diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/cpuhotplug.h | 132 |
1 files changed, 110 insertions, 22 deletions
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index 39cf84a30b9f..832d8a74fa59 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -22,8 +22,42 @@ * AP_ACTIVE AP_ACTIVE */ +/* + * CPU hotplug states. The state machine invokes the installed state + * startup callbacks sequentially from CPUHP_OFFLINE + 1 to CPUHP_ONLINE + * during a CPU online operation. During a CPU offline operation the + * installed teardown callbacks are invoked in the reverse order from + * CPU_ONLINE - 1 down to CPUHP_OFFLINE. + * + * The state space has three sections: PREPARE, STARTING and ONLINE. + * + * PREPARE: The callbacks are invoked on a control CPU before the + * hotplugged CPU is started up or after the hotplugged CPU has died. + * + * STARTING: The callbacks are invoked on the hotplugged CPU from the low level + * hotplug startup/teardown code with interrupts disabled. + * + * ONLINE: The callbacks are invoked on the hotplugged CPU from the per CPU + * hotplug thread with interrupts and preemption enabled. + * + * Adding explicit states to this enum is only necessary when: + * + * 1) The state is within the STARTING section + * + * 2) The state has ordering constraints vs. other states in the + * same section. + * + * If neither #1 nor #2 apply, please use the dynamic state space when + * setting up a state by using CPUHP_PREPARE_DYN or CPUHP_PREPARE_ONLINE + * for the @state argument of the setup function. + * + * See Documentation/core-api/cpu_hotplug.rst for further information and + * examples. + */ enum cpuhp_state { CPUHP_INVALID = -1, + + /* PREPARE section invoked on a control CPU */ CPUHP_OFFLINE = 0, CPUHP_CREATE_THREADS, CPUHP_PERF_PREPARE, @@ -95,6 +129,11 @@ enum cpuhp_state { CPUHP_BP_PREPARE_DYN, CPUHP_BP_PREPARE_DYN_END = CPUHP_BP_PREPARE_DYN + 20, CPUHP_BRINGUP_CPU, + + /* + * STARTING section invoked on the hotplugged CPU in low level + * bringup and teardown code. + */ CPUHP_AP_IDLE_DEAD, CPUHP_AP_OFFLINE, CPUHP_AP_SCHED_STARTING, @@ -155,6 +194,8 @@ enum cpuhp_state { CPUHP_AP_ARM_CACHE_B15_RAC_DYING, CPUHP_AP_ONLINE, CPUHP_TEARDOWN_CPU, + + /* Online section invoked on the hotplugged CPU from the hotplug thread */ CPUHP_AP_ONLINE_IDLE, CPUHP_AP_SCHED_WAIT_EMPTY, CPUHP_AP_SMPBOOT_THREADS, @@ -216,14 +257,15 @@ int __cpuhp_setup_state_cpuslocked(enum cpuhp_state state, const char *name, int (*teardown)(unsigned int cpu), bool multi_instance); /** - * cpuhp_setup_state - Setup hotplug state callbacks with calling the callbacks + * cpuhp_setup_state - Setup hotplug state callbacks with calling the @startup + * callback * @state: The state for which the calls are installed * @name: Name of the callback (will be used in debug output) - * @startup: startup callback function - * @teardown: teardown callback function + * @startup: startup callback function or NULL if not required + * @teardown: teardown callback function or NULL if not required * - * Installs the callback functions and invokes the startup callback on - * the present cpus which have already reached the @state. + * Installs the callback functions and invokes the @startup callback on + * the online cpus which have already reached the @state. */ static inline int cpuhp_setup_state(enum cpuhp_state state, const char *name, @@ -233,6 +275,18 @@ static inline int cpuhp_setup_state(enum cpuhp_state state, return __cpuhp_setup_state(state, name, true, startup, teardown, false); } +/** + * cpuhp_setup_state_cpuslocked - Setup hotplug state callbacks with calling + * @startup callback from a cpus_read_lock() + * held region + * @state: The state for which the calls are installed + * @name: Name of the callback (will be used in debug output) + * @startup: startup callback function or NULL if not required + * @teardown: teardown callback function or NULL if not required + * + * Same as cpuhp_setup_state() except that it must be invoked from within a + * cpus_read_lock() held region. + */ static inline int cpuhp_setup_state_cpuslocked(enum cpuhp_state state, const char *name, int (*startup)(unsigned int cpu), @@ -244,14 +298,14 @@ static inline int cpuhp_setup_state_cpuslocked(enum cpuhp_state state, /** * cpuhp_setup_state_nocalls - Setup hotplug state callbacks without calling the - * callbacks + * @startup callback * @state: The state for which the calls are installed * @name: Name of the callback. - * @startup: startup callback function - * @teardown: teardown callback function + * @startup: startup callback function or NULL if not required + * @teardown: teardown callback function or NULL if not required * - * Same as @cpuhp_setup_state except that no calls are executed are invoked - * during installation of this callback. NOP if SMP=n or HOTPLUG_CPU=n. + * Same as cpuhp_setup_state() except that the @startup callback is not + * invoked during installation. NOP if SMP=n or HOTPLUG_CPU=n. */ static inline int cpuhp_setup_state_nocalls(enum cpuhp_state state, const char *name, @@ -262,6 +316,19 @@ static inline int cpuhp_setup_state_nocalls(enum cpuhp_state state, false); } +/** + * cpuhp_setup_state_nocalls_cpuslocked - Setup hotplug state callbacks without + * invoking the @startup callback from + * a