#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/stop_machine.h>
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
-/* This protects CPUs going up and down... */
-DECLARE_MUTEX(cpucontrol);
-EXPORT_SYMBOL_GPL(cpucontrol);
+#ifdef CONFIG_SMP
+/* Serializes the updates to cpu_online_mask, cpu_present_mask */
+static DEFINE_MUTEX(cpu_add_remove_lock);
-static struct notifier_block *cpu_chain;
+static __cpuinitdata RAW_NOTIFIER_HEAD(cpu_chain);
-/*
- * Used to check by callers if they need to acquire the cpucontrol
- * or not to protect a cpu from being removed. Its sometimes required to
- * call these functions both for normal operations, and in response to
- * a cpu being added/removed. If the context of the call is in the same
- * thread context as a CPU hotplug thread, we dont need to take the lock
- * since its already protected
- * check drivers/cpufreq/cpufreq.c for its usage - Ashok Raj
+/* 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;
+
+static struct {
+ struct task_struct *active_writer;
+ struct mutex lock; /* Synchronizes accesses to refcount, */
+ /*
+ * Also blocks the new readers during
+ * an ongoing cpu hotplug operation.
+ */
+ int refcount;
+} cpu_hotplug = {
+ .active_writer = NULL,
+ .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
+ .refcount = 0,
+};
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+void get_online_cpus(void)
+{
+ might_sleep();
+ if (cpu_hotplug.active_writer == current)
+ return;
+ mutex_lock(&cpu_hotplug.lock);
+ cpu_hotplug.refcount++;
+ mutex_unlock(&cpu_hotplug.lock);
+
+}
+EXPORT_SYMBOL_GPL(get_online_cpus);
-int current_in_cpu_hotplug(void)
+void put_online_cpus(void)
{
- return (current->flags & PF_HOTPLUG_CPU);
+ if (cpu_hotplug.active_writer == current)
+ return;
+ mutex_lock(&cpu_hotplug.lock);
+ if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
+ wake_up_process(cpu_hotplug.active_writer);
+ mutex_unlock(&cpu_hotplug.lock);
+
+}
+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);
}
-EXPORT_SYMBOL_GPL(current_in_cpu_hotplug);
+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.
+ *
+ * Note that during a cpu-hotplug operation, the new readers, if any,
+ * will be blocked by the cpu_hotplug.lock
+ *
+ * Since cpu_hotplug_begin() is always called after invoking
+ * cpu_maps_update_begin(), we can be sure that only one writer is active.
+ *
+ * Note that theoretically, there is a possibility of a livelock:
+ * - Refcount goes to zero, last reader wakes up the sleeping
+ * writer.
+ * - Last reader unlocks the cpu_hotplug.lock.
+ * - A new reader arrives at this moment, bumps up the refcount.
+ * - The writer acquires the cpu_hotplug.lock finds the refcount
+ * non zero and goes to sleep again.
+ *
+ * However, this is very difficult to achieve in practice since
+ * get_online_cpus() not an api which is called all that often.
+ *
+ */
+static void cpu_hotplug_begin(void)
+{
+ cpu_hotplug.active_writer = current;
+
+ for (;;) {
+ mutex_lock(&cpu_hotplug.lock);
+ if (likely(!cpu_hotplug.refcount))
+ break;
+ __set_current_state(TASK_UNINTERRUPTIBLE);
+ mutex_unlock(&cpu_hotplug.lock);
+ schedule();
+ }
+}
+static void cpu_hotplug_done(void)
+{
+ cpu_hotplug.active_writer = NULL;
+ mutex_unlock(&cpu_hotplug.lock);
+}
/* Need to know about CPUs going up/down? */
-int register_cpu_notifier(struct notifier_block *nb)
+int __ref register_cpu_notifier(struct notifier_block *nb)
{
int ret;
-
- if ((ret = down_interruptible(&cpucontrol)) != 0)
- return ret;
- ret = notifier_chain_register(&cpu_chain, nb);
- up(&cpucontrol);
+ cpu_maps_update_begin();
+ ret = raw_notifier_chain_register(&cpu_chain, nb);
+ cpu_maps_update_done();
return ret;
}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
EXPORT_SYMBOL(register_cpu_notifier);
-void unregister_cpu_notifier(struct notifier_block *nb)
+void __ref unregister_cpu_notifier(struct notifier_block *nb)
{
- down(&cpucontrol);
- notifier_chain_unregister(&cpu_chain, nb);
- up(&cpucontrol);
+ cpu_maps_update_begin();
+ raw_notifier_chain_unregister(&cpu_chain, nb);
+ cpu_maps_update_done();
}
EXPORT_SYMBOL(unregister_cpu_notifier);
-#ifdef CONFIG_HOTPLUG_CPU
static inline void check_for_tasks(int cpu)
{
struct task_struct *p;
(!cputime_eq(p->utime, cputime_zero) ||
!cputime_eq(p->stime, cputime_zero)))
printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\
