#include <linux/stop_machine.h>
#include <linux/mutex.h>
-/* This protects CPUs going up and down... */
+/*
+ * Represents all cpu's present in the system
+ * In systems capable of hotplug, this map could dynamically grow
+ * as new cpu's are detected in the system via any platform specific
+ * method, such as ACPI for e.g.
+ */
+cpumask_t cpu_present_map __read_mostly;
+EXPORT_SYMBOL(cpu_present_map);
+
+#ifndef CONFIG_SMP
+
+/*
+ * Represents all cpu's that are currently online.
+ */
+cpumask_t cpu_online_map __read_mostly = CPU_MASK_ALL;
+EXPORT_SYMBOL(cpu_online_map);
+
+cpumask_t cpu_possible_map __read_mostly = CPU_MASK_ALL;
+EXPORT_SYMBOL(cpu_possible_map);
+
+#else /* CONFIG_SMP */
+
+/* Serializes the updates to cpu_online_map, cpu_present_map */
static DEFINE_MUTEX(cpu_add_remove_lock);
-static DEFINE_MUTEX(cpu_bitmask_lock);
static __cpuinitdata RAW_NOTIFIER_HEAD(cpu_chain);
*/
static int cpu_hotplug_disabled;
-#ifdef CONFIG_HOTPLUG_CPU
+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;
+
+void __init cpu_hotplug_init(void)
+{
+ cpu_hotplug.active_writer = NULL;
+ mutex_init(&cpu_hotplug.lock);
+ cpu_hotplug.refcount = 0;
+}
-/* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */
-static struct task_struct *recursive;
-static int recursive_depth;
+cpumask_t cpu_active_map;
-void lock_cpu_hotplug(void)
+#ifdef CONFIG_HOTPLUG_CPU
+
+void get_online_cpus(void)
{
- struct task_struct *tsk = current;
-
- if (tsk == recursive) {
- static int warnings = 10;
- if (warnings) {
- printk(KERN_ERR "Lukewarm IQ detected in hotplug locking\n");
- WARN_ON(1);
- warnings--;
- }
- recursive_depth++;
+ might_sleep();
+ if (cpu_hotplug.active_writer == current)
return;
- }
- mutex_lock(&cpu_bitmask_lock);
- recursive = tsk;
+ mutex_lock(&cpu_hotplug.lock);
+ cpu_hotplug.refcount++;
+ mutex_unlock(&cpu_hotplug.lock);
+
}
-EXPORT_SYMBOL_GPL(lock_cpu_hotplug);
+EXPORT_SYMBOL_GPL(get_online_cpus);
-void unlock_cpu_hotplug(void)
+void put_online_cpus(void)
{
- WARN_ON(recursive != current);
- if (recursive_depth) {
- recursive_depth--;
+ if (cpu_hotplug.active_writer == current)
return;
- }
- recursive = NULL;
- mutex_unlock(&cpu_bitmask_lock);
+ 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(unlock_cpu_hotplug);
+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_map, cpu_present_map.
+ */
+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.
