| /* SPDX-License-Identifier: GPL-2.0 */ |
| #ifndef _LINUX_STOP_MACHINE |
| #define _LINUX_STOP_MACHINE |
| |
| #include <linux/cpu.h> |
| #include <linux/cpumask.h> |
| #include <linux/smp.h> |
| #include <linux/list.h> |
| |
| /* |
| * stop_cpu[s]() is simplistic per-cpu maximum priority cpu |
| * monopolization mechanism. The caller can specify a non-sleeping |
| * function to be executed on a single or multiple cpus preempting all |
| * other processes and monopolizing those cpus until it finishes. |
| * |
| * Resources for this mechanism are preallocated when a cpu is brought |
| * up and requests are guaranteed to be served as long as the target |
| * cpus are online. |
| */ |
| typedef int (*cpu_stop_fn_t)(void *arg); |
| |
| #ifdef CONFIG_SMP |
| |
| struct cpu_stop_work { |
| struct list_head list; /* cpu_stopper->works */ |
| cpu_stop_fn_t fn; |
| unsigned long caller; |
| void *arg; |
| struct cpu_stop_done *done; |
| }; |
| |
| int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg); |
| int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg); |
| bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, |
| struct cpu_stop_work *work_buf); |
| void stop_machine_park(int cpu); |
| void stop_machine_unpark(int cpu); |
| void stop_machine_yield(const struct cpumask *cpumask); |
| |
| extern void print_stop_info(const char *log_lvl, struct task_struct *task); |
| |
| #else /* CONFIG_SMP */ |
| |
| #include <linux/workqueue.h> |
| |
| struct cpu_stop_work { |
| struct work_struct work; |
| cpu_stop_fn_t fn; |
| void *arg; |
| }; |
| |
| static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg) |
| { |
| int ret = -ENOENT; |
| preempt_disable(); |
| if (cpu == smp_processor_id()) |
| ret = fn(arg); |
| preempt_enable(); |
| return ret; |
| } |
| |
| static void stop_one_cpu_nowait_workfn(struct work_struct *work) |
| { |
| struct cpu_stop_work *stwork = |
| container_of(work, struct cpu_stop_work, work); |
| preempt_disable(); |
| stwork->fn(stwork->arg); |
| preempt_enable(); |
| } |
| |
| static inline bool stop_one_cpu_nowait(unsigned int cpu, |
| cpu_stop_fn_t fn, void *arg, |
| struct cpu_stop_work *work_buf) |
| { |
| if (cpu == smp_processor_id()) { |
| INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn); |
| work_buf->fn = fn; |
| work_buf->arg = arg; |
| schedule_work(&work_buf->work); |
| return true; |
| } |
| |
| return false; |
| } |
| |
| static inline void print_stop_info(const char *log_lvl, struct task_struct *task) { } |
| |
| #endif /* CONFIG_SMP */ |
| |
| /* |
| * stop_machine "Bogolock": stop the entire machine, disable |
| * interrupts. This is a very heavy lock, which is equivalent to |
| * grabbing every spinlock (and more). So the "read" side to such a |
| * lock is anything which disables preemption. |
| */ |
| #if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU) |
| |
| /** |
| * stop_machine: freeze the machine on all CPUs and run this function |
| * @fn: the function to run |
| * @data: the data ptr for the @fn() |
| * @cpus: the cpus to run the @fn() on (NULL = any online cpu) |
| * |
| * Description: This causes a thread to be scheduled on every cpu, |
| * each of which disables interrupts. The result is that no one is |
| * holding a spinlock or inside any other preempt-disabled region when |
| * @fn() runs. |
| * |
| * This can be thought of as a very heavy write lock, equivalent to |
| * grabbing every spinlock in the kernel. |
| * |
| * Protects against CPU hotplug. |
| */ |
| int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus); |
| |
| /** |
| * stop_machine_cpuslocked: freeze the machine on all CPUs and run this function |
| * @fn: the function to run |
| * @data: the data ptr for the @fn() |
| * @cpus: the cpus to run the @fn() on (NULL = any online cpu) |
| * |
| * Same as above. Must be called from with in a cpus_read_lock() protected |
| * region. Avoids nested calls to cpus_read_lock(). |
| */ |
| int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus); |
| |
| int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, |
| const struct cpumask *cpus); |
| #else /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */ |
| |
| static __always_inline int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data, |
| const struct cpumask *cpus) |
| { |
| unsigned long flags; |
| int ret; |
| local_irq_save(flags); |
| ret = fn(data); |
| local_irq_restore(flags); |
| return ret; |
| } |
| |
| static __always_inline int |
| stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus) |
| { |
| return stop_machine_cpuslocked(fn, data, cpus); |
| } |
| |
| static __always_inline int |
| stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, |
| const struct cpumask *cpus) |
| { |
| return stop_machine(fn, data, cpus); |
| } |
| |
| #endif /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */ |
| #endif /* _LINUX_STOP_MACHINE */ |