1 /* 2 * Sleepable Read-Copy Update mechanism for mutual exclusion, 3 * tree variant. 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation; either version 2 of the License, or 8 * (at your option) any later version. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program; if not, you can access it online at 17 * http://www.gnu.org/licenses/gpl-2.0.html. 18 * 19 * Copyright (C) IBM Corporation, 2017 20 * 21 * Author: Paul McKenney <paulmck@us.ibm.com> 22 */ 23 24 #ifndef _LINUX_SRCU_TREE_H 25 #define _LINUX_SRCU_TREE_H 26 27 #include <linux/rcu_node_tree.h> 28 #include <linux/completion.h> 29 30 struct srcu_node; 31 struct srcu_struct; 32 33 /* 34 * Per-CPU structure feeding into leaf srcu_node, similar in function 35 * to rcu_node. 36 */ 37 struct srcu_data { 38 /* Read-side state. */ 39 unsigned long srcu_lock_count[2]; /* Locks per CPU. */ 40 unsigned long srcu_unlock_count[2]; /* Unlocks per CPU. */ 41 42 /* Update-side state. */ 43 spinlock_t __private lock ____cacheline_internodealigned_in_smp; 44 struct rcu_segcblist srcu_cblist; /* List of callbacks.*/ 45 unsigned long srcu_gp_seq_needed; /* Furthest future GP needed. */ 46 unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */ 47 bool srcu_cblist_invoking; /* Invoking these CBs? */ 48 struct delayed_work work; /* Context for CB invoking. */ 49 struct rcu_head srcu_barrier_head; /* For srcu_barrier() use. */ 50 struct srcu_node *mynode; /* Leaf srcu_node. */ 51 unsigned long grpmask; /* Mask for leaf srcu_node */ 52 /* ->srcu_data_have_cbs[]. */ 53 int cpu; 54 struct srcu_struct *sp; 55 }; 56 57 /* 58 * Node in SRCU combining tree, similar in function to rcu_data. 59 */ 60 struct srcu_node { 61 spinlock_t __private lock; 62 unsigned long srcu_have_cbs[4]; /* GP seq for children */ 63 /* having CBs, but only */ 64 /* is > ->srcu_gq_seq. */ 65 unsigned long srcu_data_have_cbs[4]; /* Which srcu_data structs */ 66 /* have CBs for given GP? */ 67 unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */ 68 struct srcu_node *srcu_parent; /* Next up in tree. */ 69 int grplo; /* Least CPU for node. */ 70 int grphi; /* Biggest CPU for node. */ 71 }; 72 73 /* 74 * Per-SRCU-domain structure, similar in function to rcu_state. 75 */ 76 struct srcu_struct { 77 struct srcu_node node[NUM_RCU_NODES]; /* Combining tree. */ 78 struct srcu_node *level[RCU_NUM_LVLS + 1]; 79 /* First node at each level. */ 80 struct mutex srcu_cb_mutex; /* Serialize CB preparation. */ 81 spinlock_t __private lock; /* Protect counters */ 82 struct mutex srcu_gp_mutex; /* Serialize GP work. */ 83 unsigned int srcu_idx; /* Current rdr array element. */ 84 unsigned long srcu_gp_seq; /* Grace-period seq #. */ 85 unsigned long srcu_gp_seq_needed; /* Latest gp_seq needed. */ 86 unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */ 87 unsigned long srcu_last_gp_end; /* Last GP end timestamp (ns) */ 88 struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ 89 unsigned long srcu_barrier_seq; /* srcu_barrier seq #. */ 90 struct mutex srcu_barrier_mutex; /* Serialize barrier ops. */ 91 struct completion srcu_barrier_completion; 92 /* Awaken barrier rq at end. */ 93 atomic_t srcu_barrier_cpu_cnt; /* # CPUs not yet posting a */ 94 /* callback for the barrier */ 95 /* operation. */ 96 struct delayed_work work; 97 #ifdef CONFIG_DEBUG_LOCK_ALLOC 98 struct lockdep_map dep_map; 99 #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ 100 }; 101 102 /* Values for state variable (bottom bits of ->srcu_gp_seq). */ 103 #define SRCU_STATE_IDLE 0 104 #define SRCU_STATE_SCAN1 1 105 #define SRCU_STATE_SCAN2 2 106 107 #define __SRCU_STRUCT_INIT(name, pcpu_name) \ 108 { \ 109 .sda = &pcpu_name, \ 110 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ 111 .srcu_gp_seq_needed = 0 - 1, \ 112 __SRCU_DEP_MAP_INIT(name) \ 113 } 114 115 /* 116 * Define and initialize a srcu struct at build time. 117 * Do -not- call init_srcu_struct() nor cleanup_srcu_struct() on it. 118 * 119 * Note that although DEFINE_STATIC_SRCU() hides the name from other 120 * files, the per-CPU variable rules nevertheless require that the 121 * chosen name be globally unique. These rules also prohibit use of 122 * DEFINE_STATIC_SRCU() within a function. If these rules are too 123 * restrictive, declare the srcu_struct manually. For example, in 124 * each file: 125 * 126 * static struct srcu_struct my_srcu; 127 * 128 * Then, before the first use of each my_srcu, manually initialize it: 129 * 130 * init_srcu_struct(&my_srcu); 131 * 132 * See include/linux/percpu-defs.h for the rules on per-CPU variables. 133 */ 134 #define __DEFINE_SRCU(name, is_static) \ 135 static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data);\ 136 is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name##_srcu_data) 137 #define DEFINE_SRCU(name) __DEFINE_SRCU(name, /* not static */) 138 #define DEFINE_STATIC_SRCU(name) __DEFINE_SRCU(name, static) 139 140 void synchronize_srcu_expedited(struct srcu_struct *sp); 141 void srcu_barrier(struct srcu_struct *sp); 142 void srcu_torture_stats_print(struct srcu_struct *sp, char *tt, char *tf); 143 144 #endif 145