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Commit 3e51f893 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull CPU hotplug fix from Thomas Gleixner:
 "A single fix preventing the concurrent execution of the CPU hotplug
  callback install/invocation machinery. Long standing bug caused by a
  massive brain slip of that Gleixner dude, which went unnoticed for
  almost a year"

* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  cpu/hotplug: Serialize callback invocations proper
parents 8d940990 dc434e05

kernel/cpu.c

+14 −14
Original line number Diff line number Diff line
@@ -1335,26 +1335,21 @@ static int cpuhp_store_callbacks(enum cpuhp_state state, const char *name, 
	struct cpuhp_step *sp;

	int ret = 0;



	mutex_lock(&cpuhp_state_mutex);



	if (state == CPUHP_AP_ONLINE_DYN || state == CPUHP_BP_PREPARE_DYN) {

		ret = cpuhp_reserve_state(state);

		if (ret < 0)

			goto out;

			return ret;

		state = ret;

	}

	sp = cpuhp_get_step(state);

	if (name && sp->name) {

		ret = -EBUSY;

		goto out;

	}

	if (name && sp->name)

		return -EBUSY;



	sp->startup.single = startup;

	sp->teardown.single = teardown;

	sp->name = name;

	sp->multi_instance = multi_instance;

	INIT_HLIST_HEAD(&sp->list);

out:

	mutex_unlock(&cpuhp_state_mutex);

	return ret;

}
@@ -1428,6 +1423,7 @@ int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node, 
		return -EINVAL;



	get_online_cpus();

	mutex_lock(&cpuhp_state_mutex);



	if (!invoke || !sp->startup.multi)

		goto add_node;
@@ -1447,16 +1443,14 @@ int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node, 
		if (ret) {

			if (sp->teardown.multi)

				cpuhp_rollback_install(cpu, state, node);

			goto err;

			goto unlock;

		}

	}

add_node:

	ret = 0;

	mutex_lock(&cpuhp_state_mutex);

	hlist_add_head(node, &sp->list);

unlock:

	mutex_unlock(&cpuhp_state_mutex);



err:

	put_online_cpus();

	return ret;

}
@@ -1491,6 +1485,7 @@ int __cpuhp_setup_state(enum cpuhp_state state, 
		return -EINVAL;



	get_online_cpus();

	mutex_lock(&cpuhp_state_mutex);



	ret = cpuhp_store_callbacks(state, name, startup, teardown,

				    multi_instance);
@@ -1524,6 +1519,7 @@ int __cpuhp_setup_state(enum cpuhp_state state, 
		}

	}

out:

	mutex_unlock(&cpuhp_state_mutex);

	put_online_cpus();

	/*

	 * If the requested state is CPUHP_AP_ONLINE_DYN, return the
@@ -1547,6 +1543,8 @@ int __cpuhp_state_remove_instance(enum cpuhp_state state, 
		return -EINVAL;



	get_online_cpus();

	mutex_lock(&cpuhp_state_mutex);



	if (!invoke || !cpuhp_get_teardown_cb(state))

		goto remove;

	/*
@@ -1563,7 +1561,6 @@ int __cpuhp_state_remove_instance(enum cpuhp_state state, 
	}



remove:

	mutex_lock(&cpuhp_state_mutex);

	hlist_del(node);

	mutex_unlock(&cpuhp_state_mutex);

	put_online_cpus();
@@ -1571,6 +1568,7 @@ int __cpuhp_state_remove_instance(enum cpuhp_state state, 
	return 0;

}

EXPORT_SYMBOL_GPL(__cpuhp_state_remove_instance);



/**

 * __cpuhp_remove_state - Remove the callbacks for an hotplug machine state

 * @state:	The state to remove
@@ -1589,6 +1587,7 @@ void __cpuhp_remove_state(enum cpuhp_state state, bool invoke) 


	get_online_cpus();



	mutex_lock(&cpuhp_state_mutex);

	if (sp->multi_instance) {

		WARN(!hlist_empty(&sp->list),

		     "Error: Removing state %d which has instances left.\n",
@@ -1613,6 +1612,7 @@ void __cpuhp_remove_state(enum cpuhp_state state, bool invoke) 
	}

remove:

	cpuhp_store_callbacks(state, NULL, NULL, NULL, false);

	mutex_unlock(&cpuhp_state_mutex);

	put_online_cpus();

}

EXPORT_SYMBOL(__cpuhp_remove_state);