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

[Al Viro]

From: Al Viro <v...@zeniv.linux.org.uk>

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

Signed-off-by: Al Viro <v...@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