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io_uring: add support for level triggered poll

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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: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2022-05-27 10:55:07 -06:00
parent d9b57aa3cf
commit b9ba8a4463
2 changed files with 13 additions and 5 deletions
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3
include/uapi/linux/io_uring.h
View File

@ -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.

15
io_uring/poll.c
View File

@ -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;