+ *
+ * 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 __cpuinit register_cpu_notifier(struct notifier_block *nb)
+int __ref register_cpu_notifier(struct notifier_block *nb)
{
int ret;
- mutex_lock(&cpu_add_remove_lock);
+ cpu_maps_update_begin();
ret = raw_notifier_chain_register(&cpu_chain, nb);
- mutex_unlock(&cpu_add_remove_lock);
+ cpu_maps_update_done();
return ret;
}
EXPORT_SYMBOL(register_cpu_notifier);
-void unregister_cpu_notifier(struct notifier_block *nb)
+void __ref unregister_cpu_notifier(struct notifier_block *nb)
{
- mutex_lock(&cpu_add_remove_lock);
+ cpu_maps_update_begin();
raw_notifier_chain_unregister(&cpu_chain, nb);
- mutex_unlock(&cpu_add_remove_lock);
+ cpu_maps_update_done();
}
EXPORT_SYMBOL(unregister_cpu_notifier);
!cputime_eq(p->stime, cputime_zero)))
printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\
(state = %ld, flags = %x) \n",
- p->comm, p->pid, cpu, p->state, p->flags);
+ p->comm, task_pid_nr(p), cpu,
+ p->state, p->flags);
}
write_unlock_irq(&tasklist_lock);
}
};
/* Take this CPU down. */
-static int take_cpu_down(void *_param)
+static int __ref take_cpu_down(void *_param)
{
struct take_cpu_down_param *param = _param;
int err;
}
/* Requires cpu_add_remove_lock to be held */
-static int _cpu_down(unsigned int cpu, int tasks_frozen)
+static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
{
int err, nr_calls = 0;
struct task_struct *p;
if (!cpu_online(cpu))
return -EINVAL;
- raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
+ cpu_hotplug_begin();
err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod,
hcpu, -1, &nr_calls);
if (err == NOTIFY_BAD) {
__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_release;
}
/* Ensure that we are not runnable on dying cpu */
old_allowed = current->cpus_allowed;
- tmp = CPU_MASK_ALL;
+ cpus_setall(tmp);
cpu_clear(cpu, tmp);
- set_cpus_allowed(current, tmp);
+ set_cpus_allowed_ptr(current, &tmp);
- mutex_lock(&cpu_bitmask_lock);
p = __stop_machine_run(take_cpu_down, &tcd_param, cpu);
- mutex_unlock(&cpu_bitmask_lock);
if (IS_ERR(p) || cpu_online(cpu)) {
/* CPU didn't die: tell everyone. Can't complain. */
out_thread:
err = kthread_stop(p);
out_allowed:
- set_cpus_allowed(current, old_allowed);
+ set_cpus_allowed_ptr(current, &old_allowed);
out_release:
- raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE, hcpu);
+ cpu_hotplug_done();
+ if (!err) {
+ if (raw_notifier_call_chain(&cpu_chain, CPU_POST_DEAD | mod,
+ hcpu) == NOTIFY_BAD)
+ BUG();
+ }
return err;
}
-int cpu_down(unsigned int cpu)
+int __ref cpu_down(unsigned int cpu)
{
int err = 0;
- mutex_lock(&cpu_add_remove_lock);
- if (cpu_hotplug_disabled)
+ cpu_maps_update_begin();
+
+ if (cpu_hotplug_disabled) {
err = -EBUSY;
- else
- err = _cpu_down(cpu, 0);
+ goto out;
+ }
- mutex_unlock(&cpu_add_remove_lock);
+ cpu_clear(cpu, cpu_active_map);
+
+ /*
+ * Make sure the all cpus did the reschedule and are not
+ * using stale version of the cpu_active_map.
+ * This is not strictly necessary becuase stop_machine()
+ * that we run down the line already provides the required
