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#ifdef CONFIG_NET_RX_BUSY_POLL
27
28struct napi_struct;
29extern unsigned int sysctl_net_busy_read __read_mostly;
30extern unsigned int sysctl_net_busy_poll __read_mostly;
31
32static inline bool net_busy_loop_on(void)
33{
34	return READ_ONCE(sysctl_net_busy_poll);
35}
36
37static inline bool sk_can_busy_loop(const struct sock *sk)
38{
39	return READ_ONCE(sk->sk_ll_usec) && !signal_pending(current);
40}
41
42bool sk_busy_loop_end(void *p, unsigned long start_time);
43
44void napi_busy_loop(unsigned int napi_id,
45		    bool (*loop_end)(void *, unsigned long),
46		    void *loop_end_arg);
47
48#else /* CONFIG_NET_RX_BUSY_POLL */
49static inline unsigned long net_busy_loop_on(void)
50{
51	return 0;
52}
53
54static inline bool sk_can_busy_loop(struct sock *sk)
55{
56	return false;
57}
58
59#endif /* CONFIG_NET_RX_BUSY_POLL */
60
61static inline unsigned long busy_loop_current_time(void)
62{
63#ifdef CONFIG_NET_RX_BUSY_POLL
64	return (unsigned long)(local_clock() >> 10);
65#else
66	return 0;
67#endif
68}
69
70/* in poll/select we use the global sysctl_net_ll_poll value */
71static inline bool busy_loop_timeout(unsigned long start_time)
72{
73#ifdef CONFIG_NET_RX_BUSY_POLL
74	unsigned long bp_usec = READ_ONCE(sysctl_net_busy_poll);
75
76	if (bp_usec) {
77		unsigned long end_time = start_time + bp_usec;
78		unsigned long now = busy_loop_current_time();
79
80		return time_after(now, end_time);
81	}
82#endif
83	return true;
84}
85
86static inline bool sk_busy_loop_timeout(struct sock *sk,
87					unsigned long start_time)
88{
89#ifdef CONFIG_NET_RX_BUSY_POLL
90	unsigned long bp_usec = READ_ONCE(sk->sk_ll_usec);
91
92	if (bp_usec) {
93		unsigned long end_time = start_time + bp_usec;
94		unsigned long now = busy_loop_current_time();
95
96		return time_after(now, end_time);
97	}
98#endif
99	return true;
100}
101
102static inline void sk_busy_loop(struct sock *sk, int nonblock)
103{
104#ifdef CONFIG_NET_RX_BUSY_POLL
105	unsigned int napi_id = READ_ONCE(sk->sk_napi_id);
106
107	if (napi_id >= MIN_NAPI_ID)
108		napi_busy_loop(napi_id, nonblock ? NULL : sk_busy_loop_end, sk);
109#endif
110}
111
112/* used in the NIC receive handler to mark the skb */
113static inline void skb_mark_napi_id(struct sk_buff *skb,
114				    struct napi_struct *napi)
115{
116#ifdef CONFIG_NET_RX_BUSY_POLL
117	/* If the skb was already marked with a valid NAPI ID, avoid overwriting
118	 * it.
119	 */
120	if (skb->napi_id < MIN_NAPI_ID)
121		skb->napi_id = napi->napi_id;
122#endif
123}
124
125/* used in the protocol hanlder to propagate the napi_id to the socket */
126static inline void sk_mark_napi_id(struct sock *sk, const struct sk_buff *skb)
127{
128#ifdef CONFIG_NET_RX_BUSY_POLL
129	WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
130#endif
131	sk_rx_queue_set(sk, skb);
132}
133
134/* variant used for unconnected sockets */
135static inline void sk_mark_napi_id_once(struct sock *sk,
136					const struct sk_buff *skb)
137{
138#ifdef CONFIG_NET_RX_BUSY_POLL
139	if (!READ_ONCE(sk->sk_napi_id))
140		WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
141#endif
142}
143
144#endif /* _LINUX_NET_BUSY_POLL_H */
145