[PATCH 06/17] eventpoll: rename ep_refcount_dec_and_test() to ep_put()

[Christian Brauner <brauner@kernel.org>]

ep_refcount_dec_and_test() mirrors refcount_dec_and_test() verbatim,
which reads fine at a call site like

  if (ep_refcount_dec_and_test(ep))
      ep_free(ep);

but awkward at

  WARN_ON_ONCE(ep_refcount_dec_and_test(ep));

and does not pair cleanly with ep_get(). Rename to the idiomatic
ep_put() and reword the kerneldoc to spell out the return-value
contract (caller is responsible for ep_free() iff the return is
true). Leave ep_put() as a bool-returning wrapper -- we cannot fold
ep_free() into it because ep_remove() calls it under ep->mtx and the
mutex would still be held when ep_free()'s mutex_destroy() ran (see
commit 8c2e52ebbe88 "eventpoll: don't decrement ep refcount while
still holding the ep mutex").

No functional change.

Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
 fs/eventpoll.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index b6a14c69c482..da31a3ac6057 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -969,9 +969,10 @@ static void ep_get(struct eventpoll *ep)
 }
 
 /*
- * Returns true if the event poll can be disposed
+ * Drop a reference to @ep; returns true iff it was the last, in which
+ * case the caller is responsible for ep_free().
  */
-static bool ep_refcount_dec_and_test(struct eventpoll *ep)
+static bool ep_put(struct eventpoll *ep)
 {
 	if (!refcount_dec_and_test(&ep->refcount))
 		return false;
@@ -1100,7 +1101,7 @@ static void ep_remove(struct eventpoll *ep, struct epitem *epi)
 
 	ep_remove_file(ep, epi, file);
 	ep_remove_epi(ep, epi);
-	WARN_ON_ONCE(ep_refcount_dec_and_test(ep));
+	WARN_ON_ONCE(ep_put(ep));
 }
 
 /*
@@ -1160,7 +1161,7 @@ static void ep_clear_and_put(struct eventpoll *ep)
 	}
 
 	mutex_unlock(&ep->mtx);
-	if (ep_refcount_dec_and_test(ep))
+	if (ep_put(ep))
 		ep_free(ep);
 }
 
@@ -1339,7 +1340,7 @@ void eventpoll_release_file(struct file *file)
 
 		mutex_unlock(&ep->mtx);
 
-		if (ep_refcount_dec_and_test(ep))
+		if (ep_put(ep))
 			ep_free(ep);
 		goto again;
 	}

-- 
2.47.3