powerpc: Fix bug causing FP registers corruption on UP + preempt

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

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 3619e93..e882c6b 100644 (file)
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -16,29 +16,76 @@
 #include <asm/semaphore.h>
 
 /* This protects CPUs going up and down... */
-DECLARE_MUTEX(cpucontrol);
-EXPORT_SYMBOL_GPL(cpucontrol);
+static DECLARE_MUTEX(cpucontrol);
 
 static struct notifier_block *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 = down_interruptible(&cpucontrol);
+               else
+                       down(&cpucontrol);
+       }
+
+       /*
+        * Set only if we succeed in locking
+        */
+       if (!ret) {
+               lock_cpu_hotplug_depth++;
+               lock_cpu_hotplug_owner = current;
+       }
+
+       return ret;
+}
+
+void lock_cpu_hotplug(void)
+{
+       __lock_cpu_hotplug(0);
+}
+EXPORT_SYMBOL_GPL(lock_cpu_hotplug);
+
+void unlock_cpu_hotplug(void)
+{
+       if (--lock_cpu_hotplug_depth == 0) {
+               lock_cpu_hotplug_owner = NULL;
+               up(&cpucontrol);
+       }
+}
+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 ret;
 
-       if ((ret = down_interruptible(&cpucontrol)) != 0)
+       if ((ret = lock_cpu_hotplug_interruptible()) != 0)
                return ret;
        ret = notifier_chain_register(&cpu_chain, nb);
-       up(&cpucontrol);
+       unlock_cpu_hotplug();
        return ret;
 }
 EXPORT_SYMBOL(register_cpu_notifier);
 
 void unregister_cpu_notifier(struct notifier_block *nb)
 {
-       down(&cpucontrol);
+       lock_cpu_hotplug();
        notifier_chain_unregister(&cpu_chain, nb);
-       up(&cpucontrol);
+       unlock_cpu_hotplug();
 }
 EXPORT_SYMBOL(unregister_cpu_notifier);
 
@@ -156,13 +203,14 @@ int __devinit cpu_up(unsigned int cpu)
        int ret;
        void *hcpu = (void *)(long)cpu;
 
-       if ((ret = down_interruptible(&cpucontrol)) != 0)
+       if ((ret = lock_cpu_hotplug_interruptible()) != 0)
                return ret;
 
        if (cpu_online(cpu) || !cpu_present(cpu)) {
                ret = -EINVAL;
                goto out;
        }
+
        ret = notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);
        if (ret == NOTIFY_BAD) {
                printk("%s: attempt to bring up CPU %u failed\n",
@@ -185,6 +233,6 @@ out_notify:
        if (ret != 0)
                notifier_call_chain(&cpu_chain, CPU_UP_CANCELED, hcpu);
 out:
-       up(&cpucontrol);
+       unlock_cpu_hotplug();
        return ret;
 }