- (state = %ld, flags = %lx) \n",
- p->comm, p->pid, cpu, p->state, p->flags);
+ (state = %ld, flags = %x) \n",
+ p->comm, task_pid_nr(p), cpu,
+ p->state, p->flags);
}
write_unlock_irq(&tasklist_lock);
}
+struct take_cpu_down_param {
+ unsigned long mod;
+ void *hcpu;
+};
+
/* Take this CPU down. */
-static int take_cpu_down(void *unused)
+static int __ref take_cpu_down(void *_param)
{
+ struct take_cpu_down_param *param = _param;
int err;
/* Ensure this CPU doesn't handle any more interrupts. */
if (err < 0)
return err;
+ raw_notifier_call_chain(&cpu_chain, CPU_DYING | param->mod,
+ param->hcpu);
+
/* 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;
}
-int cpu_down(unsigned int cpu)
+/* Requires cpu_add_remove_lock to be held */
+static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
{
- int err;
- struct task_struct *p;
- cpumask_t old_allowed, tmp;
+ int err, nr_calls = 0;
+ cpumask_var_t old_allowed;
+ void *hcpu = (void *)(long)cpu;
+ unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
+ struct take_cpu_down_param tcd_param = {
+ .mod = mod,
+ .hcpu = hcpu,
+ };
- if ((err = lock_cpu_hotplug_interruptible()) != 0)
- return err;
+ if (num_online_cpus() == 1)
+ return -EBUSY;
- if (num_online_cpus() == 1) {
- err = -EBUSY;
- goto out;
- }
+ if (!cpu_online(cpu))
+ return -EINVAL;
- if (!cpu_online(cpu)) {
- err = -EINVAL;
- goto out;
- }
+ if (!alloc_cpumask_var(&old_allowed, GFP_KERNEL))
+ return -ENOMEM;
- /*
- * Leave a trace in current->flags indicating we are already in
- * process of performing CPU hotplug. Callers can check if cpucontrol
- * is already acquired by current thread, and if so not cause
- * a dead lock by not acquiring the lock
- */
- current->flags |= PF_HOTPLUG_CPU;
- err = notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
- (void *)(long)cpu);
+ cpu_hotplug_begin();
+ set_cpu_active(cpu, false);
+ err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod,
+ hcpu, -1, &nr_calls);
if (err == NOTIFY_BAD) {
+ set_cpu_active(cpu, true);
+
+ nr_calls--;
+ __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
+ hcpu, nr_calls, NULL);
printk("%s: attempt to take down CPU %u failed\n",
- __FUNCTION__, cpu);
+ __func__, cpu);
err = -EINVAL;
- goto out;
+ goto out_release;
}
/* Ensure that we are not runnable on dying cpu */
- old_allowed = current->cpus_allowed;
- tmp = CPU_MASK_ALL;
- cpu_clear(cpu, tmp);
- set_cpus_allowed(current, tmp);
+ cpumask_copy(old_allowed, ¤t->cpus_allowed);
+ set_cpus_allowed_ptr(current, cpu_active_mask);
- p = __stop_machine_run(take_cpu_down, NULL, cpu);
- if (IS_ERR(p)) {
+ 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. */
- if (notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
- (void *)(long)cpu) == NOTIFY_BAD)
+ if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
+ hcpu) == NOTIFY_BAD)
BUG();
- err = PTR_ERR(p);
goto out_allowed;
}
-
- if (cpu_online(cpu))
- goto out_thread;
+ BUG_ON(cpu_online(cpu));
/* Wait for it to sleep (leaving idle task). */
while (!idle_cpu(cpu))
/* This actually kills the CPU. */
__cpu_die(cpu);
- /* Move it here so it can run. */
- kthread_bind(p, get_cpu());
- put_cpu();
-
/* CPU is completely dead: tell everyone. Too late to complain. */
- if (notifier_call_chain(&cpu_chain, CPU_DEAD, (void *)(long)cpu)
- == NOTIFY_BAD)
+ if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD | mod,
+ hcpu) == NOTIFY_BAD)
BUG();
check_for_tasks(cpu);
-out_thread:
- err = kthread_stop(p);
out_allowed:
- set_cpus_allowed(current, old_allowed);
-out:
- current->flags &= ~PF_HOTPLUG_CPU;
- unlock_cpu_hotplug();
+ set_cpus_allowed_ptr(current, old_allowed);
+out_release:
+ cpu_hotplug_done();
+ if (!err) {
+ if (raw_notifier_call_chain(&cpu_chain, CPU_POST_DEAD | mod,
+ hcpu) == NOTIFY_BAD)
+ BUG();
+ }
+ free_cpumask_var(old_allowed);
return err;
}
-#endif /*CONFIG_HOTPLUG_CPU*/
-int __devinit cpu_up(unsigned int cpu)
+int __ref cpu_down(unsigned int cpu)
{
- int ret;
- void *hcpu = (void *)(long)cpu;
+ int err;
- if ((ret = down_interruptible(&cpucontrol)) != 0)
- return ret;
+ err = stop_machine_create();
+ if (err)
+ return err;
+ cpu_maps_update_begin();
- if (cpu_online(cpu) || !cpu_present(cpu)) {
- ret = -EINVAL;
+ if (cpu_hotplug_disabled) {
+ err = -EBUSY;
goto out;
}
- /*
- * Leave a trace in current->flags indicating we are already in
- * process of performing CPU hotplug.
