
|
* This function is meant to be used by device core cpu subsystem only. |
|
* |
|
* Other subsystems should use remove_cpu() instead. |
|
* |
|
* Return: %0 on success or a negative errno code |
|
*/ |
|
int cpu_device_down(struct device *dev) |
|
{ |
|
return cpu_down(dev->id, CPUHP_OFFLINE); |
|
} |
|
|
|
int remove_cpu(unsigned int cpu) |
|
{ |
|
int ret; |
|
|
|
lock_device_hotplug(); |
|
ret = device_offline(get_cpu_device(cpu)); |
|
unlock_device_hotplug(); |
|
|
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(remove_cpu); |
|
|
|
void smp_shutdown_nonboot_cpus(unsigned int primary_cpu) |
|
{ |
|
unsigned int cpu; |
|
int error; |
|
|
|
cpu_maps_update_begin(); |
|
|
|
/* |
|
* Make certain the cpu I'm about to reboot on is online. |
|
* |
|
* This is inline to what migrate_to_reboot_cpu() already do. |
|
*/ |
|
if (!cpu_online(primary_cpu)) |
|
primary_cpu = cpumask_first(cpu_online_mask); |
|
|
|
for_each_online_cpu(cpu) { |
|
if (cpu == primary_cpu) |
|
continue; |
|
|
|
error = cpu_down_maps_locked(cpu, CPUHP_OFFLINE); |
|
if (error) { |
|
pr_err("Failed to offline CPU%d - error=%d", |
|
cpu, error); |
|
break; |
|
} |
|
} |
|
|
|
/* |
|
* Ensure all but the reboot CPU are offline. |
|
*/ |
|
BUG_ON(num_online_cpus() > 1); |
|
|
|
/* |
|
* Make sure the CPUs won't be enabled by someone else after this |
|
* point. Kexec will reboot to a new kernel shortly resetting |
|
* everything along the way. |
|
*/ |
|
cpu_hotplug_disabled++; |
|
|
|
cpu_maps_update_done(); |
|
} |
|
|
|
#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. */ |
|
cpumask_set_cpu(cpu, &cpus_booted_once_mask); |
|
ret = cpuhp_invoke_callback_range(true, cpu, st, target); |
|
|
|
/* |
|
* STARTING must not fail! |
|
*/ |
|
WARN_ON_ONCE(ret); |
|
} |
|
|
|
/* |
|
* Called from the idle task. Wake up the controlling task which brings 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; |
|
|
|
/* |
|
* Unpart the stopper thread before we start the idle loop (and start |
|
* scheduling); this ensures the stopper task is always available. |
|
*/ |
|
stop_machine_unpark(smp_processor_id()); |
|
|
|
st->state = CPUHP_AP_ONLINE_IDLE; |
|
complete_ap_thread(st, true); |
|
} |
|
|
|
/* 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 cpu_up() might have raced with another |
|
* caller. Nothing to do. |
|
*/ |
|
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(); |
|
arch_smt_update(); |
|
cpu_up_down_serialize_trainwrecks(tasks_frozen); |
|
return ret; |
|
} |
|
|
|
static int 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; |
|
} |
|
if (!cpu_smt_allowed(cpu)) { |
|
err = -EPERM; |
|
goto out; |
|
} |
|
|
|
err = _cpu_up(cpu, 0, target); |
|
out: |
|
cpu_maps_update_done(); |
|
return err; |
|
} |
|
|
|
/** |
|
* cpu_device_up - Bring up a cpu device |
|
* @dev: Pointer to the cpu device to online |
|
* |
|
* This function is meant to be used by device core cpu subsystem only. |
|
* |
|
* Other subsystems should use add_cpu() instead. |
|
* |
|
* Return: %0 on success or a negative errno code |
|
*/ |
|
int cpu_device_up(struct device *dev) |
|
{ |
|
return cpu_up(dev->id, CPUHP_ONLINE); |
|
} |
|
|
|
int add_cpu(unsigned int cpu) |
|
{ |
|
int ret; |
|
|
|
lock_device_hotplug(); |
|
ret = device_online(get_cpu_device(cpu)); |
|
unlock_device_hotplug(); |
|
|
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(add_cpu); |
