#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/wait.h>
+#include <linux/slab.h>
#include <linux/percpu-refcount.h>
/*
size_t align = max_t(size_t, 1 << __PERCPU_REF_FLAG_BITS,
__alignof__(unsigned long));
unsigned long start_count = 0;
+ struct percpu_ref_data *data;
ref->percpu_count_ptr = (unsigned long)
__alloc_percpu_gfp(sizeof(unsigned long), align, gfp);
if (!ref->percpu_count_ptr)
return -ENOMEM;
- ref->force_atomic = flags & PERCPU_REF_INIT_ATOMIC;
- ref->allow_reinit = flags & PERCPU_REF_ALLOW_REINIT;
+ data = kzalloc(sizeof(*ref->data), gfp);
+ if (!data) {
+ free_percpu((void __percpu *)ref->percpu_count_ptr);
+ return -ENOMEM;
+ }
+
+ data->force_atomic = flags & PERCPU_REF_INIT_ATOMIC;
+ data->allow_reinit = flags & PERCPU_REF_ALLOW_REINIT;
if (flags & (PERCPU_REF_INIT_ATOMIC | PERCPU_REF_INIT_DEAD)) {
ref->percpu_count_ptr |= __PERCPU_REF_ATOMIC;
- ref->allow_reinit = true;
+ data->allow_reinit = true;
} else {
start_count += PERCPU_COUNT_BIAS;
}
else
start_count++;
- atomic_long_set(&ref->count, start_count);
+ atomic_long_set(&data->count, start_count);
- ref->release = release;
- ref->confirm_switch = NULL;
+ data->release = release;
+ data->confirm_switch = NULL;
+ data->ref = ref;
+ ref->data = data;
return 0;
}
EXPORT_SYMBOL_GPL(percpu_ref_init);
+static void __percpu_ref_exit(struct percpu_ref *ref)
+{
+ unsigned long __percpu *percpu_count = percpu_count_ptr(ref);
+
+ if (percpu_count) {
+ /* non-NULL confirm_switch indicates switching in progress */
+ WARN_ON_ONCE(ref->data && ref->data->confirm_switch);
+ free_percpu(percpu_count);
+ ref->percpu_count_ptr = __PERCPU_REF_ATOMIC_DEAD;
+ }
+}
+
/**
* percpu_ref_exit - undo percpu_ref_init()
* @ref: percpu_ref to exit
*/
void percpu_ref_exit(struct percpu_ref *ref)
{
- unsigned long __percpu *percpu_count = percpu_count_ptr(ref);
+ struct percpu_ref_data *data = ref->data;
+ unsigned long flags;
- if (percpu_count) {
- /* non-NULL confirm_switch indicates switching in progress */
- WARN_ON_ONCE(ref->confirm_switch);
- free_percpu(percpu_count);
- ref->percpu_count_ptr = __PERCPU_REF_ATOMIC_DEAD;
- }
+ __percpu_ref_exit(ref);
+
+ if (!data)
+ return;
+
+ spin_lock_irqsave(&percpu_ref_switch_lock, flags);
+ ref->percpu_count_ptr |= atomic_long_read(&ref->data->count) <<
+ __PERCPU_REF_FLAG_BITS;
+ ref->data = NULL;
+ spin_unlock_irqrestore(&percpu_ref_switch_lock, flags);
+
+ kfree(data);
}
EXPORT_SYMBOL_GPL(percpu_ref_exit);
static void percpu_ref_call_confirm_rcu(struct rcu_head *rcu)
{
- struct percpu_ref *ref = container_of(rcu, struct percpu_ref, rcu);
+ struct percpu_ref_data *data = container_of(rcu,
+ struct percpu_ref_data, rcu);
+ struct percpu_ref *ref = data->ref;
- ref->confirm_switch(ref);
- ref->confirm_switch = NULL;
+ data->confirm_switch(ref);
+ data->confirm_switch = NULL;
wake_up_all(&percpu_ref_switch_waitq);
- if (!ref->allow_reinit)
- percpu_ref_exit(ref);
+ if (!data->allow_reinit)
+ __percpu_ref_exit(ref);
/* drop ref from percpu_ref_switch_to_atomic() */
percpu_ref_put(ref);
static void percpu_ref_switch_to_atomic_rcu(struct rcu_head *rcu)
{
- struct percpu_ref *ref = container_of(rcu, struct percpu_ref, rcu);
+ struct percpu_ref_data *data = container_of(rcu,
+ struct percpu_ref_data, rcu);
+ struct percpu_ref *ref = data->ref;
unsigned long __percpu *percpu_count = percpu_count_ptr(ref);
unsigned long count = 0;
int cpu;
count += *per_cpu_ptr(percpu_count, cpu);
pr_debug("global %lu percpu %lu\n",
- atomic_long_read(&ref->count), count);
+ atomic_long_read(&data->count), count);
/*
* It's crucial that we sum the percpu counters _before_ adding the sum
* reaching 0 before we add the percpu counts. But doing it at the same
* time is equivalent and saves us atomic operations:
*/
- atomic_long_add((long)count - PERCPU_COUNT_BIAS, &ref->count);
+ atomic_long_add((long)count - PERCPU_COUNT_BIAS, &data->count);
- WARN_ONCE(atomic_long_read(&ref->count) <= 0,
+ WARN_ONCE(atomic_long_read(&data->count) <= 0,
"percpu ref (%ps) <= 0 (%ld) after switching to atomic",
- ref->release, atomic_long_read(&ref->count));
+ data->release, atomic_long_read(&data->count));
/* @ref is viewed as dead on all CPUs, send out switch confirmation */
percpu_ref_call_confirm_rcu(rcu);
* Non-NULL ->confirm_switch is used to indicate that switching is
* in progress. Use noop one if unspecified.
