---
name: "io_uring_prep_timeout_update"
section: "3"
platform: "linux"
package: "liburing"
version: "2.15-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/io_uring_prep_timeout_update"
---

# io\_uring\_prep\_timeout\_update(3)

prepare a request to update an existing timeout

## 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)](/io_uring_queue_init_params/3.md).

## SEE ALSO

[**io\_uring\_get\_sqe**(3)](/io_uring_get_sqe/3.md), [**io\_uring\_submit**(3)](/io_uring_submit/3.md), [**io\_uring\_prep\_timeout**(3)](/io_uring_prep_timeout/3.md)