#include <linux/smpboot.h>
#include <linux/relay.h>
#include <linux/slab.h>
+#include <linux/percpu-rwsem.h>
#include <trace/events/power.h>
#define CREATE_TRACE_POINTS
static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state);
+#if defined(CONFIG_LOCKDEP) && defined(CONFIG_SMP)
+static struct lock_class_key cpuhp_state_key;
+static struct lockdep_map cpuhp_state_lock_map =
+ STATIC_LOCKDEP_MAP_INIT("cpuhp_state", &cpuhp_state_key);
+#endif
+
/**
* cpuhp_step - Hotplug state machine step
* @name: Name of the step
mutex_unlock(&cpu_add_remove_lock);
}
-/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
+/*
+ * If set, cpu_up and cpu_down will return -EBUSY and do nothing.
* Should always be manipulated under cpu_add_remove_lock
*/
static int cpu_hotplug_disabled;
#ifdef CONFIG_HOTPLUG_CPU
-static struct {
- struct task_struct *active_writer;
- /* wait queue to wake up the active_writer */
- wait_queue_head_t wq;
- /* verifies that no writer will get active while readers are active */
- struct mutex lock;
- /*
- * Also blocks the new readers during
- * an ongoing cpu hotplug operation.
- */
- atomic_t refcount;
-
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
- struct lockdep_map dep_map;
-#endif
-} cpu_hotplug = {
- .active_writer = NULL,
- .wq = __WAIT_QUEUE_HEAD_INITIALIZER(cpu_hotplug.wq),
- .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
- .dep_map = STATIC_LOCKDEP_MAP_INIT("cpu_hotplug.dep_map", &cpu_hotplug.dep_map),
-#endif
-};
+DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock);
-/* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */
-#define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map)
-#define cpuhp_lock_acquire_tryread() \
- lock_map_acquire_tryread(&cpu_hotplug.dep_map)
-#define cpuhp_lock_acquire() lock_map_acquire(&cpu_hotplug.dep_map)
-#define cpuhp_lock_release() lock_map_release(&cpu_hotplug.dep_map)
-
-
-void get_online_cpus(void)
+void cpus_read_lock(void)
{
- might_sleep();
- if (cpu_hotplug.active_writer == current)
- return;
- cpuhp_lock_acquire_read();
- mutex_lock(&cpu_hotplug.lock);
- atomic_inc(&cpu_hotplug.refcount);
- mutex_unlock(&cpu_hotplug.lock);
+ percpu_down_read(&cpu_hotplug_lock);
}
-EXPORT_SYMBOL_GPL(get_online_cpus);
+EXPORT_SYMBOL_GPL(cpus_read_lock);
-void put_online_cpus(void)
+void cpus_read_unlock(void)
{
- int refcount;
-
- if (cpu_hotplug.active_writer == current)
- return;
-
- refcount = atomic_dec_return(&cpu_hotplug.refcount);
- if (WARN_ON(refcount < 0)) /* try to fix things up */
- atomic_inc(&cpu_hotplug.refcount);
-
- if (refcount <= 0 && waitqueue_active(&cpu_hotplug.wq))
- wake_up(&cpu_hotplug.wq);
-
- cpuhp_lock_release();
-
+ percpu_up_read(&cpu_hotplug_lock);
}
-EXPORT_SYMBOL_GPL(put_online_cpus);
+EXPORT_SYMBOL_GPL(cpus_read_unlock);
-/*
- * This ensures that the hotplug operation can begin only when the
- * refcount goes to zero.
- *
- * Note that during a cpu-hotplug operation, the new readers, if any,
- * will be blocked by the cpu_hotplug.lock
- *
- * Since cpu_hotplug_begin() is always called after invoking
- * cpu_maps_update_begin(), we can be sure that only one writer is active.
- *
- * Note that theoretically, there is a possibility of a livelock:
- * - Refcount goes to zero, last reader wakes up the sleeping
- * writer.
- * - Last reader unlocks the cpu_hotplug.lock.
- * - A new reader arrives at this moment, bumps up the refcount.
- * - The writer acquires the cpu_hotplug.lock finds the refcount
- * non zero and goes to sleep again.
- *
- * However, this is very difficult to achieve in practice since
- * get_online_cpus() not an api which is called all that often.
