diff options
Diffstat (limited to 'include/linux/eventpoll.h')
| -rw-r--r-- | include/linux/eventpoll.h | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h index ea9ca0e4172a..de1c738aa8ad 100644 --- a/include/linux/eventpoll.h +++ b/include/linux/eventpoll.h @@ -39,12 +39,16 @@ 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. + * Fast check to skip the slow path in the common case where the + * file was never attached to an epoll. Safe without file->f_lock + * because every f_ep writer excludes a concurrent __fput() on + * @file: + * - ep_insert() requires the file alive (refcount > 0); + * - ep_remove() holds @file pinned via epi_fget() across the + * write; + * - eventpoll_release_file() runs from __fput() itself. + * We are in __fput() here, so none of those can race us: a NULL + * observation truly means no epoll path has work left on @file. */ if (likely(!READ_ONCE(file->f_ep))) return; @@ -57,8 +61,16 @@ static inline void eventpoll_release(struct file *file) eventpoll_release_file(file); } +struct epoll_key { + struct file *file; + int fd; +} __packed; + +int do_epoll_ctl_file(struct file *f, int op, struct epoll_key *tf, + struct epoll_event *epds, bool nonblock); int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds, bool nonblock); +bool is_file_epoll(struct file *f); /* Tells if the epoll_ctl(2) operation needs an event copy from userspace */ static inline int ep_op_has_event(int op) |