#include <linux/sched.h>
#include <linux/unistd.h>
#include <linux/cpu.h>
-#include <linux/module.h>
+#include <linux/export.h>
#include <linux/kthread.h>
#include <linux/stop_machine.h>
#include <linux/mutex.h>
#include <linux/gfp.h>
+#include <linux/suspend.h>
#ifdef CONFIG_SMP
/* Serializes the updates to cpu_online_mask, cpu_present_mask */
static DEFINE_MUTEX(cpu_add_remove_lock);
-static __cpuinitdata RAW_NOTIFIER_HEAD(cpu_chain);
+/*
+ * The following two API's must be used when attempting
+ * to serialize the updates to cpu_online_mask, cpu_present_mask.
+ */
+void cpu_maps_update_begin(void)
+{
+ mutex_lock(&cpu_add_remove_lock);
+}
+
+void cpu_maps_update_done(void)
+{
+ mutex_unlock(&cpu_add_remove_lock);
+}
+
+static RAW_NOTIFIER_HEAD(cpu_chain);
/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
* Should always be manipulated under cpu_add_remove_lock
*/
static int cpu_hotplug_disabled;
+#ifdef CONFIG_HOTPLUG_CPU
+
static struct {
struct task_struct *active_writer;
struct mutex lock; /* Synchronizes accesses to refcount, */
.refcount = 0,
};
-#ifdef CONFIG_HOTPLUG_CPU
-
void get_online_cpus(void)
{
might_sleep();
}
EXPORT_SYMBOL_GPL(put_online_cpus);
-#endif /* CONFIG_HOTPLUG_CPU */
-
-/*
- * The following two API's must be used when attempting
- * to serialize the updates to cpu_online_mask, cpu_present_mask.
- */
-void cpu_maps_update_begin(void)
-{
- mutex_lock(&cpu_add_remove_lock);
-}
-
-void cpu_maps_update_done(void)
-{
- mutex_unlock(&cpu_add_remove_lock);
-}
-
/*
* This ensures that the hotplug operation can begin only when the
* refcount goes to zero.
cpu_hotplug.active_writer = NULL;
mutex_unlock(&cpu_hotplug.lock);
}
+
+#else /* #if CONFIG_HOTPLUG_CPU */
+static void cpu_hotplug_begin(void) {}
+static void cpu_hotplug_done(void) {}
+#endif /* #else #if CONFIG_HOTPLUG_CPU */
+
/* Need to know about CPUs going up/down? */
int __ref register_cpu_notifier(struct notifier_block *nb)
{
return __cpu_notify(val, v, -1, NULL);
}
+#ifdef CONFIG_HOTPLUG_CPU
+
static void cpu_notify_nofail(unsigned long val, void *v)
{
- int err;
-
- err = cpu_notify(val, v);
- BUG_ON(err);
+ BUG_ON(cpu_notify(val, v));
}
-
-#ifdef CONFIG_HOTPLUG_CPU
-
EXPORT_SYMBOL(register_cpu_notifier);
void __ref unregister_cpu_notifier(struct notifier_block *nb)
write_lock_irq(&tasklist_lock);
for_each_process(p) {
if (task_cpu(p) == cpu && p->state == TASK_RUNNING &&
- (!cputime_eq(p->utime, cputime_zero) ||
- !cputime_eq(p->stime, cputime_zero)))
+ (p->utime || p->stime))
printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d "
"(state = %ld, flags = %x)\n",
p->comm, task_pid_nr(p), cpu,
}
struct take_cpu_down_param {
- struct task_struct *caller;
unsigned long mod;
void *hcpu;
};
static int __ref take_cpu_down(void *_param)
{
struct take_cpu_down_param *param = _param;
- unsigned int cpu = (unsigned long)param->hcpu;
int err;
/* Ensure this CPU doesn't handle any more interrupts. */
return err;
cpu_notify(CPU_DYING | param->mod, param->hcpu);
-
- if (task_cpu(param->caller) == cpu)
- move_task_off_dead_cpu(cpu, param->caller);
- /* Force idle task to run as soon as we yield: it should
- immediately notice cpu is offline and die quickly. */
- sched_idle_next();
return 0;
}
void *hcpu = (void *)(long)cpu;
unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
struct take_cpu_down_param tcd_param = {
- .caller = current,
.mod = mod,
.hcpu = hcpu,
};
return -EINVAL;
cpu_hotplug_begin();
- set_cpu_active(cpu, false);
+
err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls);
if (err) {
- set_cpu_active(cpu, true);
-
nr_calls--;
__cpu_notify(CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL);
printk("%s: attempt to take down CPU %u failed\n",
err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
if (err) {
- set_cpu_active(cpu, true);
/* CPU didn't die: tell everyone. Can't complain. */
cpu_notify_nofail(CPU_DOWN_FAILED | mod, hcpu);
}
BUG_ON(cpu_online(cpu));
- /* Wait for it to sleep (leaving idle task). */
+ /*
+ * The migration_call() CPU_DYING callback will have removed all
+ * runnable tasks from the cpu, there's only the idle task left now
+ * that the migration thread is done doing the stop_machine thing.
