.\" Copyright (C) 2021 Stefan Roesch .\" .\" SPDX-License-Identifier: LGPL-2.0-or-later .\" .TH io_uring_sqe_set_data 3 "November 15, 2021" "liburing-2.1" "liburing Manual" .SH NAME io_uring_sqe_set_data \- set user data for submission queue event .SH SYNOPSIS .nf .B #include .PP .BI "void io_uring_sqe_set_data(struct io_uring_sqe *" sqe "," .BI " void *" user_data ");" .BI " .BI "void io_uring_sqe_set_data64(struct io_uring_sqe *" sqe "," .BI " __u64 " data ");" .fi .SH DESCRIPTION .PP The .BR io_uring_sqe_set_data (3) function stores a .I user_data pointer with the submission queue entry .IR sqe . The .BR io_uring_sqe_set_data64 (3) function stores a 64-bit .I data value with the submission queue entry .IR sqe . After the caller has requested a submission queue entry (SQE) with .BR io_uring_get_sqe (3) , they can associate a data pointer or value with the SQE. Once the completion arrives, the function .BR io_uring_cqe_get_data (3) or .BR io_uring_cqe_get_data64 (3) can be called to retrieve the data pointer or value associated with the submitted request. Note that if neither of these functions are called, or the .I user_data field in the .IR sqe isn't set manually either, then the field may contain a value from a previous use of this sqe. If an application relies on always having a valid .I user_data value present, it must always assign one to each sqe. .SH RETURN VALUE None .SH SEE ALSO .BR io_uring_get_sqe (3), .BR io_uring_cqe_get_data (3)