stop_machine: add ALL_CPUS option (5c2aed62) · Commits · 戴 / test

include/linux/stop_machine.h

+7 −1

Original line number	Diff line number	Diff line
		@@ -8,11 +8,17 @@
		#include <asm/system.h>

		#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)

		#define ALL_CPUS ~0U

		/**
		* stop_machine_run: freeze the machine on all CPUs and run this function
		* @fn: the function to run
		* @data: the data ptr for the @fn()
		* @cpu: the cpu to run @fn() on (or any, if @cpu == NR_CPUS.
		* @cpu: if @cpu == n, run @fn() on cpu n
		* if @cpu == NR_CPUS, run @fn() on any cpu
		* if @cpu == ALL_CPUS, run @fn() first on the calling cpu, and then
		* concurrently on all the other cpus
		*
		* Description: This causes a thread to be scheduled on every other cpu,
		* each of which disables interrupts, and finally interrupts are disabled

kernel/stop_machine.c

+25 −7

Original line number	Diff line number	Diff line
		@@ -22,9 +22,17 @@ enum stopmachine_state {
		STOPMACHINE_WAIT,
		STOPMACHINE_PREPARE,
		STOPMACHINE_DISABLE_IRQ,
		STOPMACHINE_RUN,
		STOPMACHINE_EXIT,
		};

		struct stop_machine_data {
		int (fn)(void );
		void *data;
		struct completion done;
		int run_all;
		} smdata;

		static enum stopmachine_state stopmachine_state;
		static unsigned int stopmachine_num_threads;
		static atomic_t stopmachine_thread_ack;
		@@ -33,6 +41,7 @@ static int stopmachine(void *cpu)
		{
		int irqs_disabled = 0;
		int prepared = 0;
		int ran = 0;
		cpumask_of_cpu_ptr(cpumask, (int)(long)cpu);

		set_cpus_allowed_ptr(current, cpumask);
		@@ -58,6 +67,11 @@ static int stopmachine(void *cpu)
		prepared = 1;
		smp_mb(); /* Must read state first. */
		atomic_inc(&stopmachine_thread_ack);
		} else if (stopmachine_state == STOPMACHINE_RUN && !ran) {
		smdata.fn(smdata.data);
		ran = 1;
		smp_mb(); /* Must read state first. */
		atomic_inc(&stopmachine_thread_ack);
		}
		/* Yield in first stage: migration threads need to
		* help our sisters onto their CPUs. */
		@@ -136,11 +150,10 @@ static void restart_machine(void)
		preempt_enable_no_resched();
		}

		struct stop_machine_data {
		int (fn)(void );
		void *data;
		struct completion done;
		};
		static void run_other_cpus(void)
		{
		stopmachine_set_state(STOPMACHINE_RUN);
		}

		static int do_stop(void *_smdata)
		{
		@@ -150,6 +163,8 @@ static int do_stop(void *_smdata)
		ret = stop_machine();
		if (ret == 0) {
		ret = smdata->fn(smdata->data);
		if (smdata->run_all)
		run_other_cpus();
		restart_machine();
		}

		@@ -173,14 +188,17 @@ struct task_struct __stop_machine_run(int (fn)(void ), void data,
		struct stop_machine_data smdata;
		struct task_struct *p;

		mutex_lock(&stopmachine_mutex);

		smdata.fn = fn;
		smdata.data = data;
		smdata.run_all = (cpu == ALL_CPUS) ? 1 : 0;
		init_completion(&smdata.done);

		mutex_lock(&stopmachine_mutex);
		smp_wmb(); /* make sure other cpus see smdata updates */

		/* If they don't care which CPU fn runs on, bind to any online one. */
		if (cpu == NR_CPUS)
		if (cpu == NR_CPUS \|\| cpu == ALL_CPUS)
		cpu = raw_smp_processor_id();

		p = kthread_create(do_stop, &smdata, "kstopmachine");

Admin message