|
|
|
/** |
|
* bringup_hibernate_cpu - Bring up the CPU that we hibernated on |
|
* @sleep_cpu: The cpu we hibernated on and should be brought up. |
|
* |
|
* On some architectures like arm64, we can hibernate on any CPU, but on |
|
* wake up the CPU we hibernated on might be offline as a side effect of |
|
* using maxcpus= for example. |
|
* |
|
* Return: %0 on success or a negative errno code |
|
*/ |
|
int bringup_hibernate_cpu(unsigned int sleep_cpu) |
|
{ |
|
int ret; |
|
|
|
if (!cpu_online(sleep_cpu)) { |
|
pr_info("Hibernated on a CPU that is offline! Bringing CPU up.\n"); |
|
ret = cpu_up(sleep_cpu, CPUHP_ONLINE); |
|
if (ret) { |
|
pr_err("Failed to bring hibernate-CPU up!\n"); |
|
return ret; |
|
} |
|
} |
|
return 0; |
|
} |
|
|
|
void bringup_nonboot_cpus(unsigned int setup_max_cpus) |
|
{ |
|
unsigned int cpu; |
|
|
|
for_each_present_cpu(cpu) { |
|
if (num_online_cpus() >= setup_max_cpus) |
|
break; |
|
if (!cpu_online(cpu)) |
|
cpu_up(cpu, CPUHP_ONLINE); |
|
} |
|
} |
|
|
|
#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 (primary == -1) { |
|
primary = cpumask_first(cpu_online_mask); |
|
if (!housekeeping_cpu(primary, HK_FLAG_TIMER)) |
|
primary = housekeeping_any_cpu(HK_FLAG_TIMER); |
|
} else { |
|
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; |
|
|
|
if (pm_wakeup_pending()) { |
|
pr_info("Wakeup pending. Abort CPU freeze\n"); |
|
error = -EBUSY; |
|
break; |
|
} |
|
|
|
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 freeze_secondary_cpus() users are |
|
* supposed to do thaw_secondary_cpus() on the failure path. |
|
*/ |
|
cpu_hotplug_disabled++; |
|
|
|
cpu_maps_update_done(); |
|
return error; |
|
} |
|
|
|
void __weak arch_thaw_secondary_cpus_begin(void) |
|
{ |
|
} |
|
|
|
void __weak arch_thaw_secondary_cpus_end(void) |
|
{ |
|
} |
|
|
|
void thaw_secondary_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_thaw_secondary_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_thaw_secondary_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 */ |
|
|
|
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:prepare", |
|
.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 = finish_cpu, |
|
.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 control processor until the plugged processor manages |
|
* this itself. |
|
*/ |
|
[CPUHP_TEARDOWN_CPU] = { |
|
.name = "cpu:teardown", |
|
.startup.single = NULL, |
|
.teardown.single = takedown_cpu, |
|
.cant_stop = true, |
|
}, |
|
|
|
[CPUHP_AP_SCHED_WAIT_EMPTY] = { |
|
.name = "sched:waitempty", |
|
.startup.single = NULL, |
|
.teardown.single = sched_cpu_wait_empty, |
|
}, |
|
|
|
/* Handle smpboot threads park/unpark */ |
|
[CPUHP_AP_SMPBOOT_THREADS] = { |
|
.name = "smpboot/threads:online", |
|
.startup.single = smpboot_unpark_threads, |
|
.teardown.single = smpboot_park_threads, |
|
}, |
|
[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_WATCHDOG_ONLINE] = { |
|
.name = "lockup_detector:online", |
|
.startup.single = lockup_detector_online_cpu, |
|
.teardown.single = lockup_detector_offline_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; |
|
} |
|
|
|
/* |
|
* 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; |
|
} |
|
|
|
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; |
|
} |
|
|
|
static void *cpuhp_get_teardown_cb(enum cpuhp_state state) |
|
{ |
|
