percpu-refcount: Introduce percpu_ref_resurrect()

[sfrench/cifs-2.6.git] / lib / percpu-refcount.c

diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c
index 9f96fa7bc0006e6eb38d4c88aba96d8ea04049fb..de10b8c0bff683399baa2a28c2b57f50445ab3da 100644 (file)
--- a/lib/percpu-refcount.c
+++ b/lib/percpu-refcount.c
@@ -356,11 +356,35 @@ EXPORT_SYMBOL_GPL(percpu_ref_kill_and_confirm);
  */
 void percpu_ref_reinit(struct percpu_ref *ref)
 {
+       WARN_ON_ONCE(!percpu_ref_is_zero(ref));
+
+       percpu_ref_resurrect(ref);
+}
+EXPORT_SYMBOL_GPL(percpu_ref_reinit);
+
+/**
+ * percpu_ref_resurrect - modify a percpu refcount from dead to live
+ * @ref: perpcu_ref to resurrect
+ *
+ * Modify @ref so that it's in the same state as before percpu_ref_kill() was
+ * called. @ref must be dead but must not yet have exited.
+ *
+ * If @ref->release() frees @ref then the caller is responsible for
+ * guaranteeing that @ref->release() does not get called while this
+ * function is in progress.
+ *
+ * Note that percpu_ref_tryget[_live]() are safe to perform on @ref while
+ * this function is in progress.
+ */
+void percpu_ref_resurrect(struct percpu_ref *ref)
+{
+       unsigned long __percpu *percpu_count;
        unsigned long flags;
 
        spin_lock_irqsave(&percpu_ref_switch_lock, flags);
 
-       WARN_ON_ONCE(!percpu_ref_is_zero(ref));
+       WARN_ON_ONCE(!(ref->percpu_count_ptr & __PERCPU_REF_DEAD));
+       WARN_ON_ONCE(__ref_is_percpu(ref, &percpu_count));
 
        ref->percpu_count_ptr &= ~__PERCPU_REF_DEAD;
        percpu_ref_get(ref);
@@ -368,4 +392,4 @@ void percpu_ref_reinit(struct percpu_ref *ref)
 
        spin_unlock_irqrestore(&percpu_ref_switch_lock, flags);
 }
-EXPORT_SYMBOL_GPL(percpu_ref_reinit);
+EXPORT_SYMBOL_GPL(percpu_ref_resurrect);