diff options
Diffstat (limited to 'kernel/cpu.c')
| -rw-r--r-- | kernel/cpu.c | 615 |
1 files changed, 463 insertions, 152 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 9c706af713fb..bbad5e375d3b 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -3,6 +3,7 @@ * * This code is licenced under the GPL. */ +#include <linux/sched/mm.h> #include <linux/proc_fs.h> #include <linux/smp.h> #include <linux/init.h> @@ -30,7 +31,11 @@ #include <linux/smpboot.h> #include <linux/relay.h> #include <linux/slab.h> +#include <linux/scs.h> #include <linux/percpu-rwsem.h> +#include <linux/cpuset.h> +#include <linux/random.h> +#include <linux/cc_platform.h> #include <trace/events/power.h> #define CREATE_TRACE_POINTS @@ -39,14 +44,19 @@ #include "smpboot.h" /** - * cpuhp_cpu_state - Per cpu hotplug state storage + * struct cpuhp_cpu_state - Per cpu hotplug state storage * @state: The current cpu state * @target: The target state + * @fail: Current CPU hotplug callback state * @thread: Pointer to the hotplug thread * @should_run: Thread should execute * @rollback: Perform a rollback * @single: Single callback invocation * @bringup: Single callback bringup or teardown selector + * @cpu: CPU number + * @node: Remote CPU node; for multi-instance, do a + * single entry callback for install/remove + * @last: For multi-instance rollback, remember how far we got * @cb_state: The state for a single callback (install/uninstall) * @result: Result of the operation * @done_up: Signal completion to the issuer of the task for cpu-up @@ -103,11 +113,12 @@ static inline void cpuhp_lock_release(bool bringup) { } #endif /** - * cpuhp_step - Hotplug state machine step + * struct cpuhp_step - Hotplug state machine step * @name: Name of the step * @startup: Startup function of the step * @teardown: Teardown function of the step * @cant_stop: Bringup/teardown can't be stopped at this step + * @multi_instance: State has multiple instances which get added afterwards */ struct cpuhp_step { const char *name; @@ -121,7 +132,9 @@ struct cpuhp_step { int (*multi)(unsigned int cpu, struct hlist_node *node); } teardown; + /* private: */ struct hlist_head list; + /* public: */ bool cant_stop; bool multi_instance; }; @@ -134,8 +147,13 @@ static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state) return cpuhp_hp_states + state; } +static bool cpuhp_step_empty(bool bringup, struct cpuhp_step *step) +{ + return bringup ? !step->startup.single : !step->teardown.single; +} + /** - * cpuhp_invoke_callback _ Invoke the callbacks for a given state + * cpuhp_invoke_callback - Invoke the callbacks for a given state * @cpu: The cpu for which the callback should be invoked * @state: The state to do callbacks for * @bringup: True if the bringup callback should be invoked @@ -143,6 +161,8 @@ static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state) * @lastp: For multi-instance rollback, remember how far we got * * Called from cpu hotplug and from the state register machinery. + * + * Return: %0 on success or a negative errno code */ static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state, bool bringup, struct hlist_node *node, @@ -156,26 +176,24 @@ static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state, if (st->fail == state) { st->fail = CPUHP_INVALID; - - if (!