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io_uring/net: add IORING_ACCEPT_POLL_FIRST flag 

Similarly to how polling first is supported for receive, it makes sense
to provide the same for accept. An accept operation does a lot of
expensive setup, like allocating an fd, a socket/inode, etc. If no
connection request is already pending, this is wasted and will just be
cleaned up and freed, only to retry via the usual poll trigger.

Add IORING_ACCEPT_POLL_FIRST, which tells accept to only initiate the
accept request if poll says we have something to accept.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2024-05-08 08:17:50 -06:00
parent 7dcc758cca
commit d3da8e9859
2 changed files with 9 additions and 1 deletions
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1
include/uapi/linux/io_uring.h
View File

@ -380,6 +380,7 @@ enum io_uring_op {
*/
#define IORING_ACCEPT_MULTISHOT (1U << 0)
#define IORING_ACCEPT_DONTWAIT (1U << 1)
#define IORING_ACCEPT_POLL_FIRST (1U << 2)
/*
* IORING_OP_MSG_RING command types, stored in sqe->addr

9
io_uring/net.c
View File

@ -1487,6 +1487,9 @@ void io_sendrecv_fail(struct io_kiocb *req)
req->cqe.flags |= IORING_CQE_F_MORE;
}
#define ACCEPT_FLAGS (IORING_ACCEPT_MULTISHOT | IORING_ACCEPT_DONTWAIT | \
IORING_ACCEPT_POLL_FIRST)
int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_accept *accept = io_kiocb_to_cmd(req, struct io_accept);
@ -1499,7 +1502,7 @@ int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
accept->flags = READ_ONCE(sqe->accept_flags);
accept->nofile = rlimit(RLIMIT_NOFILE);
accept->iou_flags = READ_ONCE(sqe->ioprio);
if (accept->iou_flags & ~(IORING_ACCEPT_MULTISHOT | IORING_ACCEPT_DONTWAIT))
if (accept->iou_flags & ~ACCEPT_FLAGS)
return -EINVAL;
accept->file_slot = READ_ONCE(sqe->file_index);
@ -1530,6 +1533,10 @@ int io_accept(struct io_kiocb *req, unsigned int issue_flags)
struct file *file;
int ret, fd;
if (!(req->flags & REQ_F_POLLED) &&
accept->iou_flags & IORING_ACCEPT_POLL_FIRST)
return -EAGAIN;
retry:
if (!fixed) {
fd = __get_unused_fd_flags(accept->flags, accept->nofile);