cregit-Linux how code gets into the kernel

Release 4.12 include/linux/srcuclassic.h

Directory: include/linux
 * Sleepable Read-Copy Update mechanism for mutual exclusion,
 *      classic v4.11 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
 * 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
 * Copyright (C) IBM Corporation, 2017
 * Author: Paul McKenney <>



struct srcu_array {
unsigned long lock_count[2];
unsigned long unlock_count[2];

struct rcu_batch {

struct rcu_head *head, **tail;

#define RCU_BATCH_INIT(name) { NULL, &(name.head) }

struct srcu_struct {
unsigned long completed;
struct srcu_array __percpu *per_cpu_ref;
spinlock_t queue_lock; /* protect ->batch_queue, ->running */
bool running;
	/* callbacks just queued */
struct rcu_batch batch_queue;
	/* callbacks try to do the first check_zero */
struct rcu_batch batch_check0;
	/* callbacks done with the first check_zero and the flip */
struct rcu_batch batch_check1;
struct rcu_batch batch_done;
struct delayed_work work;
struct lockdep_map dep_map;
#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */

void process_srcu(struct work_struct *work);

#define __SRCU_STRUCT_INIT(name)					\
	{                                                               \
                .completed = -300,                                      \
                .per_cpu_ref = &name##_srcu_array,                      \
                .queue_lock = __SPIN_LOCK_UNLOCKED(name.queue_lock),    \
                .running = false,                                       \
                .batch_queue = RCU_BATCH_INIT(name.batch_queue),        \
                .batch_check0 = RCU_BATCH_INIT(name.batch_check0),      \
                .batch_check1 = RCU_BATCH_INIT(name.batch_check1),      \
                .batch_done = RCU_BATCH_INIT(name.batch_done),          \
                .work = __DELAYED_WORK_INITIALIZER(, process_srcu, 0),\
                __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_array, name##_srcu_array);\
        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);
unsigned long srcu_batches_completed(struct srcu_struct *sp);

static inline void srcutorture_get_gp_data(enum rcutorture_type test_type, struct srcu_struct *sp, int *flags, unsigned long *gpnum, unsigned long *completed) { if (test_type != SRCU_FLAVOR) return; *flags = 0; *completed = sp->completed; *gpnum = *completed; if (sp->batch_queue.head || sp->batch_check0.head || sp->batch_check0.head) (*gpnum)++; }


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Directory: include/linux
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