(bringup ? step->startup.single : step->teardown.single)) - return 0; - return -EAGAIN; } + if (cpuhp_step_empty(bringup, step)) { + WARN_ON_ONCE(1); + return 0; + } + if (!step->multi_instance) { WARN_ON_ONCE(lastp && *lastp); cb = bringup ? step->startup.single : step->teardown.single; - if (!cb) - return 0; + trace_cpuhp_enter(cpu, st->target, state, cb); ret = cb(cpu); trace_cpuhp_exit(cpu, st->state, state, ret); return ret; } cbm = bringup ? step->startup.multi : step->teardown.multi; - if (!cbm) - return 0; /* Single invocation for instance add/remove */ if (node) { @@ -329,14 +347,21 @@ void lockdep_assert_cpus_held(void) percpu_rwsem_assert_held(&cpu_hotplug_lock); } +#ifdef CONFIG_LOCKDEP +int lockdep_is_cpus_held(void) +{ + return percpu_rwsem_is_held(&cpu_hotplug_lock); +} +#endif + static void lockdep_acquire_cpus_lock(void) { - rwsem_acquire(&cpu_hotplug_lock.rw_sem.dep_map, 0, 0, _THIS_IP_); + rwsem_acquire(&cpu_hotplug_lock.dep_map, 0, 0, _THIS_IP_); } static void lockdep_release_cpus_lock(void) { - rwsem_release(&cpu_hotplug_lock.rw_sem.dep_map, _THIS_IP_); + rwsem_release(&cpu_hotplug_lock.dep_map, _THIS_IP_); } /* @@ -432,7 +457,7 @@ static inline bool cpu_smt_allowed(unsigned int cpu) /* * On x86 it's required to boot all logical CPUs at least once so * that the init code can get a chance to set CR4.MCE on each - * CPU. Otherwise, a broadacasted MCE observing CR4.MCE=0b on any + * CPU. Otherwise, a broadcasted MCE observing CR4.MCE=0b on any * core will shutdown the machine. */ return !cpumask_test_cpu(cpu, &cpus_booted_once_mask); @@ -450,23 +475,38 @@ static inline bool cpu_smt_allowed(unsigned int cpu) { return true; } #endif static inline enum cpuhp_state -cpuhp_set_state(struct cpuhp_cpu_state *st, enum cpuhp_state target) +cpuhp_set_state(int cpu, struct cpuhp_cpu_state *st, enum cpuhp_state target) { enum cpuhp_state prev_state = st->state; + bool bringup = st->state < target; st->rollback = false; st->last = NULL; st->target = target; st->single = false; - st->bringup = st->state < target; + st->bringup = bringup; + if (cpu_dying(cpu) != !bringup) + set_cpu_dying(cpu, !bringup); return prev_state; } static inline void -cpuhp_reset_state(struct cpuhp_cpu_state *st, enum cpuhp_state prev_state) +cpuhp_reset_state(int cpu, struct cpuhp_cpu_state *st, + enum cpuhp_state prev_state) { + bool bringup = !st->bringup; + + st->target = prev_state; + + /* + * Already rolling back. No need invert the bringup value or to change + * the current state. + */ + if (st->rollback) + return; + st->rollback = true; /* @@ -480,8 +520,9 @@ cpuhp_reset_state(struct cpuhp_cpu_state *st, enum cpuhp_state prev_state) st->state++; } - st->target = prev_state; - st->bringup = !st->bringup; + st->bringup = bringup; + if (cpu_dying(cpu) != !bringup) + set_cpu_dying(cpu, !bringup); } /* Regular hotplug invocation of the AP hotplug thread */ @@ -501,15 +542,16 @@ static void __cpuhp_kick_ap(struct cpuhp_cpu_state *st) wait_for_ap_thread(st, st->bringup); } -static int cpuhp_kick_ap(struct cpuhp_cpu_state *st, enum cpuhp_state target) +static int cpuhp_kick_ap(int cpu, struct cpuhp_cpu_state *st, + enum cpuhp_state target) { enum cpuhp_state prev_state; int ret; - prev_state = cpuhp_set_state(st, target); + prev_state = cpuhp_set_state(cpu, st, target); __cpuhp_kick_ap(st); if ((ret = st->result)) { - cpuhp_reset_state(st, prev_state); + cpuhp_reset_state(cpu, st, prev_state); __cpuhp_kick_ap(st); } @@ -541,7 +583,7 @@ static int bringup_wait_for_ap(unsigned int cpu) if (st->target <= CPUHP_AP_ONLINE_IDLE) return 0; - return cpuhp_kick_ap(st, st->target); + return cpuhp_kick_ap(cpu, st, st->target); } static int bringup_cpu(unsigned int cpu) @@ -550,6 +592,12 @@ static int bringup_cpu(unsigned int cpu) int ret; /* + * Reset stale stack state from the last time this CPU was online. + */ + scs_task_reset(idle); + kasan_unpoison_task_stack(idle); + + /* * 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. @@ -564,14 +612,72 @@ static int bringup_cpu(unsigned int cpu) 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 */ -static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st) +/* + * 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) { - for (st->state--; st->state > st->target; st->state--) - cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL); + 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) @@ -594,16 +700,16 @@ static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, enum cpuhp_state prev_state = st->state; int ret = 0; - while (st->state < target) { - st->state++; - ret = cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL); - if (ret) { - if (can_rollback_cpu(st)) { - st->target = prev_state; - undo_cpu_up(cpu, st); - } - break; - } + 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(cpu, st, prev_state); + if (can_rollback_cpu(st)) + WARN_ON(cpuhp_invoke_callback_range(false, cpu, st, + prev_state)); } return ret; } @@ -611,14 +717,6 @@ static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, /* * 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); -} - static int cpuhp_should_run(unsigned int cpu) { struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); @@ -667,17 +765,9 @@ static void cpuhp_thread_fun(unsigned int cpu) state = st->cb_state; st->should_run = false; } else { - if (bringup) { - st->state++; - state = st->state; - st->should_run = (st->state < st->target); - WARN_ON_ONCE(st->state > st->target); - } else { - state = st->state; - st->state--; - st->should_run = (st->state > st->target); - WARN_ON_ONCE(st->state < st->target); - } + 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)); @@ -705,6 +795,7 @@ static void cpuhp_thread_fun(unsigned int cpu) st->should_run = false; } +end: cpuhp_lock_release(bringup); lockdep_release_cpus_lock(); @@ -777,7 +868,7 @@ static int cpuhp_kick_ap_work(unsigned int cpu) cpuhp_lock_release(true); trace_cpuhp_enter(cpu, st->target, prev_state, cpuhp_kick_ap_work); - ret = cpuhp_kick_ap(st, st->target); + ret = cpuhp_kick_ap(cpu, st, st->target); trace_cpuhp_exit(cpu, st->state, prev_state, ret); return ret; @@ -785,20 +876,82 @@ static int cpuhp_kick_ap_work(unsigned int cpu) 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, }; +static __init void cpuhp_init_state(void) +{ + struct cpuhp_cpu_state *st; + int cpu; + + for_each_possible_cpu(cpu) { + st = per_cpu_ptr(&cpuhp_state, cpu); + init_completion(&st->done_up); + init_completion(&st->done_down); + } +} + void __init cpuhp_threads_init(void) { + cpuhp_init_state(); 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 @@ -834,7 +987,7 @@ void clear_tasks_mm_cpumask(int cpu) t = find_lock_task_mm(p); if (!t) continue; - cpumask_clear_cpu(cpu, mm_cpumask(t->mm)); + arch_clear_mm_cpumask_cpu(cpu, t->mm); task_unlock(t); } rcu_read_unlock(); @@ -854,19 +1007,18 @@ static int take_cpu_down(void *_param) return err; /* - * We get here while we are in CPUHP_TEARDOWN_CPU state and we must not - * do this step again. + * 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); - st->state--; + WARN_ON(st->state != (CPUHP_TEARDOWN_CPU - 1)); + /* Invoke the former CPU_DYING callbacks */ - for (; st->state > target; st->state--) { - ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL); - /* - * DYING must not fail! - */ - WARN_ON_ONCE(ret); - } + 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(); @@ -883,7 +1035,7 @@ static int takedown_cpu(unsigned int cpu) int err; /* Park the smpboot threads */ - kthread_park(per_cpu_ptr(&cpuhp_state, cpu)->thread); + kthread_park(st->thread); /* * Prevent irq alloc/free while the dying cpu reorganizes the @@ -899,7 +1051,7 @@ static int takedown_cpu(unsigned int cpu) /* CPU refused to die */ irq_unlock_sparse(); /* Unpark the hotplug thread so we can rollback there */ - kthread_unpark(per_cpu_ptr(&cpuhp_state, cpu)->thread); + kthread_unpark(st->thread); return err; } BUG_ON(cpu_online(cpu)); @@ -948,27 +1100,25 @@ void