*/
- ref->confirm_switch = confirm_switch ?: percpu_ref_noop_confirm_switch;
+ ref->data->confirm_switch = confirm_switch ?:
+ percpu_ref_noop_confirm_switch;
percpu_ref_get(ref); /* put after confirmation */
- call_rcu(&ref->rcu, percpu_ref_switch_to_atomic_rcu);
+ call_rcu(&ref->data->rcu, percpu_ref_switch_to_atomic_rcu);
}
static void __percpu_ref_switch_to_percpu(struct percpu_ref *ref)
if (!(ref->percpu_count_ptr & __PERCPU_REF_ATOMIC))
return;
- if (WARN_ON_ONCE(!ref->allow_reinit))
+ if (WARN_ON_ONCE(!ref->data->allow_reinit))
return;
- atomic_long_add(PERCPU_COUNT_BIAS, &ref->count);
+ atomic_long_add(PERCPU_COUNT_BIAS, &ref->data->count);
/*
* Restore per-cpu operation. smp_store_release() is paired
static void __percpu_ref_switch_mode(struct percpu_ref *ref,
percpu_ref_func_t *confirm_switch)
{
+ struct percpu_ref_data *data = ref->data;
+
lockdep_assert_held(&percpu_ref_switch_lock);
/*
* its completion. If the caller ensures that ATOMIC switching
* isn't in progress, this function can be called from any context.
*/
- wait_event_lock_irq(percpu_ref_switch_waitq, !ref->confirm_switch,
+ wait_event_lock_irq(percpu_ref_switch_waitq, !data->confirm_switch,
percpu_ref_switch_lock);
- if (ref->force_atomic || (ref->percpu_count_ptr & __PERCPU_REF_DEAD))
+ if (data->force_atomic || (ref->percpu_count_ptr & __PERCPU_REF_DEAD))
__percpu_ref_switch_to_atomic(ref, confirm_switch);
else
__percpu_ref_switch_to_percpu(ref);
spin_lock_irqsave(&percpu_ref_switch_lock, flags);
- ref->force_atomic = true;
+ ref->data->force_atomic = true;
__percpu_ref_switch_mode(ref, confirm_switch);
spin_unlock_irqrestore(&percpu_ref_switch_lock, flags);
void percpu_ref_switch_to_atomic_sync(struct percpu_ref *ref)
{
percpu_ref_switch_to_atomic(ref, NULL);
- wait_event(percpu_ref_switch_waitq, !ref->confirm_switch);
+ wait_event(percpu_ref_switch_waitq, !ref->data->confirm_switch);
}
EXPORT_SYMBOL_GPL(percpu_ref_switch_to_atomic_sync);
spin_lock_irqsave(&percpu_ref_switch_lock, flags);
- ref->force_atomic = false;
+ ref->data->force_atomic = false;
__percpu_ref_switch_mode(ref, NULL);
spin_unlock_irqrestore(&percpu_ref_switch_lock, flags);
spin_lock_irqsave(&percpu_ref_switch_lock, flags);
WARN_ONCE(ref->percpu_count_ptr & __PERCPU_REF_DEAD,
- "%s called more than once on %ps!", __func__, ref->release);
+ "%s called more than once on %ps!", __func__,
+ ref->data->release);
ref->percpu_count_ptr |= __PERCPU_REF_DEAD;
__percpu_ref_switch_mode(ref, confirm_kill);
}
EXPORT_SYMBOL_GPL(percpu_ref_kill_and_confirm);
+/**
+ * percpu_ref_is_zero - test whether a percpu refcount reached zero
+ * @ref: percpu_ref to test
+ *
+ * Returns %true if @ref reached zero.
+ *
+ * This function is safe to call as long as @ref is between init and exit.
+ */
+bool percpu_ref_is_zero(struct percpu_ref *ref)
+{
+ unsigned long __percpu *percpu_count;
+ unsigned long count, flags;
+
+ if (__ref_is_percpu(ref, &percpu_count))
+ return false;
+
+ /* protect us from being destroyed */
+ spin_lock_irqsave(&percpu_ref_switch_lock, flags);
+ if (ref->data)
+ count = atomic_long_read(&ref->data->count);
+ else
+ count = ref->percpu_count_ptr >> __PERCPU_REF_FLAG_BITS;
+ spin_unlock_irqrestore(&percpu_ref_switch_lock, flags);
+
+ return count == 0;
+}
+EXPORT_SYMBOL_GPL(percpu_ref_is_zero);
+
/**
* percpu_ref_reinit - re-initialize a percpu refcount
* @ref: perpcu_ref to re-initialize
projects / linux-2.6-microblaze.git / blobdiff