LXR linux/include/net/busy

   1/*
   2 * net busy poll support
   3 * Copyright(c) 2013 Intel Corporation.
   4 *
   5 * This program is free software; you can redistribute it and/or modify it
   6 * under the terms and conditions of the GNU General Public License,
   7 * version 2, as published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope it will be useful, but WITHOUT
  10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12 * more details.
  13 *
  14 * You should have received a copy of the GNU General Public License along with
  15 * this program; if not, write to the Free Software Foundation, Inc.,
  16 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  17 *
  18 * Author: Eliezer Tamir
  19 *
  20 * Contact Information:
  21 * e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>
  22 */
  23
  24#ifndef _LINUX_NET_BUSY_POLL_H
  25#define _LINUX_NET_BUSY_POLL_H
  26
  27#include <linux/netdevice.h>
  28#include <linux/sched/clock.h>
  29#include <linux/sched/signal.h>
  30#include <net/ip.h>
  31
  32/*              0 - Reserved to indicate value not set
  33 *     1..NR_CPUS - Reserved for sender_cpu
  34 *  NR_CPUS+1..~0 - Region available for NAPI IDs
  35 */
  36#define MIN_NAPI_ID ((unsigned int)(NR_CPUS + 1))
  37
  38#ifdef CONFIG_NET_RX_BUSY_POLL
  39
  40struct napi_struct;
  41extern unsigned int sysctl_net_busy_read __read_mostly;
  42extern unsigned int sysctl_net_busy_poll __read_mostly;
  43
  44static inline bool net_busy_loop_on(void)
  45{
  46        return sysctl_net_busy_poll;
  47}
  48
  49static inline bool sk_can_busy_loop(const struct sock *sk)
  50{
  51        return sk->sk_ll_usec && !signal_pending(current);
  52}
  53
  54bool sk_busy_loop_end(void *p, unsigned long start_time);
  55
  56void napi_busy_loop(unsigned int napi_id,
  57                    bool (*loop_end)(void *, unsigned long),
  58                    void *loop_end_arg);
  59
  60#else /* CONFIG_NET_RX_BUSY_POLL */
  61static inline unsigned long net_busy_loop_on(void)
  62{
  63        return 0;
  64}
  65
  66static inline bool sk_can_busy_loop(struct sock *sk)
  67{
  68        return false;
  69}
  70
  71#endif /* CONFIG_NET_RX_BUSY_POLL */
  72
  73static inline unsigned long busy_loop_current_time(void)
  74{
  75#ifdef CONFIG_NET_RX_BUSY_POLL
  76        return (unsigned long)(local_clock() >> 10);
  77#else
  78        return 0;
  79#endif
  80}
  81
  82/* in poll/select we use the global sysctl_net_ll_poll value */
  83static inline bool busy_loop_timeout(unsigned long start_time)
  84{
  85#ifdef CONFIG_NET_RX_BUSY_POLL
  86        unsigned long bp_usec = READ_ONCE(sysctl_net_busy_poll);
  87
  88        if (bp_usec) {
  89                unsigned long end_time = start_time + bp_usec;
  90                unsigned long now = busy_loop_current_time();
  91
  92                return time_after(now, end_time);
  93        }
  94#endif
  95        return true;
  96}
  97
  98static inline bool sk_busy_loop_timeout(struct sock *sk,
  99                                        unsigned long start_time)
 100{
 101#ifdef CONFIG_NET_RX_BUSY_POLL
 102        unsigned long bp_usec = READ_ONCE(sk->sk_ll_usec);
 103
 104        if (bp_usec) {
 105                unsigned long end_time = start_time + bp_usec;
 106                unsigned long now = busy_loop_current_time();
 107
 108                return time_after(now, end_time);
 109        }
 110#endif
 111        return true;
 112}
 113
 114static inline void sk_busy_loop(struct sock *sk, int nonblock)
 115{
 116#ifdef CONFIG_NET_RX_BUSY_POLL
 117        unsigned int napi_id = READ_ONCE(sk->sk_napi_id);
 118
 119        if (napi_id >= MIN_NAPI_ID)
 120                napi_busy_loop(napi_id, nonblock ? NULL : sk_busy_loop_end, sk);
 121#endif
 122}
 123
 124/* used in the NIC receive handler to mark the skb */
 125static inline void skb_mark_napi_id(struct sk_buff *skb,
 126                                    struct napi_struct *napi)
 127{
 128#ifdef CONFIG_NET_RX_BUSY_POLL
 129        skb->napi_id = napi->napi_id;
 130#endif
 131}
 132
 133/* used in the protocol hanlder to propagate the napi_id to the socket */
 134static inline void sk_mark_napi_id(struct sock *sk, const struct sk_buff *skb)
 135{
 136#ifdef CONFIG_NET_RX_BUSY_POLL
 137        sk->sk_napi_id = skb->napi_id;
 138#endif
 139}
 140
 141/* variant used for unconnected sockets */
 142static inline void sk_mark_napi_id_once(struct sock *sk,
 143                                        const struct sk_buff *skb)
 144{
 145#ifdef CONFIG_NET_RX_BUSY_POLL
 146        if (!sk->sk_napi_id)
 147                sk->sk_napi_id = skb->napi_id;
 148#endif
 149}
 150
 151#endif /* _LINUX_NET_BUSY_POLL_H */
 152