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-rw-r--r--lib/percpu-refcount.c28
1 files changed, 26 insertions, 2 deletions
diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c
index 9f96fa7bc000..de10b8c0bff6 100644
--- 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);