1 /* SPDX-License-Identifier: GPL-2.0+ */ 2 /* 3 * Sleepable Read-Copy Update mechanism for mutual exclusion, 4 * tree variant. 5 * 6 * Copyright (C) IBM Corporation, 2017 7 * 8 * Author: Paul McKenney <paulmck@linux.ibm.com> 9 */ 10 11 #ifndef _LINUX_SRCU_TREE_H 12 #define _LINUX_SRCU_TREE_H 13 14 #include <linux/rcu_node_tree.h> 15 #include <linux/completion.h> 16 17 struct srcu_node; 18 struct srcu_struct; 19 20 /* 21 * Per-CPU structure feeding into leaf srcu_node, similar in function 22 * to rcu_node. 23 */ 24 struct srcu_data { 25 /* Read-side state. */ 26 unsigned long srcu_lock_count[2]; /* Locks per CPU. */ 27 unsigned long srcu_unlock_count[2]; /* Unlocks per CPU. */ 28 29 /* Update-side state. */ 30 spinlock_t __private lock ____cacheline_internodealigned_in_smp; 31 struct rcu_segcblist srcu_cblist; /* List of callbacks.*/ 32 unsigned long srcu_gp_seq_needed; /* Furthest future GP needed. */ 33 unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */ 34 bool srcu_cblist_invoking; /* Invoking these CBs? */ 35 struct timer_list delay_work; /* Delay for CB invoking */ 36 struct work_struct work; /* Context for CB invoking. */ 37 struct rcu_head srcu_barrier_head; /* For srcu_barrier() use. */ 38 struct srcu_node *mynode; /* Leaf srcu_node. */ 39 unsigned long grpmask; /* Mask for leaf srcu_node */ 40 /* ->srcu_data_have_cbs[]. */ 41 int cpu; 42 struct srcu_struct *ssp; 43 }; 44 45 /* 46 * Node in SRCU combining tree, similar in function to rcu_data. 47 */ 48 struct srcu_node { 49 spinlock_t __private lock; 50 unsigned long srcu_have_cbs[4]; /* GP seq for children */ 51 /* having CBs, but only */ 52 /* is > ->srcu_gq_seq. */ 53 unsigned long srcu_data_have_cbs[4]; /* Which srcu_data structs */ 54 /* have CBs for given GP? */ 55 unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */ 56 struct srcu_node *srcu_parent; /* Next up in tree. */ 57 int grplo; /* Least CPU for node. */ 58 int grphi; /* Biggest CPU for node. */ 59 }; 60 61 /* 62 * Per-SRCU-domain structure, similar in function to rcu_state. 63 */ 64 struct srcu_struct { 65 struct srcu_node node[NUM_RCU_NODES]; /* Combining tree. */ 66 struct srcu_node *level[RCU_NUM_LVLS + 1]; 67 /* First node at each level. */ 68 struct mutex srcu_cb_mutex; /* Serialize CB preparation. */ 69 spinlock_t __private lock; /* Protect counters */ 70 struct mutex srcu_gp_mutex; /* Serialize GP work. */ 71 unsigned int srcu_idx; /* Current rdr array element. */ 72 unsigned long srcu_gp_seq; /* Grace-period seq #. */ 73 unsigned long srcu_gp_seq_needed; /* Latest gp_seq needed. */ 74 unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */ 75 unsigned long srcu_last_gp_end; /* Last GP end timestamp (ns) */ 76 struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ 77 unsigned long srcu_barrier_seq; /* srcu_barrier seq #. */ 78 struct mutex srcu_barrier_mutex; /* Serialize barrier ops. */ 79 struct completion srcu_barrier_completion; 80 /* Awaken barrier rq at end. */ 81 atomic_t srcu_barrier_cpu_cnt; /* # CPUs not yet posting a */ 82 /* callback for the barrier */ 83 /* operation. */ 84 struct delayed_work work; 85 struct lockdep_map dep_map; 86 }; 87 88 /* Values for state variable (bottom bits of ->srcu_gp_seq). */ 89 #define SRCU_STATE_IDLE 0 90 #define SRCU_STATE_SCAN1 1 91 #define SRCU_STATE_SCAN2 2 92 93 #define __SRCU_STRUCT_INIT(name, pcpu_name) \ 94 { \ 95 .sda = &pcpu_name, \ 96 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ 97 .srcu_gp_seq_needed = -1UL, \ 98 .work = __DELAYED_WORK_INITIALIZER(name.work, NULL, 0), \ 99 __SRCU_DEP_MAP_INIT(name) \ 100 } 101 102 /* 103 * Define and initialize a srcu struct at build time. 104 * Do -not- call init_srcu_struct() nor cleanup_srcu_struct() on it. 105 * 106 * Note that although DEFINE_STATIC_SRCU() hides the name from other 107 * files, the per-CPU variable rules nevertheless require that the 108 * chosen name be globally unique. These rules also prohibit use of 109 * DEFINE_STATIC_SRCU() within a function. If these rules are too 110 * restrictive, declare the srcu_struct manually. For example, in 111 * each file: 112 * 113 * static struct srcu_struct my_srcu; 114 * 115 * Then, before the first use of each my_srcu, manually initialize it: 116 * 117 * init_srcu_struct(&my_srcu); 118 * 119 * See include/linux/percpu-defs.h for the rules on per-CPU variables. 120 */ 121 #ifdef MODULE 122 # define __DEFINE_SRCU(name, is_static) \ 123 is_static struct srcu_struct name; \ 124 struct srcu_struct * const __srcu_struct_##name \ 125 __section("___srcu_struct_ptrs") = &name 126 #else 127 # define __DEFINE_SRCU(name, is_static) \ 128 static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data); \ 129 is_static struct srcu_struct name = \ 130 __SRCU_STRUCT_INIT(name, name##_srcu_data) 131 #endif 132 #define DEFINE_SRCU(name) __DEFINE_SRCU(name, /* not static */) 133 #define DEFINE_STATIC_SRCU(name) __DEFINE_SRCU(name, static) 134 135 void synchronize_srcu_expedited(struct srcu_struct *ssp); 136 void srcu_barrier(struct srcu_struct *ssp); 137 void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf); 138 139 #endif 140