#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);
-
-static struct notifier_block *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
- */
+static DEFINE_MUTEX(cpu_add_remove_lock);
+static DEFINE_MUTEX(cpu_bitmask_lock);
+
+static __cpuinitdata BLOCKING_NOTIFIER_HEAD(cpu_chain);
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+/* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */
+static struct task_struct *recursive;
+static int recursive_depth;
-int current_in_cpu_hotplug(void)
+void lock_cpu_hotplug(void)
{
- return (current->flags & PF_HOTPLUG_CPU);
+ 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);
-EXPORT_SYMBOL_GPL(current_in_cpu_hotplug);
+void unlock_cpu_hotplug(void)
+{
+ WARN_ON(recursive != current);
+ if (recursive_depth) {
+ recursive_depth--;
+ return;
+ }
+ mutex_unlock(&cpu_bitmask_lock);
+ recursive = NULL;
+}
+EXPORT_SYMBOL_GPL(unlock_cpu_hotplug);
+#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)
{
- int ret;
-
- if ((ret = down_interruptible(&cpucontrol)) != 0)
- return ret;
- ret = notifier_chain_register(&cpu_chain, nb);
- up(&cpucontrol);
- return ret;
+ 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)
{
- down(&cpucontrol);
- notifier_chain_unregister(&cpu_chain, nb);
- up(&cpucontrol);
+ blocking_notifier_chain_unregister(&cpu_chain, nb);
}
EXPORT_SYMBOL(unregister_cpu_notifier);
-#ifdef CONFIG_HOTPLUG_CPU
static inline void check_for_tasks(int cpu)
{
struct task_struct *p;
struct task_struct *p;
cpumask_t old_allowed, tmp;
- if ((err = lock_cpu_hotplug_interruptible()) != 0)
- return err;
-
+ mutex_lock(&cpu_add_remove_lock);
if (num_online_cpus() == 1) {
err = -EBUSY;
goto out;
goto out;
}
- /*
- * 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,
+ 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",
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 (notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
+ if (blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
(void *)(long)cpu) == NOTIFY_BAD)
BUG();
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 (blocking_notifier_call_chain(&cpu_chain, CPU_DEAD,
+ (void *)(long)cpu) == NOTIFY_BAD)
BUG();
check_for_tasks(cpu);
out_allowed:
set_cpus_allowed(current, old_allowed);
out:
- current->flags &= ~PF_HOTPLUG_CPU;
- unlock_cpu_hotplug();
+ mutex_unlock(&cpu_add_remove_lock);
return err;
}
#endif /*CONFIG_HOTPLUG_CPU*/
int ret;
void *hcpu = (void *)(long)cpu;
- if ((ret = down_interruptible(&cpucontrol)) != 0)
- return ret;
-
+ mutex_lock(&cpu_add_remove_lock);
if (cpu_online(cpu) || !cpu_present(cpu)) {
ret = -EINVAL;
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);
+ ret = blocking_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);
if (ret == NOTIFY_BAD) {
printk("%s: attempt to bring up CPU %u failed\n",
__FUNCTION__, 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;
- if (!cpu_online(cpu))
- BUG();
+ BUG_ON(!cpu_online(cpu));
/* Now call notifier in preparation. */
- notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
+ blocking_notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
out_notify:
if (ret != 0)
- notifier_call_chain(&cpu_chain, CPU_UP_CANCELED, hcpu);
+ blocking_notifier_call_chain(&cpu_chain,
+ CPU_UP_CANCELED, hcpu);
out:
- current->flags &= ~PF_HOTPLUG_CPU;
- up(&cpucontrol);
+ mutex_unlock(&cpu_add_remove_lock);
return ret;
}
projects / mv-sheeva.git / blobdiff