- *
- */
-void cpu_hotplug_begin(void)
+void cpus_write_lock(void)
{
- DEFINE_WAIT(wait);
-
- cpu_hotplug.active_writer = current;
- cpuhp_lock_acquire();
+ percpu_down_write(&cpu_hotplug_lock);
+}
- for (;;) {
- mutex_lock(&cpu_hotplug.lock);
- prepare_to_wait(&cpu_hotplug.wq, &wait, TASK_UNINTERRUPTIBLE);
- if (likely(!atomic_read(&cpu_hotplug.refcount)))
- break;
- mutex_unlock(&cpu_hotplug.lock);
- schedule();
- }
- finish_wait(&cpu_hotplug.wq, &wait);
+void cpus_write_unlock(void)
+{
+ percpu_up_write(&cpu_hotplug_lock);
}
-void cpu_hotplug_done(void)
+void lockdep_assert_cpus_held(void)
{
- cpu_hotplug.active_writer = NULL;
- mutex_unlock(&cpu_hotplug.lock);
- cpuhp_lock_release();
+ percpu_rwsem_assert_held(&cpu_hotplug_lock);
}
/*
EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
#endif /* CONFIG_HOTPLUG_CPU */
-/* Notifier wrappers for transitioning to state machine */
+static void __cpuhp_kick_ap_work(struct cpuhp_cpu_state *st);
static int bringup_wait_for_ap(unsigned int cpu)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ /* Wait for the CPU to reach CPUHP_AP_ONLINE_IDLE */
wait_for_completion(&st->done);
+ if (WARN_ON_ONCE((!cpu_online(cpu))))
+ return -ECANCELED;
+
+ /* Unpark the stopper thread and the hotplug thread of the target cpu */
+ stop_machine_unpark(cpu);
+ kthread_unpark(st->thread);
+
+ /* Should we go further up ? */
+ if (st->target > CPUHP_AP_ONLINE_IDLE) {
+ __cpuhp_kick_ap_work(st);
+ wait_for_completion(&st->done);
+ }
return st->result;
}
irq_unlock_sparse();
if (ret)
return ret;
- ret = bringup_wait_for_ap(cpu);
- BUG_ON(!cpu_online(cpu));
- return ret;
+ return bringup_wait_for_ap(cpu);
}
/*
st->should_run = false;
+ lock_map_acquire(&cpuhp_state_lock_map);
/* Single callback invocation for [un]install ? */
if (st->single) {
if (st->cb_state < CPUHP_AP_ONLINE) {
else if (st->state > st->target)
ret = cpuhp_ap_offline(cpu, st);
}
+ lock_map_release(&cpuhp_state_lock_map);
st->result = ret;
complete(&st->done);
}
if (!cpu_online(cpu))
return 0;
+ lock_map_acquire(&cpuhp_state_lock_map);
+ lock_map_release(&cpuhp_state_lock_map);
+
/*
* If we are up and running, use the hotplug thread. For early calls
* we invoke the thread function directly.
enum cpuhp_state state = st->state;
trace_cpuhp_enter(cpu, st->target, state, cpuhp_kick_ap_work);
+ lock_map_acquire(&cpuhp_state_lock_map);
+ lock_map_release(&cpuhp_state_lock_map);
__cpuhp_kick_ap_work(st);
wait_for_completion(&st->done);
trace_cpuhp_exit(cpu, st->state, state, st->result);
rcu_read_unlock();
}
-static inline void check_for_tasks(int dead_cpu)
-{
- struct task_struct *g, *p;
-
- read_lock(&tasklist_lock);
- for_each_process_thread(g, p) {
- if (!p->on_rq)
- continue;
- /*
- * We do the check with unlocked task_rq(p)->lock.
- * Order the reading to do not warn about a task,
- * which was running on this cpu in the past, and
- * it's just been woken on another cpu.
- */
- rmb();
- if (task_cpu(p) != dead_cpu)
- continue;
-
- pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n",
- p->comm, task_pid_nr(p), dead_cpu, p->state, p->flags);
- }
- read_unlock(&tasklist_lock);
-}
-
/* Take this CPU down. */
static int take_cpu_down(void *_param)
{
/*
* So now all preempt/rcu users must observe !cpu_active().
*/
- err = stop_machine(take_cpu_down, NULL, cpumask_of(cpu));
+ err = stop_machine_cpuslocked(take_cpu_down, NULL, cpumask_of(cpu));
if (err) {
/* CPU refused to die */
irq_unlock_sparse();
if (!cpu_present(cpu))
return -EINVAL;
- cpu_hotplug_begin();
+ cpus_write_lock();
cpuhp_tasks_frozen = tasks_frozen;
}
out:
- cpu_hotplug_done();
+ cpus_write_unlock();
return ret;
}
}
/*
- * Called from the idle task. We need to set active here, so we can kick off
- * the stopper thread and unpark the smpboot threads. If the target state is
- * beyond CPUHP_AP_ONLINE_IDLE we kick cpuhp thread and let it bring up the
- * cpu further.
