linux/include/linux/srcutree.h

/* SPDX-License-Identifier: GPL-2.0+ */
/*
 * Sleepable Read-Copy Update mechanism for mutual exclusion,
 *	tree variant.
 *
 * Copyright (C) IBM Corporation, 2017
 *
 * Author: Paul McKenney <[email protected]>
 */

#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 { … };

/*
 * Node in SRCU combining tree, similar in function to rcu_data.
 */
struct srcu_node { … };

/*
 * Per-SRCU-domain structure, update-side data linked from srcu_struct.
 */
struct srcu_usage { … };

/*
 * Per-SRCU-domain structure, similar in function to rcu_state.
 */
struct srcu_struct { … };

// Values for size state variable (->srcu_size_state).  Once the state
// has been set to SRCU_SIZE_ALLOC, the grace-period code advances through
// this state machine one step per grace period until the SRCU_SIZE_BIG state
// is reached.  Otherwise, the state machine remains in the SRCU_SIZE_SMALL
// state indefinitely.
#define SRCU_SIZE_SMALL …
#define SRCU_SIZE_ALLOC …
					//  and then referenced by ->node.  It will not be used.
#define SRCU_SIZE_WAIT_BARRIER …
					//  except call_srcu(), especially by srcu_barrier().
					//  By the end of this state, all CPUs and threads
					//  are aware of this tree's existence.
#define SRCU_SIZE_WAIT_CALL …
					//  By the end of this state, all of the call_srcu()
					//  invocations that were running on a non-boot CPU
					//  and using the boot CPU's callback queue will have
					//  completed.
#define SRCU_SIZE_WAIT_CBS1 …
#define SRCU_SIZE_WAIT_CBS2 …
#define SRCU_SIZE_WAIT_CBS3 …
#define SRCU_SIZE_WAIT_CBS4 …
#define SRCU_SIZE_BIG …
					//  and all aspects of it are being put to use.

/* Values for state variable (bottom bits of ->srcu_gp_seq). */
#define SRCU_STATE_IDLE …
#define SRCU_STATE_SCAN1 …
#define SRCU_STATE_SCAN2 …

/*
 * Values for initializing gp sequence fields. Higher values allow wrap arounds to
 * occur earlier.
 * The second value with state is useful in the case of static initialization of
 * srcu_usage where srcu_gp_seq_needed is expected to have some state value in its
 * lower bits (or else it will appear to be already initialized within
 * the call check_init_srcu_struct()).
 */
#define SRCU_GP_SEQ_INITIAL_VAL …
#define SRCU_GP_SEQ_INITIAL_VAL_WITH_STATE …

#define __SRCU_USAGE_INIT(name) …

#define __SRCU_STRUCT_INIT_COMMON(name, usage_name) …

#define __SRCU_STRUCT_INIT_MODULE(name, usage_name) …

#define __SRCU_STRUCT_INIT(name, usage_name, pcpu_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.
 */
#ifdef MODULE
#define __DEFINE_SRCU …
#else
#define __DEFINE_SRCU(name, is_static) …
#endif
#define DEFINE_SRCU(name) …
#define DEFINE_STATIC_SRCU(name) …

void synchronize_srcu_expedited(struct srcu_struct *ssp);
void srcu_barrier(struct srcu_struct *ssp);
void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf);

#endif