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Eliezer Tamir06021292013-06-10 11:39:50 +03001/*
Eliezer Tamir8b80cda2013-07-10 17:13:26 +03002 * net busy poll support
Eliezer Tamir06021292013-06-10 11:39:50 +03003 * 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
Eliezer Tamir8b80cda2013-07-10 17:13:26 +030024#ifndef _LINUX_NET_BUSY_POLL_H
25#define _LINUX_NET_BUSY_POLL_H
Eliezer Tamir06021292013-06-10 11:39:50 +030026
27#include <linux/netdevice.h>
28#include <net/ip.h>
29
30#ifdef CONFIG_NET_LL_RX_POLL
31
32struct napi_struct;
Eliezer Tamir64b0dc52013-07-10 17:13:36 +030033extern unsigned int sysctl_net_busy_read __read_mostly;
34extern unsigned int sysctl_net_busy_poll __read_mostly;
Eliezer Tamir06021292013-06-10 11:39:50 +030035
36/* return values from ndo_ll_poll */
37#define LL_FLUSH_FAILED -1
38#define LL_FLUSH_BUSY -2
39
Eliezer Tamircbf55002013-07-08 16:20:34 +030040static inline bool net_busy_loop_on(void)
Eliezer Tamir91e2fd332013-06-28 15:59:35 +030041{
Eliezer Tamir64b0dc52013-07-10 17:13:36 +030042 return sysctl_net_busy_poll;
Eliezer Tamir91e2fd332013-06-28 15:59:35 +030043}
44
Eliezer Tamirad6276e2013-06-28 15:59:26 +030045/* a wrapper to make debug_smp_processor_id() happy
46 * we can use sched_clock() because we don't care much about precision
Eliezer Tamir9a3c71a2013-06-14 16:33:35 +030047 * we only care that the average is bounded
Eliezer Tamirad6276e2013-06-28 15:59:26 +030048 */
49#ifdef CONFIG_DEBUG_PREEMPT
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +030050static inline u64 busy_loop_us_clock(void)
Eliezer Tamirad6276e2013-06-28 15:59:26 +030051{
52 u64 rc;
53
54 preempt_disable_notrace();
55 rc = sched_clock();
56 preempt_enable_no_resched_notrace();
57
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +030058 return rc >> 10;
Eliezer Tamirad6276e2013-06-28 15:59:26 +030059}
60#else /* CONFIG_DEBUG_PREEMPT */
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +030061static inline u64 busy_loop_us_clock(void)
Eliezer Tamirad6276e2013-06-28 15:59:26 +030062{
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +030063 return sched_clock() >> 10;
Eliezer Tamirad6276e2013-06-28 15:59:26 +030064}
65#endif /* CONFIG_DEBUG_PREEMPT */
66
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +030067static inline unsigned long sk_busy_loop_end_time(struct sock *sk)
Eliezer Tamir06021292013-06-10 11:39:50 +030068{
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +030069 return busy_loop_us_clock() + ACCESS_ONCE(sk->sk_ll_usec);
Eliezer Tamir2d48d672013-06-24 10:28:03 +030070}
Eliezer Tamir9a3c71a2013-06-14 16:33:35 +030071
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +030072/* in poll/select we use the global sysctl_net_ll_poll value */
73static inline unsigned long busy_loop_end_time(void)
Eliezer Tamir2d48d672013-06-24 10:28:03 +030074{
Eliezer Tamir64b0dc52013-07-10 17:13:36 +030075 return busy_loop_us_clock() + ACCESS_ONCE(sysctl_net_busy_poll);
Eliezer Tamir06021292013-06-10 11:39:50 +030076}
77
Eliezer Tamircbf55002013-07-08 16:20:34 +030078static inline bool sk_can_busy_loop(struct sock *sk)
Eliezer Tamir06021292013-06-10 11:39:50 +030079{
Eliezer Tamirdafcc432013-06-14 16:33:57 +030080 return sk->sk_ll_usec && sk->sk_napi_id &&
Eliezer Tamir06021292013-06-10 11:39:50 +030081 !need_resched() && !signal_pending(current);
82}
83
Eliezer Tamir1bc27742013-07-02 23:22:47 +030084
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +030085static inline bool busy_loop_timeout(unsigned long end_time)
86{
87 unsigned long now = busy_loop_us_clock();
88
89 return time_after(now, end_time);
Eliezer Tamir06021292013-06-10 11:39:50 +030090}
91
Eliezer Tamir2d48d672013-06-24 10:28:03 +030092/* when used in sock_poll() nonblock is known at compile time to be true
