io_uring_prep_timeout_update(3)

NAME

io_uring_prep_timeout_update - prepare a request to update an existing timeout

SYNOPSIS

#include <liburing.h>

void io_uring_prep_timeout_update(struct io_uring_sqe *sqe, const 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);

DESCRIPTION

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.

The timeout remove command does not currently accept any flags.

RETURN VALUE

None

ERRORS

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 were given, or the specified timeout seconds or nanoseconds were < 0.

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

NOTES

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).