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
30 struct napi_struct;
31 extern unsigned int sysctl_net_busy_read __read_mostly;
32 extern unsigned int sysctl_net_busy_poll __read_mostly;
33
net_busy_loop_on(void)34 static inline bool net_busy_loop_on(void)
35 {
36 return sysctl_net_busy_poll;
37 }
38
sk_can_busy_loop(const struct sock * sk)39 static inline bool sk_can_busy_loop(const struct sock *sk)
40 {
41 return READ_ONCE(sk->sk_ll_usec) && !signal_pending(current);
42 }
43
44 bool sk_busy_loop_end(void *p, unsigned long start_time);
45
46 void 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 */
net_busy_loop_on(void)51 static inline unsigned long net_busy_loop_on(void)
52 {
53 return 0;
54 }
55
sk_can_busy_loop(struct sock * sk)56 static inline bool sk_can_busy_loop(struct sock *sk)
57 {
58 return false;
59 }
60
61 #endif /* CONFIG_NET_RX_BUSY_POLL */
62
busy_loop_current_time(void)63 static 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 */
busy_loop_timeout(unsigned long start_time)73 static 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
sk_busy_loop_timeout(struct sock * sk,unsigned long start_time)88 static 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
sk_busy_loop(struct sock * sk,int nonblock)104 static 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 */
skb_mark_napi_id(struct sk_buff * skb,struct napi_struct * napi)117 static 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 */
sk_mark_napi_id(struct sock * sk,const struct sk_buff * skb)130 static inline void sk_mark_napi_id(struct sock *sk, const struct sk_buff *skb)
131 {
132 #ifdef CONFIG_NET_RX_BUSY_POLL
133 WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
134 #endif
135 sk_rx_queue_set(sk, skb);
136 }
137
__sk_mark_napi_id_once(struct sock * sk,unsigned int napi_id)138 static inline void __sk_mark_napi_id_once(struct sock *sk, unsigned int napi_id)
139 {
140 #ifdef CONFIG_NET_RX_BUSY_POLL
141 if (!READ_ONCE(sk->sk_napi_id))
142 WRITE_ONCE(sk->sk_napi_id, napi_id);
143 #endif
144 }
145
146 /* variant used for unconnected sockets */
sk_mark_napi_id_once(struct sock * sk,const struct sk_buff * skb)147 static inline void sk_mark_napi_id_once(struct sock *sk,
148 const struct sk_buff *skb)
149 {
150 #ifdef CONFIG_NET_RX_BUSY_POLL
151 __sk_mark_napi_id_once(sk, skb->napi_id);
152 #endif
153 }
154
sk_mark_napi_id_once_xdp(struct sock * sk,const struct xdp_buff * xdp)155 static inline void sk_mark_napi_id_once_xdp(struct sock *sk,
156 const struct xdp_buff *xdp)
157 {
158 #ifdef CONFIG_NET_RX_BUSY_POLL
159 __sk_mark_napi_id_once(sk, xdp->rxq->napi_id);
160 #endif
161 }
162
163 #endif /* _LINUX_NET_BUSY_POLL_H */
164