+ * synchronization. But it's really a side effect and we do not
+ * want to depend on the innards of the stop_machine here.
+ */
+ synchronize_sched();
+
+ err = _cpu_down(cpu, 0);
+
+ if (cpu_online(cpu))
+ cpu_set(cpu, cpu_active_map);
+
+out:
+ cpu_maps_update_done();
return err;
}
+EXPORT_SYMBOL(cpu_down);
#endif /*CONFIG_HOTPLUG_CPU*/
/* Requires cpu_add_remove_lock to be held */
if (cpu_online(cpu) || !cpu_present(cpu))
return -EINVAL;
- raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
+ 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;
}
/* Arch-specific enabling code. */
- mutex_lock(&cpu_bitmask_lock);
ret = __cpu_up(cpu);
- mutex_unlock(&cpu_bitmask_lock);
if (ret != 0)
goto out_notify;
BUG_ON(!cpu_online(cpu));
if (ret != 0)
__raw_notifier_call_chain(&cpu_chain,
CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
- raw_notifier_call_chain(&cpu_chain, CPU_LOCK_RELEASE, hcpu);
+ cpu_hotplug_done();
return ret;
}
int __cpuinit cpu_up(unsigned int cpu)
{
int err = 0;
+ if (!cpu_isset(cpu, cpu_possible_map)) {
+ 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) || defined(CONFIG_S390)
+ printk(KERN_ERR "please check additional_cpus= boot "
+ "parameter\n");
+#endif
+ return -EINVAL;
+ }
- mutex_lock(&cpu_add_remove_lock);
- if (cpu_hotplug_disabled)
+ cpu_maps_update_begin();
+
+ if (cpu_hotplug_disabled) {
err = -EBUSY;
- else
- err = _cpu_up(cpu, 0);
+ goto out;
+ }
- mutex_unlock(&cpu_add_remove_lock);
+ err = _cpu_up(cpu, 0);
+
+ if (cpu_online(cpu))
+ cpu_set(cpu, cpu_active_map);
+
+out:
+ cpu_maps_update_done();
return err;
}
{
int cpu, first_cpu, error = 0;
- mutex_lock(&cpu_add_remove_lock);
+ cpu_maps_update_begin();
first_cpu = first_cpu(cpu_online_map);
/* 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
} else {
printk(KERN_ERR "Non-boot CPUs are not disabled\n");
}
- mutex_unlock(&cpu_add_remove_lock);
+ cpu_maps_update_done();
return error;
}
-void enable_nonboot_cpus(void)
+void __ref enable_nonboot_cpus(void)
{
int cpu, error;
/* Allow everyone to use the CPU hotplug again */
- mutex_lock(&cpu_add_remove_lock);
+ cpu_maps_update_begin();
cpu_hotplug_disabled = 0;
if (cpus_empty(frozen_cpus))
goto out;
printk("Enabling non-boot CPUs ...\n");
- for_each_cpu_mask(cpu, frozen_cpus) {
+ for_each_cpu_mask_nr(cpu, frozen_cpus) {
error = _cpu_up(cpu, 1);
if (!error) {
printk("CPU%d is up\n", cpu);
}
cpus_clear(frozen_cpus);
out:
- mutex_unlock(&cpu_add_remove_lock);
+ cpu_maps_update_done();
}
#endif /* CONFIG_PM_SLEEP_SMP */
+
+#endif /* CONFIG_SMP */
+
+/* 64 bits of zeros, for initializers. */
+#if BITS_PER_LONG == 32
+#define Z64 0, 0
+#else
+#define Z64 0
+#endif
+
+/* Initializer macros. */
+#define CMI0(n) { .bits = { 1UL << (n) } }
+#define CMI(n, ...) { .bits = { __VA_ARGS__, 1UL << ((n) % BITS_PER_LONG) } }
+
+#define CMI8(n, ...) \
+ CMI((n), __VA_ARGS__), CMI((n)+1, __VA_ARGS__), \
+ CMI((n)+2, __VA_ARGS__), CMI((n)+3, __VA_ARGS__), \
+ CMI((n)+4, __VA_ARGS__), CMI((n)+5, __VA_ARGS__), \
+ CMI((n)+6, __VA_ARGS__), CMI((n)+7, __VA_ARGS__)
+
+#if BITS_PER_LONG == 32
