[PATCH 5/5] percpu: Kill off PERCPU_REF_INIT_DEAD and percpu_ref_reinit()

[David Howells <dhowells@xxxxxxxxxx>]

Kill off PERCPU_REF_INIT_DEAD and percpu_ref_reinit() for lack of users.

They were being used in cgroups, but this was causing problems with the
refcounting in the event that kernfs_get_tree() created a superblock and
then failed with the refcount not fully initialised.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

 include/linux/percpu-refcount.h |    7 -------
 lib/percpu-refcount.c           |   31 +++----------------------------
 2 files changed, 3 insertions(+), 35 deletions(-)

diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h
index b297cd1cd4f1..fdd69b99f331 100644
--- a/include/linux/percpu-refcount.h
+++ b/include/linux/percpu-refcount.h
@@ -77,12 +77,6 @@ enum {
 	 * percpu_ref_switch_to_percpu() is invoked on it.
 	 */
 	PERCPU_REF_INIT_ATOMIC	= 1 << 0,
-
-	/*
-	 * Start dead w/ ref == 0 in atomic mode.  Must be revived with
-	 * percpu_ref_reinit() before used.  Implies INIT_ATOMIC.
-	 */
-	PERCPU_REF_INIT_DEAD	= 1 << 1,
 };
 
 struct percpu_ref {
@@ -109,7 +103,6 @@ void percpu_ref_switch_to_percpu(struct percpu_ref *ref);
 void percpu_ref_kill_and_confirm(struct percpu_ref *ref,
 				 percpu_ref_func_t *confirm_kill);
 void percpu_ref_resurrect(struct percpu_ref *ref);
-void percpu_ref_reinit(struct percpu_ref *ref);
 
 /**
  * percpu_ref_kill - drop the initial ref
diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c
index de10b8c0bff6..7a56c36aec5d 100644
--- a/lib/percpu-refcount.c
+++ b/lib/percpu-refcount.c
@@ -70,15 +70,12 @@ int percpu_ref_init(struct percpu_ref *ref, percpu_ref_func_t *release,
 
 	ref->force_atomic = flags & PERCPU_REF_INIT_ATOMIC;
 
-	if (flags & (PERCPU_REF_INIT_ATOMIC | PERCPU_REF_INIT_DEAD))
+	if (flags & PERCPU_REF_INIT_ATOMIC)
 		ref->percpu_count_ptr |= __PERCPU_REF_ATOMIC;
 	else
 		start_count += PERCPU_COUNT_BIAS;
 
-	if (flags & PERCPU_REF_INIT_DEAD)
-		ref->percpu_count_ptr |= __PERCPU_REF_DEAD;
-	else
-		start_count++;
+	start_count++;
 
 	atomic_long_set(&ref->count, start_count);
 
@@ -282,14 +279,11 @@ EXPORT_SYMBOL_GPL(percpu_ref_switch_to_atomic_sync);
  * @ref: percpu_ref to switch to percpu mode
  *
  * There's no reason to use this function for the usual reference counting.
- * To re-use an expired ref, use percpu_ref_reinit().
  *
  * Switch @ref to percpu mode.  This function may be invoked concurrently
  * with all the get/put operations and can safely be mixed with kill and
  * reinit operations.  This function reverses the sticky atomic state set
- * by PERCPU_REF_INIT_ATOMIC or percpu_ref_switch_to_atomic().  If @ref is
- * dying or dead, the actual switching takes place on the following
- * percpu_ref_reinit().
+ * by PERCPU_REF_INIT_ATOMIC or percpu_ref_switch_to_atomic().
  *
  * This function may block if @ref is in the process of switching to atomic
  * mode.  If the caller ensures that @ref is not in the process of
@@ -343,25 +337,6 @@ void percpu_ref_kill_and_confirm(struct percpu_ref *ref,
 }
 EXPORT_SYMBOL_GPL(percpu_ref_kill_and_confirm);
 
-/**
- * percpu_ref_reinit - re-initialize a percpu refcount
- * @ref: perpcu_ref to re-initialize
- *
- * Re-initialize @ref so that it's in the same state as when it finished
- * percpu_ref_init() ignoring %PERCPU_REF_INIT_DEAD.  @ref must have been
- * initialized successfully and reached 0 but not exited.
- *
- * Note that percpu_ref_tryget[_live]() are safe to perform on @ref while
- * this function is in progress.
- */
-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