include/linux/srcutree.h

   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 struct srcu_array {
  28         unsigned long lock_count[2];
  29         unsigned long unlock_count[2];
  30 };
  31
  32 struct srcu_struct {
  33         unsigned long completed;
  34         unsigned long srcu_gp_seq;
  35         atomic_t srcu_exp_cnt;
  36         struct srcu_array __percpu *per_cpu_ref;
  37         spinlock_t queue_lock; /* protect ->srcu_cblist */
  38         struct rcu_segcblist srcu_cblist;
  39         struct delayed_work work;
  40 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  41         struct lockdep_map dep_map;
  42 #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
  43 };
  44
  45 /* Values for -> state variable. */
  46 #define SRCU_STATE_IDLE         0
  47 #define SRCU_STATE_SCAN1        1
  48 #define SRCU_STATE_SCAN2        2
  49
  50 void process_srcu(struct work_struct *work);
  51
  52 #define __SRCU_STRUCT_INIT(name)                                        \
  53         {                                                               \
  54                 .completed = -300,                                      \
  55                 .per_cpu_ref = &name##_srcu_array,                      \
  56                 .queue_lock = __SPIN_LOCK_UNLOCKED(name.queue_lock),    \
  57                 .srcu_cblist = RCU_SEGCBLIST_INITIALIZER(name.srcu_cblist),\
  58                 .work = __DELAYED_WORK_INITIALIZER(name.work, process_srcu, 0),\
  59                 __SRCU_DEP_MAP_INIT(name)                               \
  60         }
  61
  62 /*
  63  * Define and initialize a srcu struct at build time.
  64  * Do -not- call init_srcu_struct() nor cleanup_srcu_struct() on it.
  65  *
  66  * Note that although DEFINE_STATIC_SRCU() hides the name from other
  67  * files, the per-CPU variable rules nevertheless require that the
  68  * chosen name be globally unique.  These rules also prohibit use of
  69  * DEFINE_STATIC_SRCU() within a function.  If these rules are too
  70  * restrictive, declare the srcu_struct manually.  For example, in
  71  * each file:
  72  *
  73  *      static struct srcu_struct my_srcu;
  74  *
  75  * Then, before the first use of each my_srcu, manually initialize it:
  76  *
  77  *      init_srcu_struct(&my_srcu);
  78  *
  79  * See include/linux/percpu-defs.h for the rules on per-CPU variables.
  80  */
  81 #define __DEFINE_SRCU(name, is_static)                                  \
  82         static DEFINE_PER_CPU(struct srcu_array, name##_srcu_array);\
  83         is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name)
  84 #define DEFINE_SRCU(name)               __DEFINE_SRCU(name, /* not static */)
  85 #define DEFINE_STATIC_SRCU(name)        __DEFINE_SRCU(name, static)
  86
  87 void synchronize_srcu_expedited(struct srcu_struct *sp);
  88 void srcu_barrier(struct srcu_struct *sp);
  89 unsigned long srcu_batches_completed(struct srcu_struct *sp);
  90
  91 #endif