1/* include/net/xdp.h
 2 *
 3 * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
 4 * Released under terms in GPL version 2.  See COPYING.
 5 */
 6#ifndef __LINUX_NET_XDP_H__
 7#define __LINUX_NET_XDP_H__
 8
 9/**
10 * DOC: XDP RX-queue information
11 *
12 * The XDP RX-queue info (xdp_rxq_info) is associated with the driver
13 * level RX-ring queues.  It is information that is specific to how
14 * the driver have configured a given RX-ring queue.
15 *
16 * Each xdp_buff frame received in the driver carry a (pointer)
17 * reference to this xdp_rxq_info structure.  This provides the XDP
18 * data-path read-access to RX-info for both kernel and bpf-side
19 * (limited subset).
20 *
21 * For now, direct access is only safe while running in NAPI/softirq
22 * context.  Contents is read-mostly and must not be updated during
23 * driver NAPI/softirq poll.
24 *
25 * The driver usage API is a register and unregister API.
26 *
27 * The struct is not directly tied to the XDP prog.  A new XDP prog
28 * can be attached as long as it doesn't change the underlying
29 * RX-ring.  If the RX-ring does change significantly, the NIC driver
30 * naturally need to stop the RX-ring before purging and reallocating
31 * memory.  In that process the driver MUST call unregistor (which
32 * also apply for driver shutdown and unload).  The register API is
33 * also mandatory during RX-ring setup.
34 */
35
36struct xdp_rxq_info {
37	struct net_device *dev;
38	u32 queue_index;
39	u32 reg_state;
40} ____cacheline_aligned; /* perf critical, avoid false-sharing */
41
42int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
43		     struct net_device *dev, u32 queue_index);
44void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq);
45void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq);
46bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
47
48#endif /* __LINUX_NET_XDP_H__ */