在 2019年9月18日，03:38，Jens Axboe <axboe@xxxxxxxxx> 写道：
>
> There's been a few requests for functionality similar to io_getevents()
> and epoll_wait(), where the user can specify a timeout for waiting on
> events. I deliberately did not add support for this through the system
> call initially to avoid overloading the args, but I can see that the use
> cases for this are valid.
>
> This adds support for IORING_OP_TIMEOUT. If a user wants to get woken
> when waiting for events, simply submit one of these timeout commands
> with your wait call (or before). This ensures that the application
> sleeping on the CQ ring waiting for events will get woken. The timeout
> command is passed in as a pointer to a struct timespec. Timeouts are
> relative.
>
> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
>
> ---
>
> V2
>
> - Ensure any timeout will result in a return to userspace from
> io_cqring_wait().
> - Improve commit message
> - Add ->file to struct io_timeout
> - Kill separate 'kt' value, use timespec_to_kt() directly
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 0dadbdbead0f..02db09b89e83 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -216,6 +216,7 @@ struct io_ring_ctx {
> struct wait_queue_head cq_wait;
> struct fasync_struct *cq_fasync;
> struct eventfd_ctx *cq_ev_fd;
> + atomic_t cq_timeouts;
> } ____cacheline_aligned_in_smp;
>
> struct io_rings *rings;
> @@ -283,6 +284,11 @@ struct io_poll_iocb {
> struct wait_queue_entry wait;
> };
>
> +struct io_timeout {
> + struct file *file;
> + struct hrtimer timer;
> +};
> +
> /*
> * NOTE! Each of the iocb union members has the file pointer
> * as the first entry in their struct definition. So you can
> @@ -294,6 +300,7 @@ struct io_kiocb {
> struct file *file;
> struct kiocb rw;
> struct io_poll_iocb poll;
> + struct io_timeout timeout;
> };
>
> struct sqe_submit submit;
> @@ -1765,6 +1772,35 @@ static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe)
> return ipt.error;
> }
>
> +static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer)
> +{
> + struct io_kiocb *req;
> +
> + req = container_of(timer, struct io_kiocb, timeout.timer);
> + atomic_inc(&req->ctx->cq_timeouts);
> + io_cqring_add_event(req->ctx, req->user_data, 0);
> + io_put_req(req);
> + return HRTIMER_NORESTART;
> +}
> +
> +static int io_timeout(struct io_kiocb *req, const struct io_uring_sqe *sqe)
> +{
> + struct timespec ts;
> +
> + if (sqe->flags || sqe->ioprio || sqe->off || sqe->buf_index)
> + return -EINVAL;
> + if (sqe->len != 1)
> + return -EINVAL;
Should we need this?
if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
return -EINVAL;
Otherwise it will be queue by io_iopoll_req_issued.
> + if (copy_from_user(&ts, (void __user *) sqe->addr, sizeof(ts)))
> + return -EFAULT;
> +
> + hrtimer_init(&req->timeout.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> + req->timeout.timer.function = io_timeout_fn;
> + hrtimer_start(&req->timeout.timer, timespec_to_ktime(ts),
> + HRTIMER_MODE_REL);
> + return 0;
> +}
> +
--
BR, Jackie Liu