cpuhp_report_idle_dead(void) cpuhp_complete_idle_dead, st, 0); } -static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st) -{ - for (st->state++; st->state < st->target; st->state++) - cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL); -} - static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, enum cpuhp_state target) { enum cpuhp_state prev_state = st->state; int ret = 0; - for (; st->state > target; st->state--) { - ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL); - if (ret) { - st->target = prev_state; - if (st->state < prev_state) - undo_cpu_down(cpu, st); - break; - } + 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(cpu, st, prev_state); + + if (st->state < prev_state) + WARN_ON(cpuhp_invoke_callback_range(true, cpu, st, + prev_state)); } + return ret; } @@ -989,7 +1139,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, cpuhp_tasks_frozen = tasks_frozen; - prev_state = cpuhp_set_state(st, target); + prev_state = cpuhp_set_state(cpu, st, target); /* * If the current CPU state is in the range of the AP hotplug thread, * then we need to kick the thread. @@ -1018,9 +1168,13 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, * to do the further cleanups. */ ret = cpuhp_down_callbacks(cpu, st, target); - if (ret && st->state == CPUHP_TEARDOWN_CPU && st->state < prev_state) { - cpuhp_reset_state(st, prev_state); - __cpuhp_kick_ap(st); + if (ret && st->state < prev_state) { + if (st->state == CPUHP_TEARDOWN_CPU) { + cpuhp_reset_state(cpu, st, prev_state); + __cpuhp_kick_ap(st); + } else { + WARN(1, "DEAD callback error for CPU%d", cpu); + } } out: @@ -1031,17 +1185,24 @@ out: */ 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 the platform does not support hotplug, report it explicitly to + * differentiate it from a transient offlining failure. + */ + if (cc_platform_has(CC_ATTR_HOTPLUG_DISABLED)) + return -EOPNOTSUPP; if (cpu_hotplug_disabled) return -EBUSY; return _cpu_down(cpu, 0, target); } -static int do_cpu_down(unsigned int cpu, enum cpuhp_state target) +static int cpu_down(unsigned int cpu, enum cpuhp_state target) { int err; @@ -1051,11 +1212,74 @@ static int do_cpu_down(unsigned int cpu, enum cpuhp_state target) return err; } -int cpu_down(unsigned int cpu) +/** + * 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 do_cpu_down(cpu, CPUHP_OFFLINE); + 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(); } -EXPORT_SYMBOL(cpu_down); #else #define takedown_cpu NULL @@ -1076,14 +1300,12 @@ void notify_cpu_starting(unsigned int cpu) rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */ cpumask_set_cpu(cpu, &cpus_booted_once_mask); - while (st->state < target) { - st->state++; - ret = cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL); - /* - * STARTING must not fail! - */ - WARN_ON_ONCE(ret); - } + ret = cpuhp_invoke_callback_range(true, cpu, st, target); + + /* + * STARTING must not fail! + */ + WARN_ON_ONCE(ret); } /* @@ -1124,8 +1346,8 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target) } /* - * The caller of do_cpu_up might have raced with another - * caller. Ignore it for now. + * The caller of cpu_up() might have raced with another + * caller. Nothing to do. */ if (st->state >= target) goto out; @@ -1141,7 +1363,7 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target) cpuhp_tasks_frozen = tasks_frozen; - cpuhp_set_state(st, target); + cpuhp_set_state(cpu, 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. @@ -1166,10 +1388,11 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target) out: cpus_write_unlock(); arch_smt_update(); + cpu_up_down_serialize_trainwrecks(tasks_frozen); return ret; } -static int do_cpu_up(unsigned int cpu, enum cpuhp_state target) +static int cpu_up(unsigned int cpu, enum cpuhp_state