+ * Called from the idle task. Wake up the controlling task which brings the
+ * stopper and the hotplug thread of the upcoming CPU up and then delegates
+ * the rest of the online bringup to the hotplug thread.
*/
void cpuhp_online_idle(enum cpuhp_state state)
{
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
- unsigned int cpu = smp_processor_id();
/* Happens for the boot cpu */
if (state != CPUHP_AP_ONLINE_IDLE)
return;
st->state = CPUHP_AP_ONLINE_IDLE;
-
- /* Unpark the stopper thread and the hotplug thread of this cpu */
- stop_machine_unpark(cpu);
- kthread_unpark(st->thread);
-
- /* Should we go further up ? */
- if (st->target > CPUHP_AP_ONLINE_IDLE)
- __cpuhp_kick_ap_work(st);
- else
- complete(&st->done);
+ complete(&st->done);
}
/* Requires cpu_add_remove_lock to be held */
struct task_struct *idle;
int ret = 0;
- cpu_hotplug_begin();
+ cpus_write_lock();
if (!cpu_present(cpu)) {
ret = -EINVAL;
target = min((int)target, CPUHP_BRINGUP_CPU);
ret = cpuhp_up_callbacks(cpu, st, target);
out:
- cpu_hotplug_done();
+ cpus_write_unlock();
return ret;
}
.startup.single = smpboot_unpark_threads,
.teardown.single = NULL,
},
+ [CPUHP_AP_IRQ_AFFINITY_ONLINE] = {
+ .name = "irq/affinity:online",
+ .startup.single = irq_affinity_online_cpu,
+ .teardown.single = NULL,
+ },
[CPUHP_AP_PERF_ONLINE] = {
.name = "perf:online",
.startup.single = perf_event_init_cpu,
}
}
-int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
- bool invoke)
+int __cpuhp_state_add_instance_cpuslocked(enum cpuhp_state state,
+ struct hlist_node *node,
+ bool invoke)
{
struct cpuhp_step *sp;
int cpu;
int ret;
+ lockdep_assert_cpus_held();
+
sp = cpuhp_get_step(state);
if (sp->multi_instance == false)
return -EINVAL;
- get_online_cpus();
mutex_lock(&cpuhp_state_mutex);
if (!invoke || !sp->startup.multi)
hlist_add_head(node, &sp->list);
unlock:
mutex_unlock(&cpuhp_state_mutex);
- put_online_cpus();
+ return ret;
+}
+
+int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
+ bool invoke)
+{
+ int ret;
+
+ cpus_read_lock();
+ ret = __cpuhp_state_add_instance_cpuslocked(state, node, invoke);
+ cpus_read_unlock();
return ret;
}
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
* @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;
- get_online_cpus();
mutex_lock(&cpuhp_state_mutex);
ret = cpuhp_store_callbacks(state, name, startup, teardown,
}
out:
mutex_unlock(&cpuhp_state_mutex);
- put_online_cpus();
/*
* If the requested state is CPUHP_AP_ONLINE_DYN, return the
* dynamically allocated state in case of success.
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,
if (!sp->multi_instance)
return -EINVAL;
- get_online_cpus();
+ cpus_read_lock();
mutex_lock(&cpuhp_state_mutex);
if (!invoke || !cpuhp_get_teardown_cb(state))
remove:
hlist_del(node);
mutex_unlock(&cpuhp_state_mutex);
- put_online_cpus();
+ cpus_read_unlock();
return 0;
}
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));
- get_online_cpus();
+ lockdep_assert_cpus_held();
mutex_lock(&cpuhp_state_mutex);
if (sp->multi_instance) {
remove:
cpuhp_store_callbacks(state, NULL, NULL, NULL, false);
mutex_unlock(&cpuhp_state_mutex);
- put_online_cpus();
+}
+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);
NULL
};
-static struct attribute_group cpuhp_cpu_attr_group = {
+static const struct attribute_group cpuhp_cpu_attr_group = {
.attrs = cpuhp_cpu_attrs,
.name = "hotplug",
NULL
NULL
};
-static struct attribute_group cpuhp_cpu_root_attr_group = {
+static const struct attribute_group cpuhp_cpu_root_attr_group = {
.attrs = cpuhp_cpu_root_attrs,
.name = "hotplug",
NULL
projects / karo-tx-linux.git / blobdiff