- */
- current->flags |= PF_HOTPLUG_CPU;
- ret = notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);
+ err = _cpu_down(cpu, 0);
+
+out:
+ cpu_maps_update_done();
+ stop_machine_destroy();
+ return err;
+}
+EXPORT_SYMBOL(cpu_down);
+#endif /*CONFIG_HOTPLUG_CPU*/
+
+/* Requires cpu_add_remove_lock to be held */
+static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
+{
+ int ret, nr_calls = 0;
+ void *hcpu = (void *)(long)cpu;
+ unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
+
+ if (cpu_online(cpu) || !cpu_present(cpu))
+ return -EINVAL;
+
+ cpu_hotplug_begin();
+ ret = __raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE | mod, hcpu,
+ -1, &nr_calls);
if (ret == NOTIFY_BAD) {
+ nr_calls--;
printk("%s: attempt to bring up CPU %u failed\n",
- __FUNCTION__, cpu);
+ __func__, cpu);
ret = -EINVAL;
goto out_notify;
}
ret = __cpu_up(cpu);
if (ret != 0)
goto out_notify;
- if (!cpu_online(cpu))
- BUG();
+ BUG_ON(!cpu_online(cpu));
+
+ set_cpu_active(cpu, true);
/* Now call notifier in preparation. */
- notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
+ raw_notifier_call_chain(&cpu_chain, CPU_ONLINE | mod, hcpu);
out_notify:
if (ret != 0)
- notifier_call_chain(&cpu_chain, CPU_UP_CANCELED, hcpu);
-out:
- current->flags &= ~PF_HOTPLUG_CPU;
- up(&cpucontrol);
+ __raw_notifier_call_chain(&cpu_chain,
+ CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
+ cpu_hotplug_done();
+
return ret;
}
+
+int __cpuinit cpu_up(unsigned int cpu)
+{
+ int err = 0;
+ if (!cpu_possible(cpu)) {
+ printk(KERN_ERR "can't online cpu %d because it is not "
+ "configured as may-hotadd at boot time\n", cpu);
+#if defined(CONFIG_IA64) || defined(CONFIG_X86_64)
+ printk(KERN_ERR "please check additional_cpus= boot "
+ "parameter\n");
+#endif
+ return -EINVAL;
+ }
+
+ cpu_maps_update_begin();
+
+ if (cpu_hotplug_disabled) {
+ err = -EBUSY;
+ goto out;
+ }
+
+ err = _cpu_up(cpu, 0);
+
+out:
+ cpu_maps_update_done();
+ return err;
+}
+
+#ifdef CONFIG_PM_SLEEP_SMP
+static cpumask_var_t frozen_cpus;
+
+int disable_nonboot_cpus(void)
+{
+ int cpu, first_cpu, error;
+
+ error = stop_machine_create();
+ if (error)
+ return error;
+ cpu_maps_update_begin();
+ first_cpu = cpumask_first(cpu_online_mask);
+ /*
+ * We take down all of the non-boot CPUs in one shot to avoid races
+ * with the userspace trying to use the CPU hotplug at the same time
+ */
+ cpumask_clear(frozen_cpus);
+
+ printk("Disabling non-boot CPUs ...\n");
+ for_each_online_cpu(cpu) {
+ if (cpu == first_cpu)
+ continue;
+ error = _cpu_down(cpu, 1);
+ if (!error)
+ cpumask_set_cpu(cpu, frozen_cpus);
+ else {
+ printk(KERN_ERR "Error taking CPU%d down: %d\n",
+ cpu, error);
+ break;
+ }
+ }
+
+ if (!error) {
+ BUG_ON(num_online_cpus() > 1);
+ /* Make sure the CPUs won't be enabled by someone else */
+ cpu_hotplug_disabled = 1;
+ } else {
+ printk(KERN_ERR "Non-boot CPUs are not disabled\n");
+ }
+ cpu_maps_update_done();
+ stop_machine_destroy();
+ return error;
+}
+
+void __weak arch_enable_nonboot_cpus_begin(void)
+{
+}
+
+void __weak arch_enable_nonboot_cpus_end(void)
+{
+}
+
+void __ref enable_nonboot_cpus(void)
+{
+ int cpu, error;
+
+ /* Allow everyone to use the CPU hotplug again */
+ cpu_maps_update_begin();
+ cpu_hotplug_disabled = 0;
+ if (cpumask_empty(frozen_cpus))
+ goto out;
+
+ printk("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);
+ continue;
+ }
+ printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
+ }
+
+ arch_enable_nonboot_cpus_end();
+
+ cpumask_clear(frozen_cpus);
+out:
+ cpu_maps_update_done();
+}
+
+static int alloc_frozen_cpus(void)
+{
+ if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
+ return -ENOMEM;
+ return 0;
+}
+core_initcall(alloc_frozen_cpus);
+#endif /* CONFIG_PM_SLEEP_SMP */
+
+/**
+ * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
+ * @cpu: cpu that just started
+ *
+ * This function calls the cpu_chain notifiers with CPU_STARTING.
