1 /* CPU control.
12 #include <linux/cpu.h>
52 	 * an ongoing cpu hotplug operation.
89  * Note that during a cpu-hotplug operation, the new readers, if any,
174 static inline void check_for_tasks(int cpu)  in check_for_tasks()  argument
180 		if (task_cpu(p) == cpu && p->state == TASK_RUNNING &&  in check_for_tasks()
182 			printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d "  in check_for_tasks()
184 				p->comm, task_pid_nr(p), cpu,  in check_for_tasks()
195 /* Take this CPU down. */
201 	/* Ensure this CPU doesn't handle any more interrupts. */  in take_cpu_down()
211 static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)  in _cpu_down()  argument
214 	void *hcpu = (void *)(long)cpu;  in _cpu_down()
224 	if (!cpu_online(cpu))  in _cpu_down()
233 		printk("%s: attempt to take down CPU %u failed\n",  in _cpu_down()
234 				__func__, cpu);  in _cpu_down()
238 	err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));  in _cpu_down()
240 		/* CPU didn't die: tell everyone.  Can't complain. */  in _cpu_down()
245 	BUG_ON(cpu_online(cpu));  in _cpu_down()
249 	 * runnable tasks from the cpu, there's only the idle task left now  in _cpu_down()
254 	while (!idle_cpu(cpu))  in _cpu_down()
257 	/* This actually kills the CPU. */  in _cpu_down()
258 	__cpu_die(cpu);  in _cpu_down()
260 	/* CPU is completely dead: tell everyone.  Too late to complain. */  in _cpu_down()
263 	check_for_tasks(cpu);  in _cpu_down()
272 int __ref cpu_down(unsigned int cpu)  in cpu_down()  argument
283 	err = _cpu_down(cpu, 0);  in cpu_down()
293 static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)  in _cpu_up()  argument
296 	void *hcpu = (void *)(long)cpu;  in _cpu_up()
299 	if (cpu_online(cpu) || !cpu_present(cpu))  in _cpu_up()
306 		printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n",  in _cpu_up()
307 				__func__, cpu);  in _cpu_up()
312 	ret = __cpu_up(cpu);  in _cpu_up()
315 	BUG_ON(!cpu_online(cpu));  in _cpu_up()
328 int __cpuinit cpu_up(unsigned int cpu)  in cpu_up()  argument
337 	if (!cpu_possible(cpu)) {  in cpu_up()
338 		printk(KERN_ERR "can't online cpu %d because it is not "  in cpu_up()
339 			"configured as may-hotadd at boot time\n", cpu);  in cpu_up()
348 	nid = cpu_to_node(cpu);  in cpu_up()
358 			"Can't online cpu %d due to NULL pgdat\n", cpu);  in cpu_up()
376 	err = _cpu_up(cpu, 0);  in cpu_up()
397 	int cpu, first_cpu, error = 0;  in disable_nonboot_cpus()  local
403 	 * with the userspace trying to use the CPU hotplug at the same time  in disable_nonboot_cpus()
409 	for_each_online_cpu(cpu) {  in disable_nonboot_cpus()
410 		if (cpu == first_cpu)  in disable_nonboot_cpus()
412 		error = _cpu_down(cpu, 1);  in disable_nonboot_cpus()
414 			cpumask_set_cpu(cpu, frozen_cpus);  in disable_nonboot_cpus()
416 			printk(KERN_ERR "Error taking CPU%d down: %d\n",  in disable_nonboot_cpus()
417 				cpu, error);  in disable_nonboot_cpus()
445 	int cpu, error;  in enable_nonboot_cpus()  local
447 	/* Allow everyone to use the CPU hotplug again */  in enable_nonboot_cpus()
457 	for_each_cpu(cpu, frozen_cpus) {  in enable_nonboot_cpus()
458 		error = _cpu_up(cpu, 1);  in enable_nonboot_cpus()
460 			printk(KERN_INFO "CPU%d is up\n", cpu);  in enable_nonboot_cpus()
463 		printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);  in enable_nonboot_cpus()
482  * Prevent regular CPU hotplug from racing with the freezer, by disabling CPU
484  * to continue until any currently running CPU hotplug operation gets
488  * CPU hotplug path and released only after it is complete. Thus, we
489  * (and hence the freezer) will block here until any currently running CPU
501  * When tasks have been thawed, re-enable regular CPU hotplug (which had been
512  * When callbacks for CPU hotplug notifications are being executed, we must
516  * Hence we need to prevent the freezer from racing with regular CPU hotplug.
518  * This synchronization is implemented by mutually excluding regular CPU
556  * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
557  * @cpu: cpu that just started
560  * It must be called by the arch code on the new cpu, before the new cpu
561  * enables interrupts and before the "boot" cpu returns from __cpu_up().
563 void __cpuinit notify_cpu_starting(unsigned int cpu)  in notify_cpu_starting()  argument
568 	if (frozen_cpus != NULL && cpumask_test_cpu(cpu, frozen_cpus))  in notify_cpu_starting()
571 	cpu_notify(val, (void *)(long)cpu);  in notify_cpu_starting()
580  * It is used by cpumask_of() to get a constant address to a CPU
625 void set_cpu_possible(unsigned int cpu, bool possible)  in set_cpu_possible()  argument
628 		cpumask_set_cpu(cpu, to_cpumask(cpu_possible_bits));  in set_cpu_possible()
630 		cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));  in set_cpu_possible()
633 void set_cpu_present(unsigned int cpu, bool present)  in set_cpu_present()  argument
636 		cpumask_set_cpu(cpu, to_cpumask(cpu_present_bits));  in set_cpu_present()
638 		cpumask_clear_cpu(cpu, to_cpumask(cpu_present_bits));  in set_cpu_present()
641 void set_cpu_online(unsigned int cpu, bool online)  in set_cpu_online()  argument
644 		cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits));  in set_cpu_online()
646 		cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits));  in set_cpu_online()
649 void set_cpu_active(unsigned int cpu, bool active)  in set_cpu_active()  argument
652 		cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));  in set_cpu_active()
654 		cpumask_clear_cpu(cpu, to_cpumask(cpu_active_bits));  in set_cpu_active()