cpus_read_lock() held region + * callbacks + * @state: The state for which the calls are installed + * @name: Name of the callback. + * @startup: startup callback function or NULL if not required + * @teardown: teardown callback function or NULL if not required + * + * Same as cpuhp_setup_state_nocalls() except that it must be invoked from + * within a cpus_read_lock() held region. + */ static inline int cpuhp_setup_state_nocalls_cpuslocked(enum cpuhp_state state, const char *name, int (*startup)(unsigned int cpu), @@ -275,13 +342,13 @@ static inline int cpuhp_setup_state_nocalls_cpuslocked(enum cpuhp_state state, * cpuhp_setup_state_multi - Add callbacks for multi state * @state: The state for which the calls are installed * @name: Name of the callback. - * @startup: startup callback function - * @teardown: teardown callback function + * @startup: startup callback function or NULL if not required + * @teardown: teardown callback function or NULL if not required * * Sets the internal multi_instance flag and prepares a state to work as a multi * instance callback. No callbacks are invoked at this point. The callbacks are * invoked once an instance for this state are registered via - * @cpuhp_state_add_instance or @cpuhp_state_add_instance_nocalls. + * cpuhp_state_add_instance() or cpuhp_state_add_instance_nocalls() */ static inline int cpuhp_setup_state_multi(enum cpuhp_state state, const char *name, @@ -306,9 +373,10 @@ int __cpuhp_state_add_instance_cpuslocked(enum cpuhp_state state, * @state: The state for which the instance is installed * @node: The node for this individual state. * - * Installs the instance for the @state and invokes the startup callback on - * the present cpus which have already reached the @state. The @state must have - * been earlier marked as multi-instance by @cpuhp_setup_state_multi. + * Installs the instance for the @state and invokes the registered startup + * callback on the online cpus which have already reached the @state. The + * @state must have been earlier marked as multi-instance by + * cpuhp_setup_state_multi(). */ static inline int cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node) @@ -322,8 +390,9 @@ static inline int cpuhp_state_add_instance(enum cpuhp_state state, * @state: The state for which the instance is installed * @node: The node for this individual state. * - * Installs the instance for the @state The @state must have been earlier - * marked as multi-instance by @cpuhp_setup_state_multi. + * Installs the instance for the @state. The @state must have been earlier + * marked as multi-instance by cpuhp_setup_state_multi. NOP if SMP=n or + * HOTPLUG_CPU=n. */ static inline int cpuhp_state_add_instance_nocalls(enum cpuhp_state state, struct hlist_node *node) @@ -331,6 +400,17 @@ static inline int cpuhp_state_add_instance_nocalls(enum cpuhp_state state, return __cpuhp_state_add_instance(state, node, false); } +/** + * cpuhp_state_add_instance_nocalls_cpuslocked - Add an instance for a state + * without invoking the startup + * callback from a cpus_read_lock() + * held region. + * @state: The state for which the instance is installed + * @node: The node for this individual state. + * + * Same as cpuhp_state_add_instance_nocalls() except that it must be + * invoked from within a cpus_read_lock() held region. + */ static inline int cpuhp_state_add_instance_nocalls_cpuslocked(enum cpuhp_state state, struct hlist_node *node) @@ -346,7 +426,7 @@ void __cpuhp_remove_state_cpuslocked(enum cpuhp_state state, bool invoke); * @state: The state for which the calls are removed * * Removes the callback functions and invokes the teardown callback on - * the present cpus which have already reached the @state. + * the online cpus which have already reached the @state. */ static inline void cpuhp_remove_state(enum cpuhp_state state) { @@ -355,7 +435,7 @@ static inline void cpuhp_remove_state(enum cpuhp_state state) /** * cpuhp_remove_state_nocalls - Remove hotplug state callbacks without invoking - * teardown + * the teardown callback * @state: The state for which the calls are removed */ static inline void cpuhp_remove_state_nocalls(enum cpuhp_state state) @@ -363,6 +443,14 @@ static inline void cpuhp_remove_state_nocalls(enum cpuhp_state state) __cpuhp_remove_state(state, false); } +/** + * cpuhp_remove_state_nocalls_cpuslocked - Remove hotplug state callbacks without invoking + * teardown from a cpus_read_lock() held region. + * @state: The state for which the calls are removed + * + * Same as cpuhp_remove_state nocalls() except that it must be invoked + * from within a cpus_read_lock() held region. + */ static inline void cpuhp_remove_state_nocalls_cpuslocked(enum cpuhp_state state) { __cpuhp_remove_state_cpuslocked(state, false); @@ -390,8 +478,8 @@ int __cpuhp_state_remove_instance(enum cpuhp_state state, * @state: The state from which the instance is removed * @node: The node for this individual state. * - * Removes the instance and invokes the teardown callback on the present cpus - * which have already reached the @state. + * Removes the instance and invokes the teardown callback on the online cpus + * which have already reached @state. */ static inline int cpuhp_state_remove_instance(enum cpuhp_state state, struct hlist_node *node) |