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

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