return cpuhp_get_step(state)->teardown.single; |
|
} |
|
|
|
/* |
|
* 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 (cpuhp_step_empty(bringup, sp)) |
|
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; |
|
} |
|
|
|
/* |
|
* 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); |
|
} |
|
} |
|
|
|
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; |
|
} |
|
|
|
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; |
|
} |
|
EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance); |
|
|
|
/** |
|
* __cpuhp_setup_state_cpuslocked - Setup the callbacks for an hotplug machine state |
|
* @state: The state to setup |
|
* @name: Name of the step |
|
* @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. |
|
* Return: |
|
* 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; |
|
} |
|
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; |
|
} |
|
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; |
|
} |
|
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); |
|
} |
|
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(); |
|
} |
|
EXPORT_SYMBOL(__cpuhp_remove_state); |
|
|
|
#ifdef CONFIG_HOTPLUG_SMT |
|
static void cpuhp_offline_cpu_device(unsigned int cpu) |
|
{ |
|
struct device *dev = get_cpu_device(cpu); |
|
|
|
dev->offline = true; |
|
/* Tell user space about the state change */ |
|
kobject_uevent(&dev->kobj, KOBJ_OFFLINE); |
|
} |
|
|
|
static void cpuhp_online_cpu_device(unsigned int cpu) |
|
{ |
|
struct device *dev = get_cpu_device(cpu); |
|
|
|
dev->offline = false; |
|
/* Tell user space about the state change */ |
|
kobject_uevent(&dev->kobj, KOBJ_ONLINE); |
|
} |
|
|
|
int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval) |
|
{ |
|
int cpu, ret = 0; |
|
|
|
cpu_maps_update_begin(); |
|
for_each_online_cpu(cpu) { |
|
if (topology_is_primary_thread(cpu)) |
|
continue; |
|
ret = cpu_down_maps_locked(cpu, CPUHP_OFFLINE); |
|
if (ret) |
|
break; |
|
/* |
|
* As this needs to hold the cpu maps lock it's impossible |
|
* to call device_offline() because that ends up calling |
|
* cpu_down() which takes cpu maps lock. cpu maps lock |
|
* needs to be held as this might race against in kernel |
|
* abusers of the hotplug machinery (thermal management). |
|
* |
|
* So nothing would update device:offline state. That would |
|
* leave the sysfs entry stale and prevent onlining after |
|
* smt control has been changed to 'off' again. This is |
|
* called under the sysfs hotplug lock, so it is properly |
|
* serialized against the regular offline usage. |
|
*/ |
|
cpuhp_offline_cpu_device(cpu); |
|
} |
|
if (!ret) |
|
cpu_smt_control = ctrlval; |
|
cpu_maps_update_done(); |
|
return ret; |
|
} |
|
|
|
int cpuhp_smt_enable(void) |
|
{ |
|
int cpu, ret = 0; |
|
|
|
cpu_maps_update_begin(); |
|
cpu_smt_control = CPU_SMT_ENABLED; |
|
for_each_present_cpu(cpu) { |
|
/* Skip online CPUs and CPUs on offline nodes */ |
|
if (cpu_online(cpu) || !node_online(cpu_to_node(cpu))) |
|
continue; |
|
ret = _cpu_up(cpu, 0, CPUHP_ONLINE); |
|
if (ret) |
|
break; |
|
/* See comment in cpuhp_smt_disable() */ |
|
cpuhp_online_cpu_device(cpu); |
|
} |
|
cpu_maps_update_done(); |
|
return ret; |
|
} |
|
#endif |
|
|
|
#if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU) |
|
static ssize_t state_show(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_RO(state); |
|
|
|
