From 9cc63f8bcd560c760d0b12e15bba8f81c86237cf Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 14 Aug 2026 15:43:51 -0700 Subject: Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEAD Changes: Make expedited grace periods expedite normal RCU callbacks Miscellaneous fixes: * Improve diagnostic output with character task states. * Mark accesses to inform KCSAN of concurrency design. * Move from kmalloc() to kmalloc_obj(). * Documentation updates. * Improve handling of RCU deferred quiescent states. * Clean up unused function arguments and structure fields. * Reduce show_rcu_gp_kthreads() stack space. Tasks RCU updates: * Clean up after SRCU re-implementation of Tasks Trace RCU. * Mark accesses to inform KCSAN of concurrency design. * Add ->lazy_timer status to diagnostic output. * Remove an unnecessary memory barrier. * Fix a data race, courtesy of KCSAN. * Documentation updates. * Convert cond_resched_tasks_rcu_qs() from macro to static inline function. SRCU updates: * Add Rust helpers for SRCU. * Avoid losing queued work at cleanup_srcu_struct() time. Torture-test updates: * Preparation work for immediate RCU priority deboosting. * Test RCU readers from real interrupt handlers (as opposed to softirq). * Simplify code through use of cpumask_next_wrap(). * Improve diagnostic output with character task states. * Add rcutorture.nwriters parameter to allow lightweight stall testing, and rcutorture.stall_only to make doing so easier. * Test an RCU Tasks Trace grace period implying an RCU grace period. * Make RCU Tasks Trace torturing track reader batches. * Fix a data race, courtesy of KCSAN. * Plug a shuffle_tmp_mask memory leak on kthread spawn failure. --- include/net/rps.h | 197 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 197 insertions(+) create mode 100644 include/net/rps.h (limited to 'include/net/rps.h') diff --git a/include/net/rps.h b/include/net/rps.h new file mode 100644 index 000000000..e33c6a2fa --- /dev/null +++ b/include/net/rps.h @@ -0,0 +1,197 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +#ifndef _NET_RPS_H +#define _NET_RPS_H + +#include +#include +#include +#include + +#ifdef CONFIG_RPS +#include + +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, a + * hardware filter index, and the hash of the flow if aRFS is enabled. + */ +struct rps_dev_flow { + u16 cpu; + u16 filter; + unsigned int last_qtail; +#ifdef CONFIG_RFS_ACCEL + u32 hash; +#endif +}; +#define RPS_NO_FILTER 0xffff + +/* + * 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 ent; +}; + +#define RPS_NO_CPU 0xffff + +static inline void rps_record_sock_flow(rps_tag_ptr tag_ptr, u32 hash) +{ + unsigned int index = hash & rps_tag_to_mask(tag_ptr); + u32 val = hash & ~net_hotdata.rps_cpu_mask; + struct rps_sock_flow_table *table; + + /* We only give a hint, preemption can change CPU under us */ + val |= raw_smp_processor_id(); + + table = rps_tag_to_table(tag_ptr); + /* The following WRITE_ONCE() is paired with the READ_ONCE() + * here, and another one in get_rps_cpu(). + */ + if (READ_ONCE(table[index].ent) != val) + WRITE_ONCE(table[index].ent, val); +} + +static inline void _sock_rps_record_flow_hash(__u32 hash) +{ + rps_tag_ptr tag_ptr; + + if (!hash) + return; + rcu_read_lock(); + tag_ptr = READ_ONCE(net_hotdata.rps_sock_flow_table); + if (tag_ptr) + rps_record_sock_flow(tag_ptr, hash); + rcu_read_unlock(); +} + +static inline void _sock_rps_record_flow(const struct sock *sk) +{ + /* 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)); + } +} + +static inline void _sock_rps_delete_flow(const struct sock *sk) +{ + struct rps_sock_flow_table *table; + rps_tag_ptr tag_ptr; + u32 hash, index; + + hash = READ_ONCE(sk->sk_rxhash); + if (!hash) + return; + + rcu_read_lock(); + tag_ptr = READ_ONCE(net_hotdata.rps_sock_flow_table); + if (tag_ptr) { + index = hash & rps_tag_to_mask(tag_ptr); + table = rps_tag_to_table(tag_ptr); + if (READ_ONCE(table[index].ent) != RPS_NO_CPU) + WRITE_ONCE(table[index].ent, RPS_NO_CPU); + } + rcu_read_unlock(); +} +#endif /* CONFIG_RPS */ + +static inline bool rfs_is_needed(void) +{ +#ifdef CONFIG_RPS + return static_branch_unlikely(&rfs_needed); +#else + return false; +#endif +} + +static inline void sock_rps_record_flow_hash(__u32 hash) +{ +#ifdef CONFIG_RPS + if (!rfs_is_needed()) + return; + + _sock_rps_record_flow_hash(hash); +#endif +} + +static inline void sock_rps_record_flow(const struct sock *sk) +{ +#ifdef CONFIG_RPS + if (!rfs_is_needed()) + return; + + _sock_rps_record_flow(sk); +#endif +} + +static inline void sock_rps_delete_flow(const struct sock *sk) +{ +#ifdef CONFIG_RPS + if (!rfs_is_needed()) + return; + + _sock_rps_delete_flow(sk); +#endif +} + +static inline u32 rps_input_queue_tail_incr(struct softnet_data *sd) +{ +#ifdef CONFIG_RPS + return ++sd->input_queue_tail; +#else + return 0; +#endif +} + +static inline void rps_input_queue_tail_save(u32 *dest, u32 tail) +{ +#ifdef CONFIG_RPS + WRITE_ONCE(*dest, tail); +#endif +} + +static inline void rps_input_queue_head_add(struct softnet_data *sd, int val) +{ +#ifdef CONFIG_RPS + WRITE_ONCE(sd->input_queue_head, sd->input_queue_head + val); +#endif +} + +static inline void rps_input_queue_head_incr(struct softnet_data *sd) +{ + rps_input_queue_head_add(sd, 1); +} + +#endif /* _NET_RPS_H */ -- cgit v1.3.1