[PATCH] epoll: microoptimisations

From: Davide Libenzi <davidel@xmailserver.org>

- Inline eventpoll_release() so that __fput() does not need to call in
  epoll code if the file itself is not registered inside an epoll fd

- Add <linux/types.h> inclusion due __u32 and __u64 usage

- Fix debug printf that would otherwise panic if enabled with the new
  epoll code

1 files changed, 33 insertions, 2 deletions

diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h
index 60f8cadb1f50..f89acbe8183a 100644
--- a/include/linux/eventpoll.h
+++ b/include/linux/eventpoll.h
@@ -14,6 +14,8 @@
 #ifndef _LINUX_EVENTPOLL_H
 #define _LINUX_EVENTPOLL_H
 
+#include <linux/types.h>
+
 
 /* Valid opcodes to issue to sys_epoll_ctl() */
 #define EPOLL_CTL_ADD 1
@@ -55,8 +57,37 @@ asmlinkage long sys_epoll_wait(int epfd, struct epoll_event *events, int maxeven
 /* Used to initialize the epoll bits inside the "struct file" */
 void eventpoll_init_file(struct file *file);
 
-/* Used in fs/file_table.c:__fput() to unlink files from the eventpoll interface */
-void eventpoll_release(struct file *file);
+/* Used to release the epoll bits inside the "struct file" */
+void eventpoll_release_file(struct file *file);
+
+/*
+ * This is called from inside fs/file_table.c:__fput() to unlink files
+ * from the eventpoll interface. We need to have this facility to cleanup
+ * correctly files that are closed without being removed from the eventpoll
+ * interface.
+ */
+static inline void eventpoll_release(struct file *file)
+{
+
+	/*
+	 * Fast check to avoid the get/release of the semaphore. Since
+	 * we're doing this outside the semaphore lock, it might return
+	 * false negatives, but we don't care. It'll help in 99.99% of cases
+	 * to avoid the semaphore lock. False positives simply cannot happen
+	 * because the file in on the way to be removed and nobody ( but
+	 * eventpoll ) has still a reference to this file.
+	 */
+	if (likely(list_empty(&file->f_ep_links)))
+		return;
+
+	/*
+	 * The file is being closed while it is still linked to an epoll
+	 * descriptor. We need to handle this by correctly unlinking it
+	 * from its containers.
+	 */
+	eventpoll_release_file(file);
+}
+
 
 #else