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-rw-r--r--include/linux/percpu-refcount.h19
1 files changed, 19 insertions, 0 deletions
diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h
index 0ddd2839ca84..3dfbf237cd8f 100644
--- a/include/linux/percpu-refcount.h
+++ b/include/linux/percpu-refcount.h
@@ -67,6 +67,7 @@ struct percpu_ref {
int __must_check percpu_ref_init(struct percpu_ref *ref,
percpu_ref_func_t *release);
+void percpu_ref_reinit(struct percpu_ref *ref);
void percpu_ref_exit(struct percpu_ref *ref);
void percpu_ref_kill_and_confirm(struct percpu_ref *ref,
percpu_ref_func_t *confirm_kill);
@@ -99,6 +100,9 @@ static inline bool __pcpu_ref_alive(struct percpu_ref *ref,
{
unsigned long pcpu_ptr = ACCESS_ONCE(ref->pcpu_count_ptr);
+ /* paired with smp_store_release() in percpu_ref_reinit() */
+ smp_read_barrier_depends();
+
if (unlikely(pcpu_ptr & PCPU_REF_DEAD))
return false;
@@ -206,4 +210,19 @@ static inline void percpu_ref_put(struct percpu_ref *ref)
rcu_read_unlock_sched();
}
+/**
+ * percpu_ref_is_zero - test whether a percpu refcount reached zero
+ * @ref: percpu_ref to test
+ *
+ * Returns %true if @ref reached zero.
+ */
+static inline bool percpu_ref_is_zero(struct percpu_ref *ref)
+{
+ unsigned __percpu *pcpu_count;
+
+ if (__pcpu_ref_alive(ref, &pcpu_count))
+ return false;
+ return !atomic_read(&ref->count);
+}
+
#endif