Commit 71def423 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Thomas Gleixner
Browse files

cpu/hotplug: Provide cpuhp_setup/remove_state[_nocalls]_cpuslocked() 



Some call sites of cpuhp_setup/remove_state[_nocalls]() are within a
cpus_read locked region.

cpuhp_setup/remove_state[_nocalls]() call cpus_read_lock() as well, which
is possible in the current implementation but prevents converting the
hotplug locking to a percpu rwsem.

Provide locked versions of the interfaces to avoid nested calls to
cpus_read_lock().

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081547.239600868@linutronix.de
parent ade3f680

include/linux/cpuhotplug.h

+29 −0
Original line number Diff line number Diff line
@@ -153,6 +153,11 @@ int __cpuhp_setup_state(enum cpuhp_state state, const char *name, bool invoke, 
			int (*startup)(unsigned int cpu),

			int (*teardown)(unsigned int cpu), bool multi_instance);



int __cpuhp_setup_state_cpuslocked(enum cpuhp_state state, const char *name,

				   bool invoke,

				   int (*startup)(unsigned int cpu),

				   int (*teardown)(unsigned int cpu),

				   bool multi_instance);

/**

 * cpuhp_setup_state - Setup hotplug state callbacks with calling the callbacks

 * @state:	The state for which the calls are installed
@@ -171,6 +176,15 @@ static inline int cpuhp_setup_state(enum cpuhp_state state, 
	return __cpuhp_setup_state(state, name, true, startup, teardown, false);

}



static inline int cpuhp_setup_state_cpuslocked(enum cpuhp_state state,

					       const char *name,

					       int (*startup)(unsigned int cpu),

					       int (*teardown)(unsigned int cpu))

{

	return __cpuhp_setup_state_cpuslocked(state, name, true, startup,

					      teardown, false);

}



/**

 * cpuhp_setup_state_nocalls - Setup hotplug state callbacks without calling the

 *			       callbacks
@@ -191,6 +205,15 @@ static inline int cpuhp_setup_state_nocalls(enum cpuhp_state state, 
				   false);

}



static inline int cpuhp_setup_state_nocalls_cpuslocked(enum cpuhp_state state,

						     const char *name,

						     int (*startup)(unsigned int cpu),

						     int (*teardown)(unsigned int cpu))

{

	return __cpuhp_setup_state_cpuslocked(state, name, false, startup,

					    teardown, false);

}



/**

 * cpuhp_setup_state_multi - Add callbacks for multi state

 * @state:	The state for which the calls are installed
@@ -250,6 +273,7 @@ static inline int cpuhp_state_add_instance_nocalls(enum cpuhp_state state, 
}



void __cpuhp_remove_state(enum cpuhp_state state, bool invoke);

void __cpuhp_remove_state_cpuslocked(enum cpuhp_state state, bool invoke);



/**

 * cpuhp_remove_state - Remove hotplug state callbacks and invoke the teardown
@@ -273,6 +297,11 @@ static inline void cpuhp_remove_state_nocalls(enum cpuhp_state state) 
	__cpuhp_remove_state(state, false);

}



static inline void cpuhp_remove_state_nocalls_cpuslocked(enum cpuhp_state state)

{

	__cpuhp_remove_state_cpuslocked(state, false);

}



/**

 * cpuhp_remove_multi_state - Remove hotplug multi state callback

 * @state:	The state for which the calls are removed

kernel/cpu.c

+36 −11
Original line number Diff line number Diff line
@@ -1459,7 +1459,7 @@ unlock: 
EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance);



/**

 * __cpuhp_setup_state - Setup the callbacks for an hotplug machine state

 * __cpuhp_setup_state_cpuslocked - Setup the callbacks for an hotplug machine state

 * @state:		The state to setup

 * @invoke:		If true, the startup function is invoked for cpus where

 *			cpu state >= @state
@@ -1468,13 +1468,14 @@ EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance); 
 * @multi_instance:	State is set up for multiple instances which get

 *			added afterwards.

 *

 * The caller needs to hold cpus read locked while calling this function.

 * Returns:

 *   On success:

 *      Positive state number if @state is CPUHP_AP_ONLINE_DYN

 *      0 for all other states

 *   On failure: proper (negative) error code

 */

int __cpuhp_setup_state(enum cpuhp_state state,

int __cpuhp_setup_state_cpuslocked(enum cpuhp_state state,

				   const char *name, bool invoke,

				   int (*startup)(unsigned int cpu),

				   int (*teardown)(unsigned int cpu),
@@ -1483,10 +1484,11 @@ int __cpuhp_setup_state(enum cpuhp_state state, 
	int cpu, ret = 0;

	bool dynstate;



	lockdep_assert_cpus_held();



	if (cpuhp_cb_check(state) || !name)

		return -EINVAL;



	cpus_read_lock();

	mutex_lock(&cpuhp_state_mutex);



	ret = cpuhp_store_callbacks(state, name, startup, teardown,
@@ -1522,7 +1524,6 @@ int __cpuhp_setup_state(enum cpuhp_state state, 
	}

out:

	mutex_unlock(&cpuhp_state_mutex);

	cpus_read_unlock();

	/*

	 * If the requested state is CPUHP_AP_ONLINE_DYN, return the

	 * dynamically allocated state in case of success.
@@ -1531,6 +1532,22 @@ out: 
		return state;

	return ret;

}

EXPORT_SYMBOL(__cpuhp_setup_state_cpuslocked);



int __cpuhp_setup_state(enum cpuhp_state state,

			const char *name, bool invoke,

			int (*startup)(unsigned int cpu),

			int (*teardown)(unsigned int cpu),

			bool multi_instance)

{

	int ret;



	cpus_read_lock();

	ret = __cpuhp_setup_state_cpuslocked(state, name, invoke, startup,

					     teardown, multi_instance);

	cpus_read_unlock();

	return ret;

}

EXPORT_SYMBOL(__cpuhp_setup_state);



int __cpuhp_state_remove_instance(enum cpuhp_state state,
@@ -1572,22 +1589,23 @@ remove: 
EXPORT_SYMBOL_GPL(__cpuhp_state_remove_instance);



/**

 * __cpuhp_remove_state - Remove the callbacks for an hotplug machine state

 * __cpuhp_remove_state_cpuslocked - Remove the callbacks for an hotplug machine state

 * @state:	The state to remove

 * @invoke:	If true, the teardown function is invoked for cpus where

 *		cpu state >= @state

 *

 * The caller needs to hold cpus read locked while calling this function.

 * The teardown callback is currently not allowed to fail. Think

 * about module removal!

 */

void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)

void __cpuhp_remove_state_cpuslocked(enum cpuhp_state state, bool invoke)

{

	struct cpuhp_step *sp = cpuhp_get_step(state);

	int cpu;



	BUG_ON(cpuhp_cb_check(state));



	cpus_read_lock();

	lockdep_assert_cpus_held();



	mutex_lock(&cpuhp_state_mutex);

	if (sp->multi_instance) {
@@ -1615,6 +1633,13 @@ void __cpuhp_remove_state(enum cpuhp_state state, bool invoke) 
remove:

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

	mutex_unlock(&cpuhp_state_mutex);

}

EXPORT_SYMBOL(__cpuhp_remove_state_cpuslocked);



void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)

{

	cpus_read_lock();

	__cpuhp_remove_state_cpuslocked(state, invoke);

	cpus_read_unlock();

}

EXPORT_SYMBOL(__cpuhp_remove_state);

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