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Diffstat (limited to 'include/linux/stop_machine.h')
-rw-r--r-- | include/linux/stop_machine.h | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h new file mode 100644 index 000000000..ea7a74ea7 --- /dev/null +++ b/include/linux/stop_machine.h @@ -0,0 +1,172 @@ +/* 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); + +/** + * stop_core_cpuslocked: - stop all threads on just one core + * @cpu: any cpu in the targeted core + * @fn: the function to run + * @data: the data ptr for @fn() + * + * Same as above, but instead of every CPU, only the logical CPUs of a + * single core are affected. + * + * Context: Must be called from within a cpus_read_lock() protected region. + * + * Return: 0 if all executions of @fn returned 0, any non zero return + * value if any returned non zero. + */ +int stop_core_cpuslocked(unsigned int cpu, cpu_stop_fn_t fn, void *data); + +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 */ |