Commit b9ba8a44 authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring: add support for level triggered poll 



By default, the POLL_ADD command does edge triggered poll - if we get
a non-zero mask on the initial poll attempt, we complete the request
successfully.

Support level triggered by always waiting for a notification, regardless
of whether or not the initial mask matches the file state.

Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent d9b57aa3

include/uapi/linux/io_uring.h

+3 −0
Original line number Diff line number Diff line
@@ -229,10 +229,13 @@ enum io_uring_op { 
 *

 * IORING_POLL_UPDATE		Update existing poll request, matching

 *				sqe->addr as the old user_data field.

 *

 * IORING_POLL_LEVEL		Level triggered poll.

 */

#define IORING_POLL_ADD_MULTI	(1U << 0)

#define IORING_POLL_UPDATE_EVENTS	(1U << 1)

#define IORING_POLL_UPDATE_USER_DATA	(1U << 2)

#define IORING_POLL_ADD_LEVEL		(1U << 3)



/*

 * ASYNC_CANCEL flags.

io_uring/poll.c

+10 −5
Original line number Diff line number Diff line
@@ -423,11 +423,13 @@ static int __io_arm_poll_handler(struct io_kiocb *req, 
	atomic_set(&req->poll_refs, 1);

	mask = vfs_poll(req->file, &ipt->pt) & poll->events;



	if (mask && (poll->events & EPOLLONESHOT)) {

	if (mask &&

	   ((poll->events & (EPOLLET|EPOLLONESHOT)) == (EPOLLET|EPOLLONESHOT))) {

		io_poll_remove_entries(req);

		/* no one else has access to the req, forget about the ref */

		return mask;

	}



	if (!mask && unlikely(ipt->error || !ipt->nr_entries)) {

		io_poll_remove_entries(req);

		if (!ipt->error)
@@ -439,7 +441,7 @@ static int __io_arm_poll_handler(struct io_kiocb *req, 
	io_poll_req_insert(req);

	spin_unlock(&ctx->completion_lock);



	if (mask) {

	if (mask && (poll->events & EPOLLET)) {

		/* can't multishot if failed, just queue the event we've got */

		if (unlikely(ipt->error || !ipt->nr_entries)) {

			poll->events |= EPOLLONESHOT;
@@ -475,7 +477,7 @@ int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags) 
	struct io_ring_ctx *ctx = req->ctx;

	struct async_poll *apoll;

	struct io_poll_table ipt;

	__poll_t mask = POLLPRI | POLLERR;

	__poll_t mask = POLLPRI | POLLERR | EPOLLET;

	int ret;



	if (!def->pollin && !def->pollout)
@@ -638,7 +640,10 @@ static __poll_t io_poll_parse_events(const struct io_uring_sqe *sqe, 
#endif

	if (!(flags & IORING_POLL_ADD_MULTI))

		events |= EPOLLONESHOT;

	return demangle_poll(events) | (events & (EPOLLEXCLUSIVE|EPOLLONESHOT));

	if (!(flags & IORING_POLL_ADD_LEVEL))

		events |= EPOLLET;

	return demangle_poll(events) |

		(events & (EPOLLEXCLUSIVE|EPOLLONESHOT|EPOLLET));

}



int io_poll_remove_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
@@ -679,7 +684,7 @@ int io_poll_add_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) 
	if (sqe->buf_index || sqe->off || sqe->addr)

		return -EINVAL;

	flags = READ_ONCE(sqe->len);

	if (flags & ~IORING_POLL_ADD_MULTI)

	if (flags & ~(IORING_POLL_ADD_MULTI|IORING_POLL_ADD_LEVEL))

		return -EINVAL;

	if ((flags & IORING_POLL_ADD_MULTI) && (req->flags & REQ_F_CQE_SKIP))

		return -EINVAL;