#ifndef _LINUX_STOP_MACHINE #define _LINUX_STOP_MACHINE #include <linux/cpu.h> #include <linux/cpumask.h> #include <linux/smp.h> #include <linux/list.h> #include <asm/system.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; void *arg; struct cpu_stop_done *done; }; int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg); void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, struct cpu_stop_work *work_buf); int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); #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 void 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); } } static inline int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg) { if (cpumask_test_cpu(raw_smp_processor_id(), cpumask)) return stop_one_cpu(raw_smp_processor_id(), fn, arg); return -ENOENT; } static inline int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg) { return stop_cpus(cpumask, fn, arg); } #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_STOP_MACHINE) && defined(CONFIG_SMP) /** * 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. */ int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus); /** * __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 is a special version of the above, which assumes cpus * won't come or go while it's being called. Used by hotplug cpu. */ int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus); int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data, const struct cpumask *cpus); #else /* CONFIG_STOP_MACHINE && CONFIG_SMP */ static inline int __stop_machine(int (*fn)(void *), 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 inline int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus) { return __stop_machine(fn, data, cpus); } static inline int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data, const struct cpumask *cpus) { return __stop_machine(fn, data, cpus); } #endif /* CONFIG_STOP_MACHINE && CONFIG_SMP */ #endif /* _LINUX_STOP_MACHINE */