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
 55void napi_suspend_irqs(unsigned int napi_id);
 56void napi_resume_irqs(unsigned int napi_id);
 57
 58#else /* CONFIG_NET_RX_BUSY_POLL */
 59static inline unsigned long net_busy_loop_on(void)
 60{
 61	return 0;
 62}
 63
 64static inline bool sk_can_busy_loop(struct sock *sk)
 65{
 66	return false;
 67}
 68
 69#endif /* CONFIG_NET_RX_BUSY_POLL */
 70
 71static inline unsigned long busy_loop_current_time(void)
 72{
 73#ifdef CONFIG_NET_RX_BUSY_POLL
 74	return (unsigned long)(ktime_get_ns() >> 10);
 75#else
 76	return 0;
 77#endif
 78}
 79
 80/* in poll/select we use the global sysctl_net_ll_poll value */
 81static inline bool busy_loop_timeout(unsigned long start_time)
 82{
 83#ifdef CONFIG_NET_RX_BUSY_POLL
 84	unsigned long bp_usec = READ_ONCE(sysctl_net_busy_poll);
 85
 86	if (bp_usec) {
 87		unsigned long end_time = start_time + bp_usec;
 88		unsigned long now = busy_loop_current_time();
 89
 90		return time_after(now, end_time);
 91	}
 92#endif
 93	return true;
 94}
 95
 96static inline bool sk_busy_loop_timeout(struct sock *sk,
 97					unsigned long start_time)
 98{
 99#ifdef CONFIG_NET_RX_BUSY_POLL
100	unsigned long bp_usec = READ_ONCE(sk->sk_ll_usec);
101
102	if (bp_usec) {
103		unsigned long end_time = start_time + bp_usec;
104		unsigned long now = busy_loop_current_time();
105
106		return time_after(now, end_time);
107	}
108#endif
109	return true;
110}
111
112static inline void sk_busy_loop(struct sock *sk, int nonblock)
113{
114#ifdef CONFIG_NET_RX_BUSY_POLL
115	unsigned int napi_id = READ_ONCE(sk->sk_napi_id);
116
117	if (napi_id >= MIN_NAPI_ID)
118		napi_busy_loop(napi_id, nonblock ? NULL : sk_busy_loop_end, sk,
119			       READ_ONCE(sk->sk_prefer_busy_poll),
120			       READ_ONCE(sk->sk_busy_poll_budget) ?: BUSY_POLL_BUDGET);
121#endif
122}
123
124/* used in the NIC receive handler to mark the skb */
125static inline void skb_mark_napi_id(struct sk_buff *skb,
126				    struct napi_struct *napi)
127{
128#ifdef CONFIG_NET_RX_BUSY_POLL
129	/* If the skb was already marked with a valid NAPI ID, avoid overwriting
130	 * it.
131	 */
132	if (skb->napi_id < MIN_NAPI_ID)
133		skb->napi_id = napi->napi_id;
134#endif
135}
136
137/* used in the protocol handler to propagate the napi_id to the socket */
138static inline void sk_mark_napi_id(struct sock *sk, const struct sk_buff *skb)
139{
140#ifdef CONFIG_NET_RX_BUSY_POLL
141	if (unlikely(READ_ONCE(sk->sk_napi_id) != skb->napi_id))
142		WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
143#endif
144	sk_rx_queue_update(sk, skb);
145}
146
147/* Variant of sk_mark_napi_id() for passive flow setup,
148 * as sk->sk_napi_id and sk->sk_rx_queue_mapping content
149 * needs to be set.
150 */
151static inline void sk_mark_napi_id_set(struct sock *sk,
152				       const struct sk_buff *skb)
153{
154#ifdef CONFIG_NET_RX_BUSY_POLL
155	WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
156#endif
157	sk_rx_queue_set(sk, skb);
158}
159
160static inline void __sk_mark_napi_id_once(struct sock *sk, unsigned int napi_id)
161{
162#ifdef CONFIG_NET_RX_BUSY_POLL
163	if (!READ_ONCE(sk->sk_napi_id))
164		WRITE_ONCE(sk->sk_napi_id, napi_id);
165#endif
166}
167
168/* variant used for unconnected sockets */
169static inline void sk_mark_napi_id_once(struct sock *sk,
170					const struct sk_buff *skb)
171{
172#ifdef CONFIG_NET_RX_BUSY_POLL
173	__sk_mark_napi_id_once(sk, skb->napi_id);
174#endif
175}
176
177#endif /* _LINUX_NET_BUSY_POLL_H */