LXR linux/include/net/busy

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