Linux kernel mirror (for testing)
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linux
1/* SPDX-License-Identifier: GPL-2.0-or-later */
2#ifndef _NET_RPS_H
3#define _NET_RPS_H
4
5#include <linux/types.h>
6#include <linux/static_key.h>
7#include <net/sock.h>
8#include <net/hotdata.h>
9
10#ifdef CONFIG_RPS
11
12extern struct static_key_false rps_needed;
13extern struct static_key_false rfs_needed;
14
15/*
16 * This structure holds an RPS map which can be of variable length. The
17 * map is an array of CPUs.
18 */
19struct rps_map {
20 unsigned int len;
21 struct rcu_head rcu;
22 u16 cpus[];
23};
24#define RPS_MAP_SIZE(_num) (sizeof(struct rps_map) + ((_num) * sizeof(u16)))
25
26/*
27 * The rps_dev_flow structure contains the mapping of a flow to a CPU, the
28 * tail pointer for that CPU's input queue at the time of last enqueue, a
29 * hardware filter index, and the hash of the flow if aRFS is enabled.
30 */
31struct rps_dev_flow {
32 u16 cpu;
33 u16 filter;
34 unsigned int last_qtail;
35#ifdef CONFIG_RFS_ACCEL
36 u32 hash;
37#endif
38};
39#define RPS_NO_FILTER 0xffff
40
41/*
42 * The rps_dev_flow_table structure contains a table of flow mappings.
43 */
44struct rps_dev_flow_table {
45 u8 log;
46 struct rcu_head rcu;
47 struct rps_dev_flow flows[];
48};
49#define RPS_DEV_FLOW_TABLE_SIZE(_num) (sizeof(struct rps_dev_flow_table) + \
50 ((_num) * sizeof(struct rps_dev_flow)))
51
52/*
53 * The rps_sock_flow_table contains mappings of flows to the last CPU
54 * on which they were processed by the application (set in recvmsg).
55 * Each entry is a 32bit value. Upper part is the high-order bits
56 * of flow hash, lower part is CPU number.
57 * rps_cpu_mask is used to partition the space, depending on number of
58 * possible CPUs : rps_cpu_mask = roundup_pow_of_two(nr_cpu_ids) - 1
59 * For example, if 64 CPUs are possible, rps_cpu_mask = 0x3f,
60 * meaning we use 32-6=26 bits for the hash.
61 */
62struct rps_sock_flow_table {
63 struct rcu_head rcu;
64 u32 mask;
65
66 u32 ents[] ____cacheline_aligned_in_smp;
67};
68#define RPS_SOCK_FLOW_TABLE_SIZE(_num) (offsetof(struct rps_sock_flow_table, ents[_num]))
69
70#define RPS_NO_CPU 0xffff
71
72static inline void rps_record_sock_flow(struct rps_sock_flow_table *table,
73 u32 hash)
74{
75 unsigned int index = hash & table->mask;
76 u32 val = hash & ~net_hotdata.rps_cpu_mask;
77
78 /* We only give a hint, preemption can change CPU under us */
79 val |= raw_smp_processor_id();
80
81 /* The following WRITE_ONCE() is paired with the READ_ONCE()
82 * here, and another one in get_rps_cpu().
83 */
84 if (READ_ONCE(table->ents[index]) != val)
85 WRITE_ONCE(table->ents[index], val);
86}
87
88static inline void _sock_rps_record_flow_hash(__u32 hash)
89{
90 struct rps_sock_flow_table *sock_flow_table;
91
92 if (!hash)
93 return;
94 rcu_read_lock();
95 sock_flow_table = rcu_dereference(net_hotdata.rps_sock_flow_table);
96 if (sock_flow_table)
97 rps_record_sock_flow(sock_flow_table, hash);
98 rcu_read_unlock();
99}
100
101static inline void _sock_rps_record_flow(const struct sock *sk)
102{
103 /* Reading sk->sk_rxhash might incur an expensive cache line
104 * miss.
105 *
106 * TCP_ESTABLISHED does cover almost all states where RFS
107 * might be useful, and is cheaper [1] than testing :
108 * IPv4: inet_sk(sk)->inet_daddr
109 * IPv6: ipv6_addr_any(&sk->sk_v6_daddr)
110 * OR an additional socket flag
111 * [1] : sk_state and sk_prot are in the same cache line.
112 */
113 if (sk->sk_state == TCP_ESTABLISHED) {
114 /* This READ_ONCE() is paired with the WRITE_ONCE()
115 * from sock_rps_save_rxhash() and sock_rps_reset_rxhash().
116 */
117 _sock_rps_record_flow_hash(READ_ONCE(sk->sk_rxhash));
118 }
119}
120
121static inline void _sock_rps_delete_flow(const struct sock *sk)
122{
123 struct rps_sock_flow_table *table;
124 u32 hash, index;
125
126 hash = READ_ONCE(sk->sk_rxhash);
127 if (!hash)
128 return;
129
130 rcu_read_lock();
131 table = rcu_dereference(net_hotdata.rps_sock_flow_table);
132 if (table) {
133 index = hash & table->mask;
134 if (READ_ONCE(table->ents[index]) != RPS_NO_CPU)
135 WRITE_ONCE(table->ents[index], RPS_NO_CPU);
136 }
137 rcu_read_unlock();
138}
139#endif /* CONFIG_RPS */
140
141static inline bool rfs_is_needed(void)
142{
143#ifdef CONFIG_RPS
144 return static_branch_unlikely(&rfs_needed);
145#else
146 return false;
147#endif
148}
149
150static inline void sock_rps_record_flow_hash(__u32 hash)
151{
152#ifdef CONFIG_RPS
153 if (!rfs_is_needed())
154 return;
155
156 _sock_rps_record_flow_hash(hash);
157#endif
158}
159
160static inline void sock_rps_record_flow(const struct sock *sk)
161{
162#ifdef CONFIG_RPS
163 if (!rfs_is_needed())
164 return;
165
166 _sock_rps_record_flow(sk);
167#endif
168}
169
170static inline void sock_rps_delete_flow(const struct sock *sk)
171{
172#ifdef CONFIG_RPS
173 if (!rfs_is_needed())
174 return;
175
176 _sock_rps_delete_flow(sk);
177#endif
178}
179
180static inline u32 rps_input_queue_tail_incr(struct softnet_data *sd)
181{
182#ifdef CONFIG_RPS
183 return ++sd->input_queue_tail;
184#else
185 return 0;
186#endif
187}
188
189static inline void rps_input_queue_tail_save(u32 *dest, u32 tail)
190{
191#ifdef CONFIG_RPS
192 WRITE_ONCE(*dest, tail);
193#endif
194}
195
196static inline void rps_input_queue_head_add(struct softnet_data *sd, int val)
197{
198#ifdef CONFIG_RPS
199 WRITE_ONCE(sd->input_queue_head, sd->input_queue_head + val);
200#endif
201}
202
203static inline void rps_input_queue_head_incr(struct softnet_data *sd)
204{
205 rps_input_queue_head_add(sd, 1);
206}
207
208#endif /* _NET_RPS_H */