percpu-refcount: rename percpu_ref_tryget() to percpu_ref_tryget_live()

percpu_ref_tryget() is different from the usual tryget semantics in
that it fails if the refcnt is in its dying stage even if the refcnt
hasn't reached zero yet.  We're about to introduce the more
conventional tryget and the current one has only one user.  Let's
rename it to percpu_ref_tryget_live() so that it explicitly signifies
the peculiarities of its semantics.

This is pure rename.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NKent Overstreet <kmo@daterainc.com>

include/linux/cgroup.h

@@ -101,7 +101,7 @@ static inline bool css_tryget(struct cgroup_subsys_state *css)
 {
 	if (css->flags & CSS_ROOT)
 		return true;
-	return percpu_ref_tryget(&css->refcnt);
+	return percpu_ref_tryget_live(&css->refcnt);
 }
 
 /**

include/linux/percpu-refcount.h

@@ -118,7 +118,7 @@ static inline void percpu_ref_get(struct percpu_ref *ref)
 }
 
 /**
- * percpu_ref_tryget - try to increment a percpu refcount
+ * percpu_ref_tryget_live - try to increment a live percpu refcount
  * @ref: percpu_ref to try-get
  *
  * Increment a percpu refcount unless it has already been killed.  Returns
@@ -129,7 +129,7 @@ static inline void percpu_ref_get(struct percpu_ref *ref)
  * used.  After the confirm_kill callback is invoked, it's guaranteed that
  * no new reference will be given out by percpu_ref_tryget().
  */
-static inline bool percpu_ref_tryget(struct percpu_ref *ref)
+static inline bool percpu_ref_tryget_live(struct percpu_ref *ref)
 {
 	unsigned __percpu *pcpu_count;
 	int ret = false;