12 #include <linux/sched/hotplug.h>
44  * struct cpuhp_cpu_state - Per cpu hotplug state storage
47  * @fail:	Current CPU hotplug callback state
48  * @thread:	Pointer to the hotplug thread
114  * struct cpuhp_step - Hotplug state machine step
161  * Called from cpu hotplug and from the state register machinery.
337 	 * We can't have hotplug operations before userspace starts running,  in lockdep_assert_cpus_held()
338 	 * and some init codepaths will knowingly not take the hotplug lock.  in lockdep_assert_cpus_held()
366  * Wait for currently running CPU hotplug operations to complete (if any) and
367  * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
369  * hotplug path before performing hotplug operations. So acquiring that lock
370  * guarantees mutual exclusion from any currently running hotplug operations.
382 	if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n"))  in __cpu_hotplug_enable()
408  * Architectures that need SMT-specific errata handling during SMT hotplug
525 /* Regular hotplug invocation of the AP hotplug thread */
566 	/* Unpark the hotplug thread of the target cpu */  in bringup_wait_for_ap()
621  * Hotplug state machine related functions
678 	 * When CPU hotplug is disabled, then taking the CPU down is not  in can_rollback_cpu()
708  * The cpu hotplug threads manage the bringup and teardown of the cpus
756 	 * The BP holds the hotplug lock, but we're now running on the AP,  in cpuhp_thread_fun()
823 	 * If we are up and running, use the hotplug thread. For early calls  in cpuhp_invoke_ap_callback()
850 	 * Clean up the leftovers so the next hotplug operation wont use stale  in cpuhp_invoke_ap_callback()
893  * Serialize hotplug trainwrecks outside of the cpu_hotplug_lock
896  * The operation is still serialized against concurrent CPU hotplug via
898  * serialized against other hotplug related activity like adding or
902  * This is required for subsystems which are unfixable vs. CPU hotplug and
917 	 * cpusets delegate hotplug operations to a worker to "solve" the  in cpu_up_down_serialize_trainwrecks()
921 	 * The wait is required because otherwise the hotplug operation  in cpu_up_down_serialize_trainwrecks()
1040 		/* Unpark the hotplug thread so we can rollback there */  in takedown_cpu()
1131 	 * If the current CPU state is in the range of the AP hotplug thread,  in _cpu_down()
1145 		 * We might have stopped still in the range of the AP hotplug  in _cpu_down()
1171 	 * concurrent CPU hotplug via cpu_add_remove_lock.  in _cpu_down()
1294  * hotplug thread of the upcoming CPU up and then delegates the rest of the
1295  * online bringup to the hotplug thread.
1349 	 * If the current CPU state is in the range of the AP hotplug thread,  in _cpu_up()
1364 	 * CPUHP_BRINGUP_CPU. After that the AP hotplug thread is  in _cpu_up()
1493 	 * with the userspace trying to use the CPU hotplug at the same time  in freeze_secondary_cpus()
1547 	/* Allow everyone to use the CPU hotplug again */  in thaw_secondary_cpus()
1584  * When callbacks for CPU hotplug notifications are being executed, we must
1588  * Hence we need to prevent the freezer from racing with regular CPU hotplug.
1591  * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
1623 	 * to disable cpu hotplug to avoid cpu hotplug race.  in cpu_hotplug_pm_sync_init()
1840 	WARN(1, "No more dynamic states available for CPU hotplug\n");  in cpuhp_reserve_state()
1849 	/* (Un)Install the callbacks for further cpu hotplug operations */  in cpuhp_store_callbacks()
1860 	 * dangling, which causes wreckage on the next hotplug operation.  in cpuhp_store_callbacks()
1963 	 * depending on the hotplug state of the cpu.  in __cpuhp_state_add_instance_cpuslocked()
2000  * __cpuhp_setup_state_cpuslocked - Setup the callbacks for an hotplug machine state
2047 	 * depending on the hotplug state of the cpu.  in __cpuhp_setup_state_cpuslocked()
2110 	 * on the hotplug state of the cpu. This function is not  in __cpuhp_state_remove_instance()
2131  * __cpuhp_remove_state_cpuslocked - Remove the callbacks for an hotplug machine state
2162 	 * on the hotplug state of the cpu. This function is not  in __cpuhp_remove_state_cpuslocked()
2221 		 * abusers of the hotplug machinery (thermal management).  in cpuhp_smt_disable()
2226 		 * called under the sysfs hotplug lock, so it is properly  in cpuhp_smt_disable()
2385 	.name = "hotplug",
2417 	.name = "hotplug",
2620 	 * regular CPU hotplug is properly serialized.  in set_cpu_online()
2624 	 * concurrent hotplug operations.  in set_cpu_online()