[PATCH] Add the canary field to the PDA area and the task struct

[pandora-kernel.git] / kernel / cpu.c

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 03dcd98..f230f9a 100644 (file)
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -16,63 +16,58 @@
 #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 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 (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? */
-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 +76,6 @@ 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;
@@ -120,9 +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;
@@ -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,
@@ -185,7 +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*/
@@ -195,9 +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;
@@ -212,7 +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));
@@ -225,6 +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;
 }