1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * net busy poll support
4 * Copyright(c) 2013 Intel Corporation.
5 *
6 * Author: Eliezer Tamir
7 *
8 * Contact Information:
9 * e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>
10 */
11
12#ifndef _LINUX_NET_BUSY_POLL_H
13#define _LINUX_NET_BUSY_POLL_H
14
15#include <linux/netdevice.h>
16#include <linux/sched/clock.h>
17#include <linux/sched/signal.h>
18#include <net/ip.h>
19#include <net/xdp.h>
20
21/* 0 - Reserved to indicate value not set
22 * 1..NR_CPUS - Reserved for sender_cpu
23 * NR_CPUS+1..~0 - Region available for NAPI IDs
24 */
25#define MIN_NAPI_ID ((unsigned int)(NR_CPUS + 1))
26
27#define BUSY_POLL_BUDGET 8
28
29#ifdef CONFIG_NET_RX_BUSY_POLL
30
31struct napi_struct;
32extern unsigned int sysctl_net_busy_read __read_mostly;
33extern unsigned int sysctl_net_busy_poll __read_mostly;
34
35static inline bool net_busy_loop_on(void)
36{
37 return READ_ONCE(sysctl_net_busy_poll);
38}
39
40static inline bool sk_can_busy_loop(const struct sock *sk)
41{
42 return READ_ONCE(sk->sk_ll_usec) && !signal_pending(current);
43}
44
45bool sk_busy_loop_end(void *p, unsigned long start_time);
46
47void napi_busy_loop(unsigned int napi_id,
48 bool (*loop_end)(void *, unsigned long),
49 void *loop_end_arg, bool prefer_busy_poll, u16 budget);
50
51void napi_busy_loop_rcu(unsigned int napi_id,
52 bool (*loop_end)(void *, unsigned long),
53 void *loop_end_arg, bool prefer_busy_poll, u16 budget);
54
55#else /* CONFIG_NET_RX_BUSY_POLL */
56static inline unsigned long net_busy_loop_on(void)
57{
58 return 0;
59}
60
61static inline bool sk_can_busy_loop(struct sock *sk)
62{
63 return false;
64}
65
66#endif /* CONFIG_NET_RX_BUSY_POLL */
67
68static inline unsigned long busy_loop_current_time(void)
69{
70#ifdef CONFIG_NET_RX_BUSY_POLL
71 return (unsigned long)(local_clock() >> 10);
72#else
73 return 0;
74#endif
75}
76
77/* in poll/select we use the global sysctl_net_ll_poll value */
78static inline bool busy_loop_timeout(unsigned long start_time)
79{
80#ifdef CONFIG_NET_RX_BUSY_POLL
81 unsigned long bp_usec = READ_ONCE(sysctl_net_busy_poll);
82
83 if (bp_usec) {
84 unsigned long end_time = start_time + bp_usec;
85 unsigned long now = busy_loop_current_time();
86
87 return time_after(now, end_time);
88 }
89#endif
90 return true;
91}
92
93static inline bool sk_busy_loop_timeout(struct sock *sk,
94 unsigned long start_time)
95{
96#ifdef CONFIG_NET_RX_BUSY_POLL
97 unsigned long bp_usec = READ_ONCE(sk->sk_ll_usec);
98
99 if (bp_usec) {
100 unsigned long end_time = start_time + bp_usec;
101 unsigned long now = busy_loop_current_time();
102
103 return time_after(now, end_time);
104 }
105#endif
106 return true;
107}
108
109static inline void sk_busy_loop(struct sock *sk, int nonblock)
110{
111#ifdef CONFIG_NET_RX_BUSY_POLL
112 unsigned int napi_id = READ_ONCE(sk->sk_napi_id);
113
114 if (napi_id >= MIN_NAPI_ID)
115 napi_busy_loop(napi_id, loop_end: nonblock ? NULL : sk_busy_loop_end, loop_end_arg: sk,
116 READ_ONCE(sk->sk_prefer_busy_poll),
117 READ_ONCE(sk->sk_busy_poll_budget) ?: BUSY_POLL_BUDGET);
118#endif
119}
120
121/* used in the NIC receive handler to mark the skb */
122static inline void skb_mark_napi_id(struct sk_buff *skb,
123 struct napi_struct *napi)
124{
125#ifdef CONFIG_NET_RX_BUSY_POLL
126 /* If the skb was already marked with a valid NAPI ID, avoid overwriting
127 * it.
128 */
129 if (skb->napi_id < MIN_NAPI_ID)
130 skb->napi_id = napi->napi_id;
131#endif
132}
133
134/* used in the protocol hanlder to propagate the napi_id to the socket */
135static inline void sk_mark_napi_id(struct sock *sk, const struct sk_buff *skb)
136{
137#ifdef CONFIG_NET_RX_BUSY_POLL
138 if (unlikely(READ_ONCE(sk->sk_napi_id) != skb->napi_id))
139 WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
140#endif
141 sk_rx_queue_update(sk, skb);
142}
143
144/* Variant of sk_mark_napi_id() for passive flow setup,
145 * as sk->sk_napi_id and sk->sk_rx_queue_mapping content
146 * needs to be set.
147 */
148static inline void sk_mark_napi_id_set(struct sock *sk,
149 const struct sk_buff *skb)
150{
151#ifdef CONFIG_NET_RX_BUSY_POLL
152 WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
153#endif
154 sk_rx_queue_set(sk, skb);
155}
156
157static inline void __sk_mark_napi_id_once(struct sock *sk, unsigned int napi_id)
158{
159#ifdef CONFIG_NET_RX_BUSY_POLL
160 if (!READ_ONCE(sk->sk_napi_id))
161 WRITE_ONCE(sk->sk_napi_id, napi_id);
162#endif
163}
164
165/* variant used for unconnected sockets */
166static inline void sk_mark_napi_id_once(struct sock *sk,
167 const struct sk_buff *skb)
168{
169#ifdef CONFIG_NET_RX_BUSY_POLL
170 __sk_mark_napi_id_once(sk, napi_id: skb->napi_id);
171#endif
172}
173
174static inline void sk_mark_napi_id_once_xdp(struct sock *sk,
175 const struct xdp_buff *xdp)
176{
177#ifdef CONFIG_NET_RX_BUSY_POLL
178 __sk_mark_napi_id_once(sk, napi_id: xdp->rxq->napi_id);
179#endif
180}
181
182#endif /* _LINUX_NET_BUSY_POLL_H */
183

source code of linux/include/net/busy_poll.h