| .\" Copyright (C) 2022 Jens Axboe <axboe@kernel.dk> |
| .\" |
| .\" SPDX-License-Identifier: LGPL-2.0-or-later |
| .\" |
| .TH io_uring_buf_ring_cq_advance 3 "May 18, 2022" "liburing-2.2" "liburing Manual" |
| .SH NAME |
| io_uring_buf_ring_cq_advance \- advance index of provided buffer and CQ ring |
| .SH SYNOPSIS |
| .nf |
| .B #include <liburing.h> |
| .PP |
| .BI "void io_uring_buf_ring_cq_advance(struct io_uring *" ring ", |
| .BI " struct io_uring_buf_ring *" br ", |
| .BI " int " count ");" |
| .PP |
| .BI "void __io_uring_buf_ring_cq_advance(struct io_uring *" ring ", |
| .BI " struct io_uring_buf_ring *" br ", |
| .BI " int " cq_count ", |
| .BI " int " buf_count ");" |
| .fi |
| .SH DESCRIPTION |
| .PP |
| The |
| .BR io_uring_buf_ring_cq_advance (3) |
| commits |
| .I count |
| previously added buffers to the shared buffer ring |
| .IR br , |
| making them visible to the kernel and hence consumable. This passes ownership |
| of the buffer to the ring. At the same time, it advances the CQ ring of |
| .I ring |
| by |
| .I count |
| amount. This effectively bundles both a |
| .BR io_uring_buf_ring_advance (3) |
| call and a |
| .BR io_uring_cq_advance (3) |
| into one operation. Since updating either ring index entails a store memory |
| barrier, doing both at once is more efficient. |
| |
| The |
| .BR __io_uring_buf_ring_cq_advance (3) |
| function performs the same operation, except it splits the counts into two |
| separate values. It advances the CQ ring by |
| .I cq_count |
| entries, and the buffer ring by |
| .I buf_count |
| entries rather than increment both by the same value. |
| |
| .SH RETURN VALUE |
| None |
| .SH SEE ALSO |
| .BR io_uring_register_buf_ring (3), |
| .BR io_uring_buf_ring_add (3), |
| .BR io_uring_buf_ring_advance (3) |