+#define CMI64(n, ...) \
+ CMI8((n), __VA_ARGS__), CMI8((n)+8, __VA_ARGS__), \
+ CMI8((n)+16, __VA_ARGS__), CMI8((n)+24, __VA_ARGS__), \
+ CMI8((n)+32, 0, __VA_ARGS__), CMI8((n)+40, 0, __VA_ARGS__), \
+ CMI8((n)+48, 0, __VA_ARGS__), CMI8((n)+56, 0, __VA_ARGS__)
+#else
+#define CMI64(n, ...) \
+ CMI8((n), __VA_ARGS__), CMI8((n)+8, __VA_ARGS__), \
+ CMI8((n)+16, __VA_ARGS__), CMI8((n)+24, __VA_ARGS__), \
+ CMI8((n)+32, __VA_ARGS__), CMI8((n)+40, __VA_ARGS__), \
+ CMI8((n)+48, __VA_ARGS__), CMI8((n)+56, __VA_ARGS__)
+#endif
+
+#define CMI256(n, ...) \
+ CMI64((n), __VA_ARGS__), CMI64((n)+64, Z64, __VA_ARGS__), \
+ CMI64((n)+128, Z64, Z64, __VA_ARGS__), \
+ CMI64((n)+192, Z64, Z64, Z64, __VA_ARGS__)
+#define Z256 Z64, Z64, Z64, Z64
+
+#define CMI1024(n, ...) \
+ CMI256((n), __VA_ARGS__), \
+ CMI256((n)+256, Z256, __VA_ARGS__), \
+ CMI256((n)+512, Z256, Z256, __VA_ARGS__), \
+ CMI256((n)+768, Z256, Z256, Z256, __VA_ARGS__)
+#define Z1024 Z256, Z256, Z256, Z256
+
+/* We want this statically initialized, just to be safe. We try not
+ * to waste too much space, either. */
+static const cpumask_t cpumask_map[]
+#ifdef CONFIG_HAVE_CPUMASK_OF_CPU_MAP
+__initdata
+#endif
+= {
+ CMI0(0), CMI0(1), CMI0(2), CMI0(3),
+#if NR_CPUS > 4
+ CMI0(4), CMI0(5), CMI0(6), CMI0(7),
+#endif
+#if NR_CPUS > 8
+ CMI0(8), CMI0(9), CMI0(10), CMI0(11),
+ CMI0(12), CMI0(13), CMI0(14), CMI0(15),
+#endif
+#if NR_CPUS > 16
+ CMI0(16), CMI0(17), CMI0(18), CMI0(19),
+ CMI0(20), CMI0(21), CMI0(22), CMI0(23),
+ CMI0(24), CMI0(25), CMI0(26), CMI0(27),
+ CMI0(28), CMI0(29), CMI0(30), CMI0(31),
+#endif
+#if NR_CPUS > 32
+#if BITS_PER_LONG == 32
+ CMI(32, 0), CMI(33, 0), CMI(34, 0), CMI(35, 0),
+ CMI(36, 0), CMI(37, 0), CMI(38, 0), CMI(39, 0),
+ CMI(40, 0), CMI(41, 0), CMI(42, 0), CMI(43, 0),
+ CMI(44, 0), CMI(45, 0), CMI(46, 0), CMI(47, 0),
+ CMI(48, 0), CMI(49, 0), CMI(50, 0), CMI(51, 0),
+ CMI(52, 0), CMI(53, 0), CMI(54, 0), CMI(55, 0),
+ CMI(56, 0), CMI(57, 0), CMI(58, 0), CMI(59, 0),
+ CMI(60, 0), CMI(61, 0), CMI(62, 0), CMI(63, 0),
+#else
+ CMI0(32), CMI0(33), CMI0(34), CMI0(35),
+ CMI0(36), CMI0(37), CMI0(38), CMI0(39),
+ CMI0(40), CMI0(41), CMI0(42), CMI0(43),
+ CMI0(44), CMI0(45), CMI0(46), CMI0(47),
+ CMI0(48), CMI0(49), CMI0(50), CMI0(51),
+ CMI0(52), CMI0(53), CMI0(54), CMI0(55),
+ CMI0(56), CMI0(57), CMI0(58), CMI0(59),
+ CMI0(60), CMI0(61), CMI0(62), CMI0(63),
+#endif /* BITS_PER_LONG == 64 */
+#endif
+#if NR_CPUS > 64
+ CMI64(64, Z64),
+#endif
+#if NR_CPUS > 128
+ CMI64(128, Z64, Z64), CMI64(192, Z64, Z64, Z64),
+#endif
+#if NR_CPUS > 256
+ CMI256(256, Z256),
+#endif
+#if NR_CPUS > 512
+ CMI256(512, Z256, Z256), CMI256(768, Z256, Z256, Z256),
+#endif
+#if NR_CPUS > 1024
+ CMI1024(1024, Z1024),
+#endif
+#if NR_CPUS > 2048
+ CMI1024(2048, Z1024, Z1024), CMI1024(3072, Z1024, Z1024, Z1024),
+#endif
+#if NR_CPUS > 4096
+#error NR_CPUS too big. Fix initializers or set CONFIG_HAVE_CPUMASK_OF_CPU_MAP
+#endif
+};
+
+const cpumask_t *cpumask_of_cpu_map = cpumask_map;
+
+EXPORT_SYMBOL_GPL(cpumask_of_cpu_map);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff