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-rw-r--r--kernel/cpu.c219
1 files changed, 156 insertions, 63 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index fe2b8d0bfe4..32c96628463 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -13,66 +13,66 @@
#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... */
-static DECLARE_MUTEX(cpucontrol);
+static DEFINE_MUTEX(cpu_add_remove_lock);
+static DEFINE_MUTEX(cpu_bitmask_lock);
-static BLOCKING_NOTIFIER_HEAD(cpu_chain);
+static __cpuinitdata BLOCKING_NOTIFIER_HEAD(cpu_chain);
-#ifdef CONFIG_HOTPLUG_CPU
-static struct task_struct *lock_cpu_hotplug_owner;
-static int lock_cpu_hotplug_depth;
-
-static int __lock_cpu_hotplug(int interruptible)
-{
- int ret = 0;
+/* 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;
- if (lock_cpu_hotplug_owner != current) {
- if (interruptible)
- ret = down_interruptible(&cpucontrol);
- else
- down(&cpucontrol);
- }
+#ifdef CONFIG_HOTPLUG_CPU
- /*
- * Set only if we succeed in locking
- */
- if (!ret) {
- lock_cpu_hotplug_depth++;
- lock_cpu_hotplug_owner = current;
- }
-
- return ret;
-}
+/* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */
+static struct task_struct *recursive;
+static int recursive_depth;
void lock_cpu_hotplug(void)
{
- __lock_cpu_hotplug(0);
+ 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++;
+ return;
+ }
+ mutex_lock(&cpu_bitmask_lock);
+ recursive = tsk;
}
EXPORT_SYMBOL_GPL(lock_cpu_hotplug);
void unlock_cpu_hotplug(void)
{
- if (--lock_cpu_hotplug_depth == 0) {
- lock_cpu_hotplug_owner = NULL;
- up(&cpucontrol);
+ WARN_ON(recursive != current);
+ if (recursive_depth) {
+ recursive_depth--;
+ return;
}
+ mutex_unlock(&cpu_bitmask_lock);
+ recursive = NULL;
}
EXPORT_SYMBOL_GPL(unlock_cpu_hotplug);
-int lock_cpu_hotplug_interruptible(void)
-{
- return __lock_cpu_hotplug(1);
-}
-EXPORT_SYMBOL_GPL(lock_cpu_hotplug_interruptible);
#endif /* CONFIG_HOTPLUG_CPU */
/* Need to know about CPUs going up/down? */
-int register_cpu_notifier(struct notifier_block *nb)
+int __cpuinit register_cpu_notifier(struct notifier_block *nb)
{
return blocking_notifier_chain_register(&cpu_chain, nb);
}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
EXPORT_SYMBOL(register_cpu_notifier);
void unregister_cpu_notifier(struct notifier_block *nb)
@@ -81,7 +81,6 @@ void unregister_cpu_notifier(struct notifier_block *nb)
}
EXPORT_SYMBOL(unregister_cpu_notifier);
-#ifdef CONFIG_HOTPLUG_CPU
static inline void check_for_tasks(int cpu)
{
struct task_struct *p;
@@ -114,32 +113,25 @@ static int take_cpu_down(void *unused)
return 0;
}
-int cpu_down(unsigned int cpu)
+/* Requires cpu_add_remove_lock to be held */
+static int _cpu_down(unsigned int cpu)
{
int err;
struct task_struct *p;
cpumask_t old_allowed, tmp;
- 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)) {
- err = -EINVAL;
- goto out;
- }
+ if (!cpu_online(cpu))
+ return -EINVAL;
err = blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
(void *)(long)cpu);
if (err == NOTIFY_BAD) {
printk("%s: attempt to take down CPU %u failed\n",
__FUNCTION__, cpu);
- err = -EINVAL;
- goto out;
+ return -EINVAL;
}
/* Ensure that we are not runnable on dying cpu */
@@ -148,7 +140,10 @@ int cpu_down(unsigned int cpu)
cpu_clear(cpu, tmp);
set_cpus_allowed(current, tmp);
+ mutex_lock(&cpu_bitmask_lock);
p = __stop_machine_run(take_cpu_down, NULL, cpu);
+ mutex_unlock(&cpu_bitmask_lock);
+
if (IS_ERR(p)) {
/* CPU didn't die: tell everyone. Can't complain. */
if (blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
@@ -184,24 +179,32 @@ out_thread:
err = kthread_stop(p);
out_allowed:
set_cpus_allowed(current, old_allowed);
-out:
- unlock_cpu_hotplug();
+ return err;
+}
+
+int cpu_down(unsigned int cpu)
+{
+ int err = 0;
+
+ mutex_lock(&cpu_add_remove_lock);
+ if (cpu_hotplug_disabled)
+ err = -EBUSY;
+ else
+ err = _cpu_down(cpu);
+
+ mutex_unlock(&cpu_add_remove_lock);
return err;
}
#endif /*CONFIG_HOTPLUG_CPU*/
-int __devinit cpu_up(unsigned int cpu)
+/* Requires cpu_add_remove_lock to be held */
+static int __devinit _cpu_up(unsigned int cpu)
{
int ret;
void *hcpu = (void *)(long)cpu;
- if ((ret = lock_cpu_hotplug_interruptible()) != 0)
- return ret;
-
- if (cpu_online(cpu) || !cpu_present(cpu)) {
- ret = -EINVAL;
- goto out;
- }
+ if (cpu_online(cpu) || !cpu_present(cpu))
+ return -EINVAL;
ret = blocking_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);
if (ret == NOTIFY_BAD) {
@@ -212,7 +215,9 @@ int __devinit cpu_up(unsigned int cpu)
}
/* 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));
@@ -224,7 +229,95 @@ out_notify:
if (ret != 0)
blocking_notifier_call_chain(&cpu_chain,
CPU_UP_CANCELED, hcpu);
-out:
- unlock_cpu_hotplug();
+
return ret;
}
+
+int __devinit cpu_up(unsigned int cpu)
+{
+ int err = 0;
+
+ mutex_lock(&cpu_add_remove_lock);
+ if (cpu_hotplug_disabled)
+ err = -EBUSY;
+ else
+ err = _cpu_up(cpu);
+
+ mutex_unlock(&cpu_add_remove_lock);
+ return err;
+}
+
+#ifdef CONFIG_SUSPEND_SMP
+static cpumask_t frozen_cpus;
+
+int disable_nonboot_cpus(void)
+{
+ int cpu, first_cpu, error;
+
+ mutex_lock(&cpu_add_remove_lock);
+ first_cpu = first_cpu(cpu_present_map);
+ if (!cpu_online(first_cpu)) {
+ error = _cpu_up(first_cpu);
+ if (error) {
+ printk(KERN_ERR "Could not bring CPU%d up.\n",
+ first_cpu);
+ goto out;
+ }
+ }
+ error = set_cpus_allowed(current, cpumask_of_cpu(first_cpu));
+ if (error) {
+ printk(KERN_ERR "Could not run on CPU%d\n", first_cpu);
+ goto out;
+ }
+ /* 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
+ */
+ cpus_clear(frozen_cpus);
+ printk("Disabling non-boot CPUs ...\n");
+ for_each_online_cpu(cpu) {
+ if (cpu == first_cpu)
+ continue;
+ error = _cpu_down(cpu);
+ if (!error) {
+ cpu_set(cpu, frozen_cpus);
+ printk("CPU%d is down\n", cpu);
+ } 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");
+ }
+out:
+ mutex_unlock(&cpu_add_remove_lock);
+ return error;
+}
+
+void enable_nonboot_cpus(void)
+{
+ int cpu, error;
+
+ /* Allow everyone to use the CPU hotplug again */
+ mutex_lock(&cpu_add_remove_lock);
+ cpu_hotplug_disabled = 0;
+ mutex_unlock(&cpu_add_remove_lock);
+
+ printk("Enabling non-boot CPUs ...\n");
+ for_each_cpu_mask(cpu, frozen_cpus) {
+ error = cpu_up(cpu);
+ if (!error) {
+ printk("CPU%d is up\n", cpu);
+ continue;
+ }
+ printk(KERN_WARNING "Error taking CPU%d up: %d\n",
+ cpu, error);
+ }
+ cpus_clear(frozen_cpus);
+}
+#endif
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