+ * It must be called by the arch code on the new cpu, before the new cpu
+ * enables interrupts and before the "boot" cpu returns from __cpu_up().
+ */
+void __cpuinit notify_cpu_starting(unsigned int cpu)
+{
+ unsigned long val = CPU_STARTING;
+
+#ifdef CONFIG_PM_SLEEP_SMP
+ if (frozen_cpus != NULL && cpumask_test_cpu(cpu, frozen_cpus))
+ val = CPU_STARTING_FROZEN;
+#endif /* CONFIG_PM_SLEEP_SMP */
+ raw_notifier_call_chain(&cpu_chain, val, (void *)(long)cpu);
+}
+
+#endif /* CONFIG_SMP */
+
+/*
+ * cpu_bit_bitmap[] is a special, "compressed" data structure that
+ * represents all NR_CPUS bits binary values of 1<<nr.
+ *
+ * It is used by cpumask_of() to get a constant address to a CPU
+ * mask value that has a single bit set only.
+ */
+
+/* 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_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)
+
+const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
+
+ MASK_DECLARE_8(0), MASK_DECLARE_8(8),
+ MASK_DECLARE_8(16), MASK_DECLARE_8(24),
+#if BITS_PER_LONG > 32
+ MASK_DECLARE_8(32), MASK_DECLARE_8(40),
+ MASK_DECLARE_8(48), MASK_DECLARE_8(56),
+#endif
+};
+EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
+
+const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
+EXPORT_SYMBOL(cpu_all_bits);
+
+#ifdef CONFIG_INIT_ALL_POSSIBLE
+static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly
+ = CPU_BITS_ALL;
+#else
+static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
+#endif
+const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
+EXPORT_SYMBOL(cpu_possible_mask);
+
+static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
+const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
+EXPORT_SYMBOL(cpu_online_mask);
+
+static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly;
+const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits);
+EXPORT_SYMBOL(cpu_present_mask);
+
+static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly;
+const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits);
+EXPORT_SYMBOL(cpu_active_mask);
+
+void set_cpu_possible(unsigned int cpu, bool possible)
+{
+ if (possible)
+ cpumask_set_cpu(cpu, to_cpumask(cpu_possible_bits));
+ else
+ cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits));
+}
+
+void set_cpu_present(unsigned int cpu, bool present)
+{
+ if (present)
+ cpumask_set_cpu(cpu, to_cpumask(cpu_present_bits));
+ else
+ cpumask_clear_cpu(cpu, to_cpumask(cpu_present_bits));
+}
+
+void set_cpu_online(unsigned int cpu, bool online)
+{
+ if (online)
+ cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits));
+ else
+ cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits));
+}
+
+void set_cpu_active(unsigned int cpu, bool active)
+{
+ if (active)
+ cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
+ else
+ cpumask_clear_cpu(cpu, to_cpumask(cpu_active_bits));
+}
+
+void init_cpu_present(const struct cpumask *src)
+{
+ cpumask_copy(to_cpumask(cpu_present_bits), src);
+}
+
+void init_cpu_possible(const struct cpumask *src)
+{
+ cpumask_copy(to_cpumask(cpu_possible_bits), src);
+}
+
+void init_cpu_online(const struct cpumask *src)
+{
+ cpumask_copy(to_cpumask(cpu_online_bits), src);
+}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff