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
31 struct napi_struct;
32 extern unsigned int sysctl_net_busy_read __read_mostly;
33 extern unsigned int sysctl_net_busy_poll __read_mostly;
34
35 static inline bool net_busy_loop_on(void)
36 {
37 return READ_ONCE(sysctl_net_busy_poll);
38 }
39
40 static inline bool sk_can_busy_loop(const struct sock *sk)
41 {
42 return READ_ONCE(sk->sk_ll_usec) && !signal_pending(current);
43 }
44
45 bool sk_busy_loop_end(void *p, unsigned long start_time);
46
47 void 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
51 void 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 */
56 static inline unsigned long net_busy_loop_on(void)
57 {
58 return 0;
59 }
60
61 static inline bool sk_can_busy_loop(struct sock *sk)
62 {
63 return false;
64 }
65
66 #endif /* CONFIG_NET_RX_BUSY_POLL */
67
68 static inline unsigned long busy_loop_current_time(void)
69 {
70 #ifdef CONFIG_NET_RX_BUSY_POLL
71 return (unsigned long)(ktime_get_ns() >> 10);
72 #else
73 return 0;
74 #endif
75 }
76
77 /* in poll/select we use the global sysctl_net_ll_poll value */
78 static 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
93 static 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
109 static 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, nonblock ? NULL : sk_busy_loop_end, 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 */
122 static 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 */
135 static 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 */
148 static 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
157 static 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 */
166 static 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, skb->napi_id);
171 #endif
172 }
173
174 static 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, xdp->rxq->napi_id);
179 #endif
180 }
181
182 #endif /* _LINUX_NET_BUSY_POLL_H */
183
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