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 sysctl_net_busy_poll;
 35}
 36
 37static inline bool sk_can_busy_loop(const struct sock *sk)
 38{
 39	return 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 */