| .\" Copyright (C) 2022 Jens Axboe <axboe@kernel.dk> |
| .\" |
| .\" SPDX-License-Identifier: LGPL-2.0-or-later |
| .\" |
| .TH io_uring_buf_ring_add 3 "May 18, 2022" "liburing-2.2" "liburing Manual" |
| .SH NAME |
| io_uring_buf_ring_add \- add buffers to a shared buffer ring |
| .SH SYNOPSIS |
| .nf |
| .B #include <liburing.h> |
| .PP |
| .BI "void io_uring_buf_ring_add(struct io_uring_buf_ring *" br ", |
| .BI " void *" addr ", |
| .BI " unsigned int " len ", |
| .BI " unsigned short " bid ", |
| .BI " int " mask ", |
| .BI " int " buf_offset ");" |
| .fi |
| .SH DESCRIPTION |
| .PP |
| The |
| .BR io_uring_buf_ring_add (3) |
| adds a new buffer to the shared buffer ring |
| .IR br . |
| The buffer address is indicated by |
| .I addr |
| and is of |
| .I len |
| bytes of length. |
| .I bid |
| is the buffer ID, which will be returned in the CQE. |
| .I mask |
| is the size mask of the ring, available from |
| .BR io_uring_buf_ring_mask (3) . |
| .I buf_offset |
| is the offset to insert at from the current tail. If just one buffer is provided |
| before the ring tail is committed with |
| .BR io_uring_buf_ring_advance (3) |
| or |
| .BR io_uring_buf_ring_cq_advance (3), |
| then |
| .I buf_offset |
| should be 0. If buffers are provided in a loop before being committed, the |
| .I buf_offset |
| must be incremented by one for each buffer added. |
| |
| .SH RETURN VALUE |
| None |
| .SH NOTES |
| liburing (or the kernel, for that matter) doesn't care about what buffer ID maps |
| to what buffer, and in fact when recycling buffers after use, the application is |
| free to add a different buffer into the same buffer ID location. All that |
| matters is that the application knows what a given buffer ID in time corresponds |
| to in terms of virtual memory. There's no liburing or kernel assumption that |
| these mappings are persistent over time, they can very well be different every |
| time a given buffer ID is added to the provided buffer ring. |
| .SH SEE ALSO |
| .BR io_uring_register_buf_ring (3), |
| .BR io_uring_buf_ring_mask (3), |
| .BR io_uring_buf_ring_advance (3), |
| .BR io_uring_buf_ring_cq_advance (3) |
