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