From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- include/linux/stop_machine.h | 157 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 157 insertions(+) create mode 100644 include/linux/stop_machine.h (limited to 'include/linux/stop_machine.h') diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h new file mode 100644 index 000000000..d2abbdb8c --- /dev/null +++ b/include/linux/stop_machine.h @@ -0,0 +1,157 @@ +#ifndef _LINUX_STOP_MACHINE +#define _LINUX_STOP_MACHINE + +#include +#include +#include +#include + +/* + * 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); +int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, 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 + +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 */ -- cgit v1.2.3-54-g00ecf