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
 51#else /* CONFIG_NET_RX_BUSY_POLL */
 52static inline unsigned long net_busy_loop_on(void)
 53{
 54	return 0;
 55}
 56
 57static inline bool sk_can_busy_loop(struct sock *sk)
 58{
 59	return false;
 60}
 61
 62#endif /* CONFIG_NET_RX_BUSY_POLL */
 63
 64static inline unsigned long busy_loop_current_time(void)
 65{
 66#ifdef CONFIG_NET_RX_BUSY_POLL
 67	return (unsigned long)(local_clock() >> 10);
 68#else
 69	return 0;
 70#endif
 71}
 72
 73/* in poll/select we use the global sysctl_net_ll_poll value */
 74static inline bool busy_loop_timeout(unsigned long start_time)
 75{
 76#ifdef CONFIG_NET_RX_BUSY_POLL
 77	unsigned long bp_usec = READ_ONCE(sysctl_net_busy_poll);
 78
 79	if (bp_usec) {
 80		unsigned long end_time = start_time + bp_usec;
 81		unsigned long now = busy_loop_current_time();
 82
 83		return time_after(now, end_time);
 84	}
 85#endif
 86	return true;
 87}
 88
 89static inline bool sk_busy_loop_timeout(struct sock *sk,
 90					unsigned long start_time)
 91{
 92#ifdef CONFIG_NET_RX_BUSY_POLL
 93	unsigned long bp_usec = READ_ONCE(sk->sk_ll_usec);
 94
 95	if (bp_usec) {
 96		unsigned long end_time = start_time + bp_usec;
 97		unsigned long now = busy_loop_current_time();
 98
 99		return time_after(now, end_time);
100	}
101#endif
102	return true;
103}
104
105static inline void sk_busy_loop(struct sock *sk, int nonblock)
106{
107#ifdef CONFIG_NET_RX_BUSY_POLL
108	unsigned int napi_id = READ_ONCE(sk->sk_napi_id);
109
110	if (napi_id >= MIN_NAPI_ID)
111		napi_busy_loop(napi_id, nonblock ? NULL : sk_busy_loop_end, sk,
112			       READ_ONCE(sk->sk_prefer_busy_poll),
113			       READ_ONCE(sk->sk_busy_poll_budget) ?: BUSY_POLL_BUDGET);
114#endif
115}
116
117/* used in the NIC receive handler to mark the skb */
118static inline void skb_mark_napi_id(struct sk_buff *skb,
119				    struct napi_struct *napi)
120{
121#ifdef CONFIG_NET_RX_BUSY_POLL
122	/* If the skb was already marked with a valid NAPI ID, avoid overwriting
123	 * it.
124	 */
125	if (skb->napi_id < MIN_NAPI_ID)
126		skb->napi_id = napi->napi_id;
127#endif
128}
129
130/* used in the protocol hanlder to propagate the napi_id to the socket */
131static inline void sk_mark_napi_id(struct sock *sk, const struct sk_buff *skb)
132{
133#ifdef CONFIG_NET_RX_BUSY_POLL
134	if (unlikely(READ_ONCE(sk->sk_napi_id) != skb->napi_id))
135		WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
136#endif
137	sk_rx_queue_update(sk, skb);
138}
139
140/* Variant of sk_mark_napi_id() for passive flow setup,
141 * as sk->sk_napi_id and sk->sk_rx_queue_mapping content
142 * needs to be set.
143 */
144static inline void sk_mark_napi_id_set(struct sock *sk,
145				       const struct sk_buff *skb)
146{
147#ifdef CONFIG_NET_RX_BUSY_POLL
148	WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
149#endif
150	sk_rx_queue_set(sk, skb);
151}
152
153static inline void __sk_mark_napi_id_once(struct sock *sk, unsigned int napi_id)
154{
155#ifdef CONFIG_NET_RX_BUSY_POLL
156	if (!READ_ONCE(sk->sk_napi_id))
157		WRITE_ONCE(sk->sk_napi_id, napi_id);
158#endif
159}
160
161/* variant used for unconnected sockets */
162static inline void sk_mark_napi_id_once(struct sock *sk,
163					const struct sk_buff *skb)
164{
165#ifdef CONFIG_NET_RX_BUSY_POLL
166	__sk_mark_napi_id_once(sk, skb->napi_id);
167#endif
168}
169
170static inline void sk_mark_napi_id_once_xdp(struct sock *sk,
171					    const struct xdp_buff *xdp)
172{
173#ifdef CONFIG_NET_RX_BUSY_POLL
174	__sk_mark_napi_id_once(sk, xdp->rxq->napi_id);
175#endif
176}
177
178#endif /* _LINUX_NET_BUSY_POLL_H */