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/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef _NET_RPS_H
#define _NET_RPS_H
#include <linux/types.h>
#include <linux/static_key.h>
#include <net/sock.h>
#include <net/hotdata.h>
#ifdef CONFIG_RPS
extern struct static_key_false rps_needed;
extern struct static_key_false rfs_needed;
/*
* This structure holds an RPS map which can be of variable length. The
* map is an array of CPUs.
*/
struct rps_map {
unsigned int len;
struct rcu_head rcu;
u16 cpus[];
};
#define RPS_MAP_SIZE(_num) (sizeof(struct rps_map) + ((_num) * sizeof(u16)))
/*
* The rps_dev_flow structure contains the mapping of a flow to a CPU, the
* tail pointer for that CPU's input queue at the time of last enqueue, and
* a hardware filter index.
*/
struct rps_dev_flow {
u16 cpu;
u16 filter;
unsigned int last_qtail;
};
#define RPS_NO_FILTER 0xffff
/*
* The rps_dev_flow_table structure contains a table of flow mappings.
*/
struct rps_dev_flow_table {
unsigned int mask;
struct rcu_head rcu;
struct rps_dev_flow flows[];
};
#define RPS_DEV_FLOW_TABLE_SIZE(_num) (sizeof(struct rps_dev_flow_table) + \
((_num) * sizeof(struct rps_dev_flow)))
/*
* The rps_sock_flow_table contains mappings of flows to the last CPU
* on which they were processed by the application (set in recvmsg).
* Each entry is a 32bit value. Upper part is the high-order bits
* of flow hash, lower part is CPU number.
* rps_cpu_mask is used to partition the space, depending on number of
* possible CPUs : rps_cpu_mask = roundup_pow_of_two(nr_cpu_ids) - 1
* For example, if 64 CPUs are possible, rps_cpu_mask = 0x3f,
* meaning we use 32-6=26 bits for the hash.
*/
struct rps_sock_flow_table {
u32 mask;
u32 ents[] ____cacheline_aligned_in_smp;
};
#define RPS_SOCK_FLOW_TABLE_SIZE(_num) (offsetof(struct rps_sock_flow_table, ents[_num]))
#define RPS_NO_CPU 0xffff
static inline void rps_record_sock_flow(struct rps_sock_flow_table *table,
u32 hash)
{
unsigned int index = hash & table->mask;
u32 val = hash & ~net_hotdata.rps_cpu_mask;
/* We only give a hint, preemption can change CPU under us */
val |= raw_smp_processor_id();
/* The following WRITE_ONCE() is paired with the READ_ONCE()
* here, and another one in get_rps_cpu().
*/
if (READ_ONCE(table->ents[index]) != val)
WRITE_ONCE(table->ents[index], val);
}
#endif /* CONFIG_RPS */
static inline void sock_rps_record_flow_hash(__u32 hash)
{
#ifdef CONFIG_RPS
struct rps_sock_flow_table *sock_flow_table;
if (!hash)
return;
rcu_read_lock();
sock_flow_table = rcu_dereference(net_hotdata.rps_sock_flow_table);
if (sock_flow_table)
rps_record_sock_flow(sock_flow_table, hash);
rcu_read_unlock();
#endif
}
static inline void sock_rps_record_flow(const struct sock *sk)
{
#ifdef CONFIG_RPS
if (static_branch_unlikely(&rfs_needed)) {
/* Reading sk->sk_rxhash might incur an expensive cache line
* miss.
*
* TCP_ESTABLISHED does cover almost all states where RFS
* might be useful, and is cheaper [1] than testing :
* IPv4: inet_sk(sk)->inet_daddr
* IPv6: ipv6_addr_any(&sk->sk_v6_daddr)
* OR an additional socket flag
* [1] : sk_state and sk_prot are in the same cache line.
*/
if (sk->sk_state == TCP_ESTABLISHED) {
/* This READ_ONCE() is paired with the WRITE_ONCE()
* from sock_rps_save_rxhash() and sock_rps_reset_rxhash().
*/
sock_rps_record_flow_hash(READ_ONCE(sk->sk_rxhash));
}
}
#endif
}
#endif /* _NET_RPS_H */
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