+ *
+ * Wait for the stop thread to go away.
+ */
while (!idle_cpu(cpu))
- yield();
+ cpu_relax();
/* This actually kills the CPU. */
__cpu_die(cpu);
ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls);
if (ret) {
nr_calls--;
- printk("%s: attempt to bring up CPU %u failed\n",
+ printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n",
__func__, cpu);
goto out_notify;
}
goto out_notify;
BUG_ON(!cpu_online(cpu));
- set_cpu_active(cpu, true);
-
/* Now call notifier in preparation. */
cpu_notify(CPU_ONLINE | mod, hcpu);
cpu_maps_update_done();
return err;
}
+EXPORT_SYMBOL_GPL(cpu_up);
#ifdef CONFIG_PM_SLEEP_SMP
static cpumask_var_t frozen_cpus;
+void __weak arch_disable_nonboot_cpus_begin(void)
+{
+}
+
+void __weak arch_disable_nonboot_cpus_end(void)
+{
+}
+
int disable_nonboot_cpus(void)
{
- int cpu, first_cpu, error;
+ int cpu, first_cpu, error = 0;
cpu_maps_update_begin();
first_cpu = cpumask_first(cpu_online_mask);
* with the userspace trying to use the CPU hotplug at the same time
*/
cpumask_clear(frozen_cpus);
+ arch_disable_nonboot_cpus_begin();
printk("Disabling non-boot CPUs ...\n");
for_each_online_cpu(cpu) {
}
}
+ arch_disable_nonboot_cpus_end();
+
if (!error) {
BUG_ON(num_online_cpus() > 1);
/* Make sure the CPUs won't be enabled by someone else */
if (cpumask_empty(frozen_cpus))
goto out;
- printk("Enabling non-boot CPUs ...\n");
+ printk(KERN_INFO "Enabling non-boot CPUs ...\n");
arch_enable_nonboot_cpus_begin();
for_each_cpu(cpu, frozen_cpus) {
error = _cpu_up(cpu, 1);
if (!error) {
- printk("CPU%d is up\n", cpu);
+ printk(KERN_INFO "CPU%d is up\n", cpu);
continue;
}
printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
cpu_maps_update_done();
}
-static int alloc_frozen_cpus(void)
+static int __init alloc_frozen_cpus(void)
{
if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
return -ENOMEM;
return 0;
}
core_initcall(alloc_frozen_cpus);
+
+/*
+ * Prevent regular CPU hotplug from racing with the freezer, by disabling CPU
+ * hotplug when tasks are about to be frozen. Also, don't allow the freezer
+ * to continue until any currently running CPU hotplug operation gets
+ * completed.
+ * To modify the 'cpu_hotplug_disabled' flag, we need to acquire the
+ * 'cpu_add_remove_lock'. And this same lock is also taken by the regular
+ * CPU hotplug path and released only after it is complete. Thus, we
+ * (and hence the freezer) will block here until any currently running CPU
+ * hotplug operation gets completed.
+ */
+void cpu_hotplug_disable_before_freeze(void)
+{
+ cpu_maps_update_begin();
+ cpu_hotplug_disabled = 1;
+ cpu_maps_update_done();
+}
+
+
+/*
+ * When tasks have been thawed, re-enable regular CPU hotplug (which had been
+ * disabled while beginning to freeze tasks).
+ */
+void cpu_hotplug_enable_after_thaw(void)
+{
+ cpu_maps_update_begin();
+ cpu_hotplug_disabled = 0;
+ cpu_maps_update_done();
+}
+
+/*
+ * When callbacks for CPU hotplug notifications are being executed, we must
+ * ensure that the state of the system with respect to the tasks being frozen
+ * or not, as reported by the notification, remains unchanged *throughout the
+ * duration* of the execution of the callbacks.
+ * Hence we need to prevent the freezer from racing with regular CPU hotplug.
+ *
+ * This synchronization is implemented by mutually excluding regular CPU
+ * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
+ * Hibernate notifications.
+ */
+static int
+cpu_hotplug_pm_callback(struct notifier_block *nb,
+ unsigned long action, void *ptr)
+{
+ switch (action) {
+
+ case PM_SUSPEND_PREPARE:
+ case PM_HIBERNATION_PREPARE:
+ cpu_hotplug_disable_before_freeze();
+ break;
+
+ case PM_POST_SUSPEND:
+ case PM_POST_HIBERNATION:
+ cpu_hotplug_enable_after_thaw();
+ break;
+
+ default:
+ return NOTIFY_DONE;
+ }
+
+ return NOTIFY_OK;
+}
+
+
+static int __init cpu_hotplug_pm_sync_init(void)
+{
+ pm_notifier(cpu_hotplug_pm_callback, 0);
+ return 0;
+}
+core_initcall(cpu_hotplug_pm_sync_init);
+
#endif /* CONFIG_PM_SLEEP_SMP */
/**
*/
/* cpu_bit_bitmap[0] is empty - so we can back into it */
-#define MASK_DECLARE_1(x) [x+1][0] = 1UL << (x)
+#define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x))
#define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
#define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
#define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
projects / linux-flexiantxendom0-3.2.10.git / blobdiff