target) { int err = 0; @@ -1203,11 +1426,69 @@ out: return err; } -int cpu_up(unsigned int cpu) +/** + * 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) { - return do_cpu_up(cpu, CPUHP_ONLINE); + 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); + } } -EXPORT_SYMBOL_GPL(cpu_up); #ifdef CONFIG_PM_SLEEP_SMP static cpumask_var_t frozen_cpus; @@ -1219,8 +1500,8 @@ int freeze_secondary_cpus(int primary) 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); + if (!housekeeping_cpu(primary, HK_TYPE_TIMER)) + primary = housekeeping_any_cpu(HK_TYPE_TIMER); } else { if (!cpu_online(primary)) primary = cpumask_first(cpu_online_mask); @@ -1261,8 +1542,8 @@ int freeze_secondary_cpus(int primary) /* * Make sure the CPUs won't be enabled by someone else. We need to do - * this even in case of failure as all disable_nonboot_cpus() users are - * supposed to do enable_nonboot_cpus() on the failure path. + * 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++; @@ -1270,15 +1551,15 @@ int freeze_secondary_cpus(int primary) return error; } -void __weak arch_enable_nonboot_cpus_begin(void) +void __weak arch_thaw_secondary_cpus_begin(void) { } -void __weak arch_enable_nonboot_cpus_end(void) +void __weak arch_thaw_secondary_cpus_end(void) { } -void enable_nonboot_cpus(void) +void thaw_secondary_cpus(void) { int cpu, error; @@ -1290,7 +1571,7 @@ void enable_nonboot_cpus(void) pr_info("Enabling non-boot CPUs ...\n"); - arch_enable_nonboot_cpus_begin(); + arch_thaw_secondary_cpus_begin(); for_each_cpu(cpu, frozen_cpus) { trace_suspend_resume(TPS("CPU_ON"), cpu, true); @@ -1303,7 +1584,7 @@ void enable_nonboot_cpus(void) pr_warn("Error taking CPU%d up: %d\n", cpu, error); } - arch_enable_nonboot_cpus_end(); + arch_thaw_secondary_cpus_end(); cpumask_clear(frozen_cpus); out: @@ -1390,6 +1671,11 @@ static struct cpuhp_step cpuhp_hp_states[] = { .startup.single = perf_event_init_cpu, .teardown.single = perf_event_exit_cpu, }, + [CPUHP_RANDOM_PREPARE] = { + .name = "random:prepare", + .startup.single = random_prepare_cpu, + .teardown.single = NULL, + }, [CPUHP_WORKQUEUE_PREP] = { .name = "workqueue:prepare", .startup.single = workqueue_prepare_cpu, @@ -1434,7 +1720,7 @@ static struct cpuhp_step cpuhp_hp_states[] = { [CPUHP_BRINGUP_CPU] = { .name = "cpu:bringup", .startup.single = bringup_cpu, - .teardown.single = NULL, + .teardown.single = finish_cpu, .cant_stop = true, }, /* Final state before CPU kills itself */ @@ -1471,7 +1757,7 @@ static struct cpuhp_step cpuhp_hp_states[] = { .name = "ap:online", }, /* - * Handled on controll processor until the plugged processor manages + * Handled on control processor until the plugged processor manages * this itself. */ [CPUHP_TEARDOWN_CPU] = { @@ -1480,6 +1766,13 @@ static struct cpuhp_step cpuhp_hp_states[] = { .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", @@ -1506,6 +1799,11 @@ static struct cpuhp_step cpuhp_hp_states[] = { .startup.single = workqueue_online_cpu, .teardown.single = workqueue_offline_cpu, }, + [CPUHP_AP_RANDOM_ONLINE] = { + .name = "random:online", + .startup.single = random_online_cpu, + .teardown.single = NULL, + }, [CPUHP_AP_RCUTREE_ONLINE] = { .name = "RCU/tree:online", .startup.single = rcutree_online_cpu, @@ -1628,8 +1926,7 @@ static int cpuhp_issue_call(int cpu, enum cpuhp_state state, bool bringup, * If there's nothing to do, we done. * Relies on the union for multi_instance. */ - if ((bringup && !sp->startup.single) || - (!bringup && !sp->teardown.single)) + if (cpuhp_step_empty(bringup, sp)) return 0; /* * The non AP bound callbacks can fail on bringup. On teardown @@ -1731,6 +2028,7 @@ 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 @@ -1739,9 +2037,9 @@ EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance); * added