busy_poll.h

  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
 27static inline bool napi_id_valid(unsigned int napi_id)
 28{
 29	return napi_id >= MIN_NAPI_ID;
 30}
 31
 32#define BUSY_POLL_BUDGET 8
 33
 34#ifdef CONFIG_NET_RX_BUSY_POLL
 35
 36struct napi_struct;
 37extern unsigned int sysctl_net_busy_read __read_mostly;
 38extern unsigned int sysctl_net_busy_poll __read_mostly;
 39
 40static inline bool net_busy_loop_on(void)
 41{
 42	return READ_ONCE(sysctl_net_busy_poll);
 43}
 44
 45static inline bool sk_can_busy_loop(const struct sock *sk)
 46{
 47	return READ_ONCE(sk->sk_ll_usec) && !signal_pending(current);
 48}
 49
 50bool sk_busy_loop_end(void *p, unsigned long start_time);
 51
 52void napi_busy_loop(unsigned int napi_id,
 53		    bool (*loop_end)(void *, unsigned long),
 54		    void *loop_end_arg, bool prefer_busy_poll, u16 budget);
 55
 56void napi_busy_loop_rcu(unsigned int napi_id,
 57			bool (*loop_end)(void *, unsigned long),
 58			void *loop_end_arg, bool prefer_busy_poll, u16 budget);
 59
 60void napi_suspend_irqs(unsigned int napi_id);
 61void napi_resume_irqs(unsigned int napi_id);
 62
 63#else /* CONFIG_NET_RX_BUSY_POLL */
 64static inline unsigned long net_busy_loop_on(void)
 65{
 66	return 0;
 67}
 68
 69static inline bool sk_can_busy_loop(struct sock *sk)
 70{
 71	return false;
 72}
 73
 74#endif /* CONFIG_NET_RX_BUSY_POLL */
 75
 76static inline unsigned long busy_loop_current_time(void)
 77{
 78#ifdef CONFIG_NET_RX_BUSY_POLL
 79	return (unsigned long)(ktime_get_ns() >> 10);
 80#else
 81	return 0;
 82#endif
 83}
 84
 85/* in poll/select we use the global sysctl_net_ll_poll value */
 86static inline bool busy_loop_timeout(unsigned long start_time)
 87{
 88#ifdef CONFIG_NET_RX_BUSY_POLL
 89	unsigned long bp_usec = READ_ONCE(sysctl_net_busy_poll);
 90
 91	if (bp_usec) {
 92		unsigned long end_time = start_time + bp_usec;
 93		unsigned long now = busy_loop_current_time();
 94
 95		return time_after(now, end_time);
 96	}
 97#endif
 98	return true;
 99}
100
101static inline bool sk_busy_loop_timeout(struct sock *sk,
102					unsigned long start_time)
103{
104#ifdef CONFIG_NET_RX_BUSY_POLL
105	unsigned long bp_usec = READ_ONCE(sk->sk_ll_usec);
106
107	if (bp_usec) {
108		unsigned long end_time = start_time + bp_usec;
109		unsigned long now = busy_loop_current_time();
110
111		return time_after(now, end_time);
112	}
113#endif
114	return true;
115}
116
117static inline void sk_busy_loop(struct sock *sk, int nonblock)
118{
119#ifdef CONFIG_NET_RX_BUSY_POLL
120	unsigned int napi_id = READ_ONCE(sk->sk_napi_id);
121
122	if (napi_id_valid(napi_id))
123		napi_busy_loop(napi_id, nonblock ? NULL : sk_busy_loop_end, sk,
124			       READ_ONCE(sk->sk_prefer_busy_poll),
125			       READ_ONCE(sk->sk_busy_poll_budget) ?: BUSY_POLL_BUDGET);
126#endif
127}
128
129/* used in the NIC receive handler to mark the skb */
130static inline void __skb_mark_napi_id(struct sk_buff *skb,
131				      const struct gro_node *gro)
132{
133#ifdef CONFIG_NET_RX_BUSY_POLL
134	/* If the skb was already marked with a valid NAPI ID, avoid overwriting
135	 * it.
136	 */
137	if (!napi_id_valid(skb->napi_id))
138		skb->napi_id = gro->cached_napi_id;
139#endif
140}
141
142static inline void skb_mark_napi_id(struct sk_buff *skb,
143				    const struct napi_struct *napi)
144{
145	__skb_mark_napi_id(skb, &napi->gro);
146}
147
148/* used in the protocol handler to propagate the napi_id to the socket */
149static inline void sk_mark_napi_id(struct sock *sk, const struct sk_buff *skb)
150{
151#ifdef CONFIG_NET_RX_BUSY_POLL
152	if (unlikely(READ_ONCE(sk->sk_napi_id) != skb->napi_id))
153		WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
154#endif
155	sk_rx_queue_update(sk, skb);
156}
157
158/* Variant of sk_mark_napi_id() for passive flow setup,
159 * as sk->sk_napi_id and sk->sk_rx_queue_mapping content
160 * needs to be set.
161 */
162static inline void sk_mark_napi_id_set(struct sock *sk,
163				       const struct sk_buff *skb)
164{
165#ifdef CONFIG_NET_RX_BUSY_POLL
166	WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
167#endif
168	sk_rx_queue_set(sk, skb);
169}
170
171static inline void __sk_mark_napi_id_once(struct sock *sk, unsigned int napi_id)
172{
173#ifdef CONFIG_NET_RX_BUSY_POLL
174	if (!READ_ONCE(sk->sk_napi_id))
175		WRITE_ONCE(sk->sk_napi_id, napi_id);
176#endif
177}
178
179/* variant used for unconnected sockets */
180static inline void sk_mark_napi_id_once(struct sock *sk,
181					const struct sk_buff *skb)
182{
183#ifdef CONFIG_NET_RX_BUSY_POLL
184	__sk_mark_napi_id_once(sk, skb->napi_id);
185#endif
186}
187
188#endif /* _LINUX_NET_BUSY_POLL_H */