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 <net/ip.h>
 29
 30#ifdef CONFIG_NET_RX_BUSY_POLL
 31
 32struct napi_struct;
 33extern unsigned int sysctl_net_busy_read __read_mostly;
 34extern unsigned int sysctl_net_busy_poll __read_mostly;
 35
 36/* return values from ndo_ll_poll */
 37#define LL_FLUSH_FAILED		-1
 38#define LL_FLUSH_BUSY		-2
 39
 40static inline bool net_busy_loop_on(void)
 41{
 42	return sysctl_net_busy_poll;
 43}
 44
 45static inline u64 busy_loop_us_clock(void)
 46{
 47	return local_clock() >> 10;
 48}
 49
 50static inline unsigned long sk_busy_loop_end_time(struct sock *sk)
 51{
 52	return busy_loop_us_clock() + ACCESS_ONCE(sk->sk_ll_usec);
 53}
 54
 55/* in poll/select we use the global sysctl_net_ll_poll value */
 56static inline unsigned long busy_loop_end_time(void)
 57{
 58	return busy_loop_us_clock() + ACCESS_ONCE(sysctl_net_busy_poll);
 59}
 60
 61static inline bool sk_can_busy_loop(struct sock *sk)
 62{
 63	return sk->sk_ll_usec && sk->sk_napi_id &&
 64	       !need_resched() && !signal_pending(current);
 65}
 66
 67
 68static inline bool busy_loop_timeout(unsigned long end_time)
 69{
 70	unsigned long now = busy_loop_us_clock();
 71
 72	return time_after(now, end_time);
 73}
 74
 75bool sk_busy_loop(struct sock *sk, int nonblock);
 76
 77/* used in the NIC receive handler to mark the skb */
 78static inline void skb_mark_napi_id(struct sk_buff *skb,
 79				    struct napi_struct *napi)
 80{
 81	skb->napi_id = napi->napi_id;
 82}
 83
 84/* used in the protocol hanlder to propagate the napi_id to the socket */
 85static inline void sk_mark_napi_id(struct sock *sk, struct sk_buff *skb)
 86{
 87	sk->sk_napi_id = skb->napi_id;
 88}
 89
 90#else /* CONFIG_NET_RX_BUSY_POLL */
 91static inline unsigned long net_busy_loop_on(void)
 92{
 93	return 0;
 94}
 95
 96static inline unsigned long busy_loop_end_time(void)
 97{
 98	return 0;
 99}
100
101static inline bool sk_can_busy_loop(struct sock *sk)
102{
103	return false;
104}
105
106static inline void skb_mark_napi_id(struct sk_buff *skb,
107				    struct napi_struct *napi)
108{
109}
110
111static inline void sk_mark_napi_id(struct sock *sk, struct sk_buff *skb)
112{
113}
114
115static inline bool busy_loop_timeout(unsigned long end_time)
116{
117	return true;
118}
119
120static inline bool sk_busy_loop(struct sock *sk, int nonblock)
121{
122	return false;
123}
124
125#endif /* CONFIG_NET_RX_BUSY_POLL */
126#endif /* _LINUX_NET_BUSY_POLL_H */