include/net/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
  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
  30 struct napi_struct;
  31 extern unsigned int sysctl_net_busy_read __read_mostly;
  32 extern unsigned int sysctl_net_busy_poll __read_mostly;
  33
  34 static inline bool net_busy_loop_on(void)
  35 {
  36         return sysctl_net_busy_poll;
  37 }
  38
  39 static inline bool sk_can_busy_loop(const struct sock *sk)
  40 {
  41         return sk->sk_ll_usec && !signal_pending(current);
  42 }
  43
  44 bool sk_busy_loop_end(void *p, unsigned long start_time);
  45
  46 void 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 */
  51 static inline unsigned long net_busy_loop_on(void)
  52 {
  53         return 0;
  54 }
  55
  56 static inline bool sk_can_busy_loop(struct sock *sk)
  57 {
  58         return false;
  59 }
  60
  61 #endif /* CONFIG_NET_RX_BUSY_POLL */
  62
  63 static 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 */
  73 static 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
  88 static 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
 104 static 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 */
 117 static 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 */
 130 static 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
 138 static 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 */
 147 static 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
 155 static 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 */