/* * Sleepable Read-Copy Update mechanism for mutual exclusion, * tree variant. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, you can access it online at * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright (C) IBM Corporation, 2017 * * Author: Paul McKenney <paulmck@us.ibm.com> */ #ifndef _LINUX_SRCU_TREE_H #define _LINUX_SRCU_TREE_H #include <linux/rcu_node_tree.h> #include <linux/completion.h> struct srcu_node; struct srcu_struct; /* * Per-CPU structure feeding into leaf srcu_node, similar in function * to rcu_node. */ struct srcu_data { /* Read-side state. */ unsigned long srcu_lock_count[2]; /* Locks per CPU. */ unsigned long srcu_unlock_count[2]; /* Unlocks per CPU. */ /* Update-side state. */ raw_spinlock_t __private lock ____cacheline_internodealigned_in_smp; struct rcu_segcblist srcu_cblist; /* List of callbacks.*/ unsigned long srcu_gp_seq_needed; /* Furthest future GP needed. */ unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */ bool srcu_cblist_invoking; /* Invoking these CBs? */ struct delayed_work work; /* Context for CB invoking. */ struct rcu_head srcu_barrier_head; /* For srcu_barrier() use. */ struct srcu_node *mynode; /* Leaf srcu_node. */ unsigned long grpmask; /* Mask for leaf srcu_node */ /* ->srcu_data_have_cbs[]. */ int cpu; struct srcu_struct *sp; }; /* * Node in SRCU combining tree, similar in function to rcu_data. */ struct srcu_node { raw_spinlock_t __private lock; unsigned long srcu_have_cbs[4]; /* GP seq for children */ /* having CBs, but only */ /* is > ->srcu_gq_seq. */ unsigned long srcu_data_have_cbs[4]; /* Which srcu_data structs */ /* have CBs for given GP? */ unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */ struct srcu_node *srcu_parent; /* Next up in tree. */ int grplo; /* Least CPU for node. */ int grphi; /* Biggest CPU for node. */ }; /* * Per-SRCU-domain structure, similar in function to rcu_state. */ struct srcu_struct { struct srcu_node node[NUM_RCU_NODES]; /* Combining tree. */ struct srcu_node *level[RCU_NUM_LVLS + 1]; /* First node at each level. */ struct mutex srcu_cb_mutex; /* Serialize CB preparation. */ raw_spinlock_t __private lock; /* Protect counters */ struct mutex srcu_gp_mutex; /* Serialize GP work. */ unsigned int srcu_idx; /* Current rdr array element. */ unsigned long srcu_gp_seq; /* Grace-period seq #. */ unsigned long srcu_gp_seq_needed; /* Latest gp_seq needed. */ unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */ unsigned long srcu_last_gp_end; /* Last GP end timestamp (ns) */ struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ unsigned long srcu_barrier_seq; /* srcu_barrier seq #. */ struct mutex srcu_barrier_mutex; /* Serialize barrier ops. */ struct completion srcu_barrier_completion; /* Awaken barrier rq at end. */ atomic_t srcu_barrier_cpu_cnt; /* # CPUs not yet posting a */ /* callback for the barrier */ /* operation. */ struct delayed_work work; #ifdef CONFIG_DEBUG_LOCK_ALLOC struct lockdep_map dep_map; #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ }; /* Values for state variable (bottom bits of ->srcu_gp_seq). */ #define SRCU_STATE_IDLE 0 #define SRCU_STATE_SCAN1 1 #define SRCU_STATE_SCAN2 2 #define __SRCU_STRUCT_INIT(name) \ { \ .sda = &name##_srcu_data, \ .lock = __RAW_SPIN_LOCK_UNLOCKED(name.lock), \ .srcu_gp_seq_needed = 0 - 1, \ __SRCU_DEP_MAP_INIT(name) \ } /* * Define and initialize a srcu struct at build time. * Do -not- call init_srcu_struct() nor cleanup_srcu_struct() on it. * * Note that although DEFINE_STATIC_SRCU() hides the name from other * files, the per-CPU variable rules nevertheless require that the * chosen name be globally unique. These rules also prohibit use of * DEFINE_STATIC_SRCU() within a function. If these rules are too * restrictive, declare the srcu_struct manually. For example, in * each file: * * static struct srcu_struct my_srcu; * * Then, before the first use of each my_srcu, manually initialize it: * * init_srcu_struct(&my_srcu); * * See include/linux/percpu-defs.h for the rules on per-CPU variables. */ #define __DEFINE_SRCU(name, is_static) \ static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data);\ is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name) #define DEFINE_SRCU(name) __DEFINE_SRCU(name, /* not static */) #define DEFINE_STATIC_SRCU(name) __DEFINE_SRCU(name, static) void synchronize_srcu_expedited(struct srcu_struct *sp); void srcu_barrier(struct srcu_struct *sp); void srcu_torture_stats_print(struct srcu_struct *sp, char *tt, char *tf); #endif