tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
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
45/* a wrapper to make debug_smp_processor_id() happy
46 * we can use sched_clock() because we don't care much about precision
47 * we only care that the average is bounded
48 */
49#ifdef CONFIG_DEBUG_PREEMPT
50static inline u64 busy_loop_us_clock(void)
51{
52 u64 rc;
53
54 preempt_disable_notrace();
55 rc = sched_clock();
56 preempt_enable_no_resched_notrace();
57
58 return rc >> 10;
59}
60#else /* CONFIG_DEBUG_PREEMPT */
61static inline u64 busy_loop_us_clock(void)
62{
63 return sched_clock() >> 10;
64}
65#endif /* CONFIG_DEBUG_PREEMPT */
66
67static inline unsigned long sk_busy_loop_end_time(struct sock *sk)
68{
69 return busy_loop_us_clock() + ACCESS_ONCE(sk->sk_ll_usec);
70}
71
72/* in poll/select we use the global sysctl_net_ll_poll value */
73static inline unsigned long busy_loop_end_time(void)
74{
75 return busy_loop_us_clock() + ACCESS_ONCE(sysctl_net_busy_poll);
76}
77
78static inline bool sk_can_busy_loop(struct sock *sk)
79{
80 return sk->sk_ll_usec && sk->sk_napi_id &&
81 !need_resched() && !signal_pending(current);
82}
83
84
85static 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);
90}
91
92/* 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 */
95static inline bool sk_busy_loop(struct sock *sk, int nonblock)
96{
97 unsigned long end_time = !nonblock ? sk_busy_loop_end_time(sk) : 0;
98 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;
113 if (!ops->ndo_busy_poll)
114 goto out;
115
116 do {
117 rc = ops->ndo_busy_poll(napi);
118
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_BUSYPOLLRXPACKETS, rc);
126 cpu_relax();
127
128 } while (!nonblock && skb_queue_empty(&sk->sk_receive_queue) &&
129 !need_resched() && !busy_loop_timeout(end_time));
130
131 rc = !skb_queue_empty(&sk->sk_receive_queue);
132out:
133 rcu_read_unlock_bh();
134 return rc;
135}
136
137/* used in the NIC receive handler to mark the skb */
138static inline void skb_mark_napi_id(struct sk_buff *skb,
139 struct napi_struct *napi)
140{
141 skb->napi_id = napi->napi_id;
142}
143
144/* used in the protocol hanlder to propagate the napi_id to the socket */
145static inline void sk_mark_napi_id(struct sock *sk, struct sk_buff *skb)
146{
147 sk->sk_napi_id = skb->napi_id;
148}
149
150#else /* CONFIG_NET_RX_BUSY_POLL */
151static inline unsigned long net_busy_loop_on(void)
152{
153 return 0;
154}
155
156static inline unsigned long busy_loop_end_time(void)
157{
158 return 0;
159}
160
161static inline bool sk_can_busy_loop(struct sock *sk)
162{
163 return false;
164}
165
166static inline void skb_mark_napi_id(struct sk_buff *skb,
167 struct napi_struct *napi)
168{
169}
170
171static inline void sk_mark_napi_id(struct sock *sk, struct sk_buff *skb)
172{
173}
174
175static inline bool busy_loop_timeout(unsigned long end_time)
176{
177 return true;
178}
179
180static inline bool sk_busy_loop(struct sock *sk, int nonblock)
181{
182 return false;
183}
184
185#endif /* CONFIG_NET_RX_BUSY_POLL */
186#endif /* _LINUX_NET_BUSY_POLL_H */