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Diffstat (limited to 'kernel/cpu.c')
-rw-r--r--kernel/cpu.c75
1 files changed, 34 insertions, 41 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 70fbf2e8376..f230f9ae01c 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -16,56 +16,48 @@
#include <linux/mutex.h>
/* This protects CPUs going up and down... */
-static DEFINE_MUTEX(cpucontrol);
+static DEFINE_MUTEX(cpu_add_remove_lock);
+static DEFINE_MUTEX(cpu_bitmask_lock);
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 (lock_cpu_hotplug_owner != current) {
- if (interruptible)
- ret = mutex_lock_interruptible(&cpucontrol);
- else
- mutex_lock(&cpucontrol);
- }
-
- /*
- * 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;
- mutex_unlock(&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? */
@@ -122,9 +114,7 @@ int cpu_down(unsigned int cpu)
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;
@@ -150,7 +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,
@@ -187,7 +180,7 @@ out_thread:
out_allowed:
set_cpus_allowed(current, old_allowed);
out:
- unlock_cpu_hotplug();
+ mutex_unlock(&cpu_add_remove_lock);
return err;
}
#endif /*CONFIG_HOTPLUG_CPU*/
@@ -197,9 +190,7 @@ int __devinit cpu_up(unsigned int cpu)
int ret;
void *hcpu = (void *)(long)cpu;
- if ((ret = lock_cpu_hotplug_interruptible()) != 0)
- return ret;
-
+ mutex_lock(&cpu_add_remove_lock);
if (cpu_online(cpu) || !cpu_present(cpu)) {
ret = -EINVAL;
goto out;
@@ -214,7 +205,9 @@ 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));
@@ -227,6 +220,6 @@ out_notify:
blocking_notifier_call_chain(&cpu_chain,
CPU_UP_CANCELED, hcpu);
out:
- unlock_cpu_hotplug();
+ mutex_unlock(&cpu_add_remove_lock);
return ret;
}