Copyright (C) 2022 Jens Axboe <[email protected]>

SPDX-License-Identifier: LGPL-2.0-or-later

io_uring_prep_timeoute_update - prepare a request to update an existing timeout

 #include <liburing.h> 

 "void io_uring_prep_timeout_update(struct io_uring_sqe *" sqe ","  " struct __kernel_timespec *" ts ","  " __u64 " user_data ","  " unsigned " flags ");" 

 "void io_uring_prep_timeout_remove(struct io_uring_sqe *" sqe ","  " __u64 " user_data ","  " unsigned " flags ");" 

These functions modify or cancel an existing timeout request. The submission queue entry sqe is setup to arm a timeout update or removal specified by user_data and with modifier flags given by flags . Additionally, the update request includes a ts structure, which contains new timeout information. For an update request, the flags member may contain a bitmask of the following values:

IORING_TIMEOUT_ABS The value specified in ts is an absolute value rather than a relative one.

IORING_TIMEOUT_BOOTTIME The boottime clock source should be used.

IORING_TIMEOUT_REALTIME The realtime clock source should be used.

IORING_TIMEOUT_ETIME_SUCCESS Consider an expired timeout a success in terms of the posted completion. Normally a timeout that triggers would return in a -ETIME CQE res value.

None These are the errors that are reported in the CQE res field. On success, 0 is returned.

-ENOENT The timeout identified by user_data could not be found. It may be invalid, or triggered before the update or removal request was processed.

-EALREADY The timeout identified by user_data is already firing and cannot be canceled.

-EINVAL One of the fields set in the SQE was invalid. For example, two clocksources where given, or the specified timeout seconds or nanoseconds where < 0.

-EFAULT io_uring was unable to access the data specified by ts .

As with any request that passes in data in a struct, that data must remain valid until the request has been successfully submitted. It need not remain valid until completion. Once a request has been submitted, the in-kernel state is stable. Very early kernels (5.4 and earlier) required state to be stable until the completion occurred. Applications can test for this behavior by inspecting the IORING_FEAT_SUBMIT_STABLE flag passed back from io_uring_queue_init_params (3). io_uring_get_sqe (3), io_uring_submit (3), io_uring_prep_timeout (3)