static ssize_t target_store(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 = cpu_up(dev->id, target); |
|
else |
|
ret = cpu_down(dev->id, target); |
|
out: |
|
unlock_device_hotplug(); |
|
return ret ? ret : count; |
|
} |
|
|
|
static ssize_t target_show(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_RW(target); |
|
|
|
static ssize_t fail_store(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; |
|
|
|
if (fail == CPUHP_INVALID) { |
|
st->fail = fail; |
|
return count; |
|
} |
|
|
|
if (fail < CPUHP_OFFLINE || fail > CPUHP_ONLINE) |
|
return -EINVAL; |
|
|
|
/* |
|
* Cannot fail STARTING/DYING callbacks. |
|
*/ |
|
if (cpuhp_is_atomic_state(fail)) |
|
return -EINVAL; |
|
|
|
/* |
|
* DEAD callbacks cannot fail... |
|
* ... neither can CPUHP_BRINGUP_CPU during hotunplug. The latter |
|
* triggering STARTING callbacks, a failure in this state would |
|
* hinder rollback. |
|
*/ |
|
if (fail <= CPUHP_BRINGUP_CPU && st->state > CPUHP_BRINGUP_CPU) |
|
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; |
|
} |
|
|
|
static ssize_t fail_show(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); |
|
} |
|
|
|
static DEVICE_ATTR_RW(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 states_show(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_RO(states); |
|
|
|
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 |
|
}; |
|
|
|
#ifdef CONFIG_HOTPLUG_SMT |
|
|
|
static ssize_t |
|
__store_smt_control(struct device *dev, struct device_attribute *attr, |
|
const char *buf, size_t count) |
|
{ |
|
int ctrlval, ret; |
|
|
|
if (sysfs_streq(buf, "on")) |
|
ctrlval = CPU_SMT_ENABLED; |
|
else if (sysfs_streq(buf, "off")) |
|
ctrlval = CPU_SMT_DISABLED; |
|
else if (sysfs_streq(buf, "forceoff")) |
|
ctrlval = CPU_SMT_FORCE_DISABLED; |
|
else |
|
return -EINVAL; |
|
|
|
if (cpu_smt_control == CPU_SMT_FORCE_DISABLED) |
|
return -EPERM; |
|
|
|
if (cpu_smt_control == CPU_SMT_NOT_SUPPORTED) |
|
return -ENODEV; |
|
|
|
ret = lock_device_hotplug_sysfs(); |
|
if (ret) |
|
return ret; |
|
|
|
if (ctrlval != cpu_smt_control) { |
|
switch (ctrlval) { |
|
case CPU_SMT_ENABLED: |
|
ret = cpuhp_smt_enable(); |
|
break; |
|
case CPU_SMT_DISABLED: |
|
case CPU_SMT_FORCE_DISABLED: |
|
ret = cpuhp_smt_disable(ctrlval); |
|
break; |
|
} |
|
} |
|
|
|
unlock_device_hotplug(); |
|
return ret ? ret : count; |
|
} |
|
|
|
#else /* !CONFIG_HOTPLUG_SMT */ |
|
static ssize_t |
|
__store_smt_control(struct device *dev, struct device_attribute *attr, |
|
const char *buf, size_t count) |
|
{ |
|
return -ENODEV; |
|
} |
|
#endif /* CONFIG_HOTPLUG_SMT */ |
|
|
|
static const char *smt_states[] = { |
|
[CPU_SMT_ENABLED] = "on", |
|
[CPU_SMT_DISABLED] = "off", |
|
[CPU_SMT_FORCE_DISABLED] = "forceoff", |
|
[CPU_SMT_NOT_SUPPORTED] = "notsupported", |
|
[CPU_SMT_NOT_IMPLEMENTED] = "notimplemented", |
|
}; |
|
|
|
static ssize_t control_show(struct device *dev, |
|
struct device_attribute *attr, char *buf) |
|
{ |
|
const char *state = smt_states[cpu_smt_control]; |
|
|
|
return snprintf(buf, PAGE_SIZE - 2, "%s\n", state); |
|
} |
|
|
|
static ssize_t control_store(struct device *dev, struct device_attribute *attr, |
|
const char *buf, size_t count) |
|
{ |
|
return __store_smt_control(dev, attr, buf, count); |
|
} |
|
static DEVICE_ATTR_RW(control); |
|
|
|
static ssize_t active_show(struct device *dev, |
|
struct device_attribute *attr, char *buf) |
|
{ |
|