93 * so the loop and end_time will be optimized out
94 */
Eliezer Tamircbf55002013-07-08 16:20:34 +030095static inline bool sk_busy_loop(struct sock *sk, int nonblock)
Eliezer Tamir06021292013-06-10 11:39:50 +030096{
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +030097 unsigned long end_time = !nonblock ? sk_busy_loop_end_time(sk) : 0;
Eliezer Tamir06021292013-06-10 11:39:50 +030098 const struct net_device_ops *ops;
99 struct napi_struct *napi;
100 int rc = false;
101
102 /*
103 * rcu read lock for napi hash
104 * bh so we don't race with net_rx_action
105 */
106 rcu_read_lock_bh();
107
108 napi = napi_by_id(sk->sk_napi_id);
109 if (!napi)
110 goto out;
111
112 ops = napi->dev->netdev_ops;
Eliezer Tamir8b80cda2013-07-10 17:13:26 +0300113 if (!ops->ndo_busy_poll)
Eliezer Tamir06021292013-06-10 11:39:50 +0300114 goto out;
115
116 do {
Eliezer Tamir8b80cda2013-07-10 17:13:26 +0300117 rc = ops->ndo_busy_poll(napi);
Eliezer Tamir06021292013-06-10 11:39:50 +0300118
119 if (rc == LL_FLUSH_FAILED)
120 break; /* permanent failure */
121
122 if (rc > 0)
123 /* local bh are disabled so it is ok to use _BH */
124 NET_ADD_STATS_BH(sock_net(sk),
125 LINUX_MIB_LOWLATENCYRXPACKETS, rc);
126
Eliezer Tamir2d48d672013-06-24 10:28:03 +0300127 } while (!nonblock && skb_queue_empty(&sk->sk_receive_queue) &&
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +0300128 !need_resched() && !busy_loop_timeout(end_time));
Eliezer Tamir06021292013-06-10 11:39:50 +0300129
130 rc = !skb_queue_empty(&sk->sk_receive_queue);
131out:
132 rcu_read_unlock_bh();
133 return rc;
134}
135
136/* used in the NIC receive handler to mark the skb */
Eliezer Tamir8b80cda2013-07-10 17:13:26 +0300137static inline void skb_mark_napi_id(struct sk_buff *skb,
138 struct napi_struct *napi)
Eliezer Tamir06021292013-06-10 11:39:50 +0300139{
140 skb->napi_id = napi->napi_id;
141}
142
143/* used in the protocol hanlder to propagate the napi_id to the socket */
Eliezer Tamir8b80cda2013-07-10 17:13:26 +0300144static inline void sk_mark_napi_id(struct sock *sk, struct sk_buff *skb)
Eliezer Tamir06021292013-06-10 11:39:50 +0300145{
146 sk->sk_napi_id = skb->napi_id;
147}
148
149#else /* CONFIG_NET_LL_RX_POLL */
Eliezer Tamircbf55002013-07-08 16:20:34 +0300150static inline unsigned long net_busy_loop_on(void)
Eliezer Tamir91e2fd332013-06-28 15:59:35 +0300151{
152 return 0;
153}
Eliezer Tamir06021292013-06-10 11:39:50 +0300154
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +0300155static inline unsigned long busy_loop_end_time(void)
Eliezer Tamir06021292013-06-10 11:39:50 +0300156{
157 return 0;
158}
159
Eliezer Tamircbf55002013-07-08 16:20:34 +0300160static inline bool sk_can_busy_loop(struct sock *sk)
Eliezer Tamir06021292013-06-10 11:39:50 +0300161{
162 return false;
163}
164
Eliezer Tamircbf55002013-07-08 16:20:34 +0300165static inline bool sk_busy_poll(struct sock *sk, int nonblock)
Eliezer Tamir06021292013-06-10 11:39:50 +0300166{
167 return false;
168}
169
Eliezer Tamir8b80cda2013-07-10 17:13:26 +0300170static inline void skb_mark_napi_id(struct sk_buff *skb,
171 struct napi_struct *napi)
Eliezer Tamir06021292013-06-10 11:39:50 +0300172{
173}
174
Eliezer Tamir8b80cda2013-07-10 17:13:26 +0300175static inline void sk_mark_napi_id(struct sock *sk, struct sk_buff *skb)
Eliezer Tamir06021292013-06-10 11:39:50 +0300176{
177}
178
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +0300179static inline bool busy_loop_timeout(unsigned long end_time)
Eliezer Tamir06021292013-06-10 11:39:50 +0300180{
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +0300181 return true;
Eliezer Tamir06021292013-06-10 11:39:50 +0300182}
183
184#endif /* CONFIG_NET_LL_RX_POLL */
Eliezer Tamir8b80cda2013-07-10 17:13:26 +0300185#endif /* _LINUX_NET_BUSY_POLL_H */