When epfd is polled from userspace and item is being modified: 1. Update user item with new pointer or poll flags. 2. Add event to user ring if needed.
Signed-off-by: Roman Penyaev <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Davidlohr Bueso <[email protected]> Cc: Jason Baron <[email protected]> Cc: Al Viro <[email protected]> Cc: "Paul E. McKenney" <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Andrea Parri <[email protected]> Cc: [email protected] Cc: [email protected] --- fs/eventpoll.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index b9f51f4b94e7..3c3721c315a7 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -2058,6 +2058,8 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, static int ep_modify(struct eventpoll *ep, struct epitem *epi, const struct epoll_event *event) { + struct epoll_uitem *uitem; + __poll_t revents; int pwake = 0; poll_table pt; @@ -2072,6 +2074,13 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, */ epi->event.events = event->events; /* need barrier below */ epi->event.data = event->data; /* protected by mtx */ + + /* Update user item, barrier is below */ + if (ep_polled_by_user(ep)) { + uitem = &ep->user_header->items[epi->bit]; + uitem->event = *event; + } + if (epi->event.events & EPOLLWAKEUP) { if (!ep_has_wakeup_source(epi)) ep_create_wakeup_source(epi); @@ -2105,12 +2114,19 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, * If the item is "hot" and it is not registered inside the ready * list, push it inside. */ - if (ep_item_poll(epi, &pt, 1)) { + revents = ep_item_poll(epi, &pt, 1); + if (revents) { + bool added = false; + write_lock_irq(&ep->lock); - if (!ep_is_linked(epi)) { + if (ep_polled_by_user(ep)) + added = ep_add_event_to_uring(epi, revents); + else if (!ep_is_linked(epi)) { list_add_tail(&epi->rdllink, &ep->rdllist); ep_pm_stay_awake(epi); - + added = true; + } + if (added) { /* Notify waiting tasks that events are available */ if (waitqueue_active(&ep->wq)) wake_up(&ep->wq); -- 2.19.1