return snprintf(buf, PAGE_SIZE - 2, "%d\n", sched_smt_active()); |
|
} |
|
static DEVICE_ATTR_RO(active); |
|
|
|
static struct attribute *cpuhp_smt_attrs[] = { |
|
&dev_attr_control.attr, |
|
&dev_attr_active.attr, |
|
NULL |
|
}; |
|
|
|
static const struct attribute_group cpuhp_smt_attr_group = { |
|
.attrs = cpuhp_smt_attrs, |
|
.name = "smt", |
|
NULL |
|
}; |
|
|
|
static int __init cpu_smt_sysfs_init(void) |
|
{ |
|
return sysfs_create_group(&cpu_subsys.dev_root->kobj, |
|
&cpuhp_smt_attr_group); |
|
} |
|
|
|
static int __init cpuhp_sysfs_init(void) |
|
{ |
|
int cpu, ret; |
|
|
|
ret = cpu_smt_sysfs_init(); |
|
if (ret) |
|
return 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 /* CONFIG_SYSFS && CONFIG_HOTPLUG_CPU */ |
|
|
|
/* |
|
* 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); |
|
|
|
struct cpumask __cpu_dying_mask __read_mostly; |
|
EXPORT_SYMBOL(__cpu_dying_mask); |
|
|
|
atomic_t __num_online_cpus __read_mostly; |
|
EXPORT_SYMBOL(__num_online_cpus); |
|
|
|
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); |
|
} |
|
|
|
void set_cpu_online(unsigned int cpu, bool online) |
|
{ |
|
/* |
|
* atomic_inc/dec() is required to handle the horrid abuse of this |
|
* function by the reboot and kexec code which invoke it from |
|
* IPI/NMI broadcasts when shutting down CPUs. Invocation from |
|
* regular CPU hotplug is properly serialized. |
|
* |
|
* Note, that the fact that __num_online_cpus is of type atomic_t |
|
* does not protect readers which are not serialized against |
|
* concurrent hotplug operations. |
|
*/ |
|
if (online) { |
|
if (!cpumask_test_and_set_cpu(cpu, &__cpu_online_mask)) |
|
atomic_inc(&__num_online_cpus); |
|
} else { |
|
if (cpumask_test_and_clear_cpu(cpu, &__cpu_online_mask)) |
|
atomic_dec(&__num_online_cpus); |
|
} |
|
} |
|
|
|
/* |
|
* 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 |
|
} |
|
|
|
/* |
|
* Must be called _AFTER_ setting up the per_cpu areas |
|
*/ |
|
void __init boot_cpu_hotplug_init(void) |
|
{ |
|
#ifdef CONFIG_SMP |
|
cpumask_set_cpu(smp_processor_id(), &cpus_booted_once_mask); |
|
#endif |
|
this_cpu_write(cpuhp_state.state, CPUHP_ONLINE); |
|
} |
|
|
|
/* |
|
* These are used for a global "mitigations=" cmdline option for toggling |
|
* optional CPU mitigations. |
|
*/ |
|
enum cpu_mitigations { |
|
CPU_MITIGATIONS_OFF, |
|
CPU_MITIGATIONS_AUTO, |
|
CPU_MITIGATIONS_AUTO_NOSMT, |
|
}; |
|
|
|
static enum cpu_mitigations cpu_mitigations __ro_after_init = |
|
CPU_MITIGATIONS_AUTO; |
|
|
|
static int __init mitigations_parse_cmdline(char *arg) |
|
{ |
|
if (!strcmp(arg, "off")) |
|
cpu_mitigations = CPU_MITIGATIONS_OFF; |
|
else if (!strcmp(arg, "auto")) |
|
cpu_mitigations = CPU_MITIGATIONS_AUTO; |
|
else if (!strcmp(arg, "auto,nosmt")) |
|
cpu_mitigations = CPU_MITIGATIONS_AUTO_NOSMT; |
|
else |
|
pr_crit("Unsupported mitigations=%s, system may still be vulnerable\n", |
|
arg); |
|
|
|
return 0; |
|
} |
|
early_param("mitigations", mitigations_parse_cmdline); |
|
|
|
/* mitigations=off */ |
|
bool cpu_mitigations_off(void) |
|
{ |
|
return cpu_mitigations == CPU_MITIGATIONS_OFF; |
|
} |
|
EXPORT_SYMBOL_GPL(cpu_mitigations_off); |
|
|
|
/* mitigations=auto,nosmt */ |
|
bool cpu_mitigations_auto_nosmt(void) |
|
{ |
|
return cpu_mitigations == CPU_MITIGATIONS_AUTO_NOSMT; |
|
} |
|
EXPORT_SYMBOL_GPL(cpu_mitigations_auto_nosmt);
|
|
|