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 12 extern struct static_key_false rps_needed; 13 extern 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 */ 19 struct 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, and 29 * a hardware filter index. 30 */ 31 struct rps_dev_flow { 32 u16 cpu; 33 u16 filter; 34 unsigned int last_qtail; 35 }; 36 #define RPS_NO_FILTER 0xffff 37 38 /* 39 * The rps_dev_flow_table structure contains a table of flow mappings. 40 */ 41 struct rps_dev_flow_table { 42 u8 log; 43 struct rcu_head rcu; 44 struct rps_dev_flow flows[]; 45 }; 46 #define RPS_DEV_FLOW_TABLE_SIZE(_num) (sizeof(struct rps_dev_flow_table) + \ 47 ((_num) * sizeof(struct rps_dev_flow))) 48 49 /* 50 * The rps_sock_flow_table contains mappings of flows to the last CPU 51 * on which they were processed by the application (set in recvmsg). 52 * Each entry is a 32bit value. Upper part is the high-order bits 53 * of flow hash, lower part is CPU number. 54 * rps_cpu_mask is used to partition the space, depending on number of 55 * possible CPUs : rps_cpu_mask = roundup_pow_of_two(nr_cpu_ids) - 1 56 * For example, if 64 CPUs are possible, rps_cpu_mask = 0x3f, 57 * meaning we use 32-6=26 bits for the hash. 58 */ 59 struct rps_sock_flow_table { 60 struct rcu_head rcu; 61 u32 mask; 62 63 u32 ents[] ____cacheline_aligned_in_smp; 64 }; 65 #define RPS_SOCK_FLOW_TABLE_SIZE(_num) (offsetof(struct rps_sock_flow_table, ents[_num])) 66 67 #define RPS_NO_CPU 0xffff 68 69 static inline void rps_record_sock_flow(struct rps_sock_flow_table *table, 70 u32 hash) 71 { 72 unsigned int index = hash & table->mask; 73 u32 val = hash & ~net_hotdata.rps_cpu_mask; 74 75 /* We only give a hint, preemption can change CPU under us */ 76 val |= raw_smp_processor_id(); 77 78 /* The following WRITE_ONCE() is paired with the READ_ONCE() 79 * here, and another one in get_rps_cpu(). 80 */ 81 if (READ_ONCE(table->ents[index]) != val) 82 WRITE_ONCE(table->ents[index], val); 83 } 84 85 #endif /* CONFIG_RPS */ 86 87 static inline void sock_rps_record_flow_hash(__u32 hash) 88 { 89 #ifdef CONFIG_RPS 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 #endif 100 } 101 102 static inline void sock_rps_record_flow(const struct sock *sk) 103 { 104 #ifdef CONFIG_RPS 105 if (static_branch_unlikely(&rfs_needed)) { 106 /* Reading sk->sk_rxhash might incur an expensive cache line 107 * miss. 108 * 109 * TCP_ESTABLISHED does cover almost all states where RFS 110 * might be useful, and is cheaper [1] than testing : 111 * IPv4: inet_sk(sk)->inet_daddr 112 * IPv6: ipv6_addr_any(&sk->sk_v6_daddr) 113 * OR an additional socket flag 114 * [1] : sk_state and sk_prot are in the same cache line. 115 */ 116 if (sk->sk_state == TCP_ESTABLISHED) { 117 /* This READ_ONCE() is paired with the WRITE_ONCE() 118 * from sock_rps_save_rxhash() and sock_rps_reset_rxhash(). 119 */ 120 sock_rps_record_flow_hash(READ_ONCE(sk->sk_rxhash)); 121 } 122 } 123 #endif 124 } 125 126 static inline void sock_rps_delete_flow(const struct sock *sk) 127 { 128 #ifdef CONFIG_RPS 129 struct rps_sock_flow_table *table; 130 u32 hash, index; 131 132 if (!static_branch_unlikely(&rfs_needed)) 133 return; 134 135 hash = READ_ONCE(sk->sk_rxhash); 136 if (!hash) 137 return; 138 139 rcu_read_lock(); 140 table = rcu_dereference(net_hotdata.rps_sock_flow_table); 141 if (table) { 142 index = hash & table->mask; 143 if (READ_ONCE(table->ents[index]) != RPS_NO_CPU) 144 WRITE_ONCE(table->ents[index], RPS_NO_CPU); 145 } 146 rcu_read_unlock(); 147 #endif 148 } 149 150 static inline u32 rps_input_queue_tail_incr(struct softnet_data *sd) 151 { 152 #ifdef CONFIG_RPS 153 return ++sd->input_queue_tail; 154 #else 155 return 0; 156 #endif 157 } 158 159 static inline void rps_input_queue_tail_save(u32 *dest, u32 tail) 160 { 161 #ifdef CONFIG_RPS 162 WRITE_ONCE(*dest, tail); 163 #endif 164 } 165 166 static inline void rps_input_queue_head_add(struct softnet_data *sd, int val) 167 { 168 #ifdef CONFIG_RPS 169 WRITE_ONCE(sd->input_queue_head, sd->input_queue_head + val); 170 #endif 171 } 172 173 static inline void rps_input_queue_head_incr(struct softnet_data *sd) 174 { 175 rps_input_queue_head_add(sd, 1); 176 } 177 178 #endif /* _NET_RPS_H */ 179