X-Git-Url: http://git.rot13.org/?a=blobdiff_plain;f=kernel%2Fcpu.c;h=fe2b8d0bfe4ce3c76403b623b74307661a1a151f;hb=428622986858aebddc32d022af65e88b9d2ea8bb;hp=d61ba88f34e57b90edae90342ed1db59ebfbb59c;hpb=cb8a55e4cda017ed37a3ee051365f33a86956312;p=powerpc.git

diff --git a/kernel/cpu.c b/kernel/cpu.c
index d61ba88f34..fe2b8d0bfe 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -16,47 +16,68 @@
 #include <asm/semaphore.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 DECLARE_MUTEX(cpucontrol);
+
+static 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 = 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;
+}
 
-int current_in_cpu_hotplug(void)
+void lock_cpu_hotplug(void)
 {
-	return (current->flags & PF_HOTPLUG_CPU);
+	__lock_cpu_hotplug(0);
 }
+EXPORT_SYMBOL_GPL(lock_cpu_hotplug);
 
-EXPORT_SYMBOL_GPL(current_in_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)
-		return ret;
-	ret = notifier_chain_register(&cpu_chain, nb);
-	up(&cpucontrol);
-	return ret;
+	return blocking_notifier_chain_register(&cpu_chain, nb);
 }
 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);
 
@@ -112,14 +133,7 @@ int cpu_down(unsigned int cpu)
 		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",
@@ -137,7 +151,7 @@ int cpu_down(unsigned int cpu)
 	p = __stop_machine_run(take_cpu_down, NULL, cpu);
 	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();
 
@@ -160,8 +174,8 @@ int cpu_down(unsigned int cpu)
 	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);
@@ -171,7 +185,6 @@ out_thread:
 out_allowed:
 	set_cpus_allowed(current, old_allowed);
 out:
-	current->flags &= ~PF_HOTPLUG_CPU;
 	unlock_cpu_hotplug();
 	return err;
 }
@@ -182,7 +195,7 @@ 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)) {
@@ -190,12 +203,7 @@ int __devinit cpu_up(unsigned int cpu)
 		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);
@@ -207,17 +215,16 @@ int __devinit cpu_up(unsigned int cpu)
 	ret = __cpu_up(cpu);
 	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);
+	unlock_cpu_hotplug();
 	return ret;
 }