afterwards. * * The caller needs to hold cpus read locked while calling this function. - * Returns: + * Return: * On success: - * Positive state number if @state is CPUHP_AP_ONLINE_DYN + * Positive state number if @state is CPUHP_AP_ONLINE_DYN; * 0 for all other states * On failure: proper (negative) error code */ @@ -1987,18 +2285,17 @@ int cpuhp_smt_enable(void) #endif #if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU) -static ssize_t show_cpuhp_state(struct device *dev, - struct device_attribute *attr, char *buf) +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(state, 0444, show_cpuhp_state, NULL); +static DEVICE_ATTR_RO(state); -static ssize_t write_cpuhp_target(struct device *dev, - struct device_attribute *attr, - const char *buf, size_t count) +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; @@ -2028,27 +2325,25 @@ static ssize_t write_cpuhp_target(struct device *dev, goto out; if (st->state < target) - ret = do_cpu_up(dev->id, target); + ret = cpu_up(dev->id, target); else - ret = do_cpu_down(dev->id, target); + ret = cpu_down(dev->id, target); out: unlock_device_hotplug(); return ret ? ret : count; } -static ssize_t show_cpuhp_target(struct device *dev, - struct device_attribute *attr, char *buf) +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(target, 0644, show_cpuhp_target, write_cpuhp_target); +static DEVICE_ATTR_RW(target); - -static ssize_t write_cpuhp_fail(struct device *dev, - struct device_attribute *attr, - const char *buf, size_t count) +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; @@ -2058,6 +2353,11 @@ static ssize_t write_cpuhp_fail(struct device *dev, if (ret) return ret; + if (fail == CPUHP_INVALID) { + st->fail = fail; + return count; + } + if (fail < CPUHP_OFFLINE || fail > CPUHP_ONLINE) return -EINVAL; @@ -2068,6 +2368,15 @@ static ssize_t write_cpuhp_fail(struct device *dev, 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); @@ -2083,15 +2392,15 @@ static ssize_t write_cpuhp_fail(struct device *dev, return count; } -static ssize_t show_cpuhp_fail(struct device *dev, - struct device_attribute *attr, char *buf) +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(fail, 0644, show_cpuhp_fail, write_cpuhp_fail); +static DEVICE_ATTR_RW(fail); static struct attribute *cpuhp_cpu_attrs[] = { &dev_attr_state.attr, @@ -2106,7 +2415,7 @@ static const struct attribute_group cpuhp_cpu_attr_group = { NULL }; -static ssize_t show_cpuhp_states(struct device *dev, +static ssize_t states_show(struct device *dev, struct device_attribute *attr, char *buf) { ssize_t cur, res = 0; @@ -2125,7 +2434,7 @@ static ssize_t show_cpuhp_states(struct device *dev, mutex_unlock(&cpuhp_state_mutex); return res; } -static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL); +static DEVICE_ATTR_RO(states); static struct attribute *cpuhp_cpu_root_attrs[] = { &dev_attr_states.attr, @@ -2198,28 +2507,27 @@ static const char *smt_states[] = { [CPU_SMT_NOT_IMPLEMENTED] = "notimplemented", }; -static ssize_t -show_smt_control(struct device *dev, struct device_attribute *attr, char *buf) +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 -store_smt_control(struct device *dev, struct device_attribute *attr, - const char *buf, size_t count) +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(control, 0644, show_smt_control, store_smt_control); +static DEVICE_ATTR_RW(control); -static ssize_t -show_smt_active(struct device *dev, struct device_attribute *attr, char *buf) +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(active, 0444, show_smt_active, NULL); +static DEVICE_ATTR_RO(active); static struct attribute *cpuhp_smt_attrs[] = { &dev_attr_control.attr, @@ -2311,6 +2619,9 @@ 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); |