diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/eventpoll.h | 35 |
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 |