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

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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: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Ingo 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
tirimbino
Sebastian Andrzej Siewior 8 years ago committed by Thomas Gleixner
parent ade3f680a7
commit 71def423fe
2 changed files with 65 additions and 11 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 29
      include/linux/cpuhotplug.h
  2. 47
      kernel/cpu.c

29
include/linux/cpuhotplug.h
Unescape View File

@ -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

47
kernel/cpu.c
Unescape View File

@ -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
@ -1468,25 +1468,27 @@ 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,
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)
{
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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