[RFC PATCH 14/27] ep_scan_ready_list(): prepare to splitup

Al Viro
2020-10-04T02:39:56Z

take the stuff done before and after the callback into separate helpers

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/eventpoll.c | 63 +++++++++++++++++++++++++++++++++-------------------------
1 file changed, 36 insertions(+), 27 deletions(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index e971e3ace557..eb012fdc152e 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -561,28 +561,10 @@ static inline void ep_pm_stay_awake_rcu(struct epitem *epi)
rcu_read_unlock();
}

-/**
- * ep_scan_ready_list - Scans the ready list in a way that makes possible for
- * the scan code, to call f_op->poll(). Also allows for
- * O(NumReady) performance.
- *
- * @ep: Pointer to the epoll private data structure.
- * @sproc: Pointer to the scan callback.
- * @priv: Private opaque data passed to the @sproc callback.
- * @depth: The current depth of recursive f_op->poll calls.
- * @ep_locked: caller already holds ep->mtx
- *
- * Returns: The same integer error code returned by the @sproc callback.
- */
-static __poll_t ep_scan_ready_list(struct eventpoll *ep,
- __poll_t (*sproc)(struct eventpoll *,
- struct list_head *, void *),
- void *priv, int depth, bool ep_locked)
+static void ep_start_scan(struct eventpoll *ep,
+ int depth, bool ep_locked,
+ struct list_head *txlist)
{
- __poll_t res;
- struct epitem *epi, *nepi;
- LIST_HEAD(txlist);
-
lockdep_assert_irqs_enabled();

/*
@@ -602,14 +584,16 @@ static __poll_t ep_scan_ready_list(struct eventpoll *ep,
* in a lockless way.
*/
write_lock_irq(&ep->lock);
- list_splice_init(&ep->rdllist, &txlist);
+ list_splice_init(&ep->rdllist, txlist);
WRITE_ONCE(ep->ovflist, NULL);
write_unlock_irq(&ep->lock);
+}

- /*
- * Now call the callback function.
- */
- res = (*sproc)(ep, &txlist, priv);
+static void ep_done_scan(struct eventpoll *ep,
+ int depth, bool ep_locked,
+ struct list_head *txlist)
+{
+ struct epitem *epi, *nepi;

write_lock_irq(&ep->lock);
/*
@@ -644,13 +628,38 @@ static __poll_t ep_scan_ready_list(struct eventpoll *ep,
/*
* Quickly re-inject items left on "txlist".
*/
- list_splice(&txlist, &ep->rdllist);
+ list_splice(txlist, &ep->rdllist);
__pm_relax(ep->ws);
write_unlock_irq(&ep->lock);

if (!ep_locked)
mutex_unlock(&ep->mtx);
+}

+/**
+ * ep_scan_ready_list - Scans the ready list in a way that makes possible for
+ * the scan code, to call f_op->poll(). Also allows for
+ * O(NumReady) performance.
+ *
+ * @ep: Pointer to the epoll private data structure.
+ * @sproc: Pointer to the scan callback.
+ * @priv: Private opaque data passed to the @sproc callback.
+ * @depth: The current depth of recursive f_op->poll calls.
+ * @ep_locked: caller already holds ep->mtx
+ *
+ * Returns: The same integer error code returned by the @sproc callback.
+ */
+static __poll_t ep_scan_ready_list(struct eventpoll *ep,
+ __poll_t (*sproc)(struct eventpoll *,
+ struct list_head *, void *),
+ void *priv, int depth, bool ep_locked)
+{
+ __poll_t res;
+ LIST_HEAD(txlist);
+
+ ep_start_scan(ep, depth, ep_locked, &txlist);
+ res = (*sproc)(ep, &txlist, priv);
+ ep_done_scan(ep, depth, ep_locked, &txlist);
return res;
}

--
2.11.0