include/linux/srcuclassic.h

   1 /*
   2  * Sleepable Read-Copy Update mechanism for mutual exclusion,
   3  *      classic v4.11 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_CLASSIC_H
  25 #define _LINUX_SRCU_CLASSIC_H
  26
  27 struct srcu_array {
  28         unsigned long lock_count[2];
  29         unsigned long unlock_count[2];
  30 };
  31
  32 struct rcu_batch {
  33         struct rcu_head *head, **tail;
  34 };
  35
  36 #define RCU_BATCH_INIT(name) { NULL, &(name.head) }
  37
  38 struct srcu_struct {
  39         unsigned long completed;
  40         struct srcu_array __percpu *per_cpu_ref;
  41         spinlock_t queue_lock; /* protect ->batch_queue, ->running */
  42         bool running;
  43         /* callbacks just queued */
  44         struct rcu_batch batch_queue;
  45         /* callbacks try to do the first check_zero */
  46         struct rcu_batch batch_check0;
  47         /* callbacks done with the first check_zero and the flip */
  48         struct rcu_batch batch_check1;
  49         struct rcu_batch batch_done;
  50         struct delayed_work work;
  51 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  52         struct lockdep_map dep_map;
  53 #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
  54 };
  55
  56 void process_srcu(struct work_struct *work);
  57
  58 #define __SRCU_STRUCT_INIT(name)                                        \
  59         {                                                               \
  60                 .completed = -300,                                      \
  61                 .per_cpu_ref = &name##_srcu_array,                      \
  62                 .queue_lock = __SPIN_LOCK_UNLOCKED(name.queue_lock),    \
  63                 .running = false,                                       \
  64                 .batch_queue = RCU_BATCH_INIT(name.batch_queue),        \
  65                 .batch_check0 = RCU_BATCH_INIT(name.batch_check0),      \
  66                 .batch_check1 = RCU_BATCH_INIT(name.batch_check1),      \
  67                 .batch_done = RCU_BATCH_INIT(name.batch_done),          \
  68                 .work = __DELAYED_WORK_INITIALIZER(name.work, process_srcu, 0),\
  69                 __SRCU_DEP_MAP_INIT(name)                               \
  70         }
  71
  72 /*
  73  * Define and initialize a srcu struct at build time.
  74  * Do -not- call init_srcu_struct() nor cleanup_srcu_struct() on it.
  75  *
  76  * Note that although DEFINE_STATIC_SRCU() hides the name from other
  77  * files, the per-CPU variable rules nevertheless require that the
  78  * chosen name be globally unique.  These rules also prohibit use of
  79  * DEFINE_STATIC_SRCU() within a function.  If these rules are too
  80  * restrictive, declare the srcu_struct manually.  For example, in
  81  * each file:
  82  *
  83  *      static struct srcu_struct my_srcu;
  84  *
  85  * Then, before the first use of each my_srcu, manually initialize it:
  86  *
  87  *      init_srcu_struct(&my_srcu);
  88  *
  89  * See include/linux/percpu-defs.h for the rules on per-CPU variables.
  90  */
  91 #define __DEFINE_SRCU(name, is_static)                                  \
  92         static DEFINE_PER_CPU(struct srcu_array, name##_srcu_array);\
  93         is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name)
  94 #define DEFINE_SRCU(name)               __DEFINE_SRCU(name, /* not static */)
  95 #define DEFINE_STATIC_SRCU(name)        __DEFINE_SRCU(name, static)
  96
  97 void synchronize_srcu_expedited(struct srcu_struct *sp);
  98 void srcu_barrier(struct srcu_struct *sp);
  99 unsigned long srcu_batches_completed(struct srcu_struct *sp);
 100
 101 static inline void srcutorture_get_gp_data(enum rcutorture_type test_type,
 102                                            struct srcu_struct *sp, int *flags,
 103                                            unsigned long *gpnum,
 104                                            unsigned long *completed)
 105 {
 106         if (test_type != SRCU_FLAVOR)
 107                 return;
 108         *flags = 0;
 109         *completed = sp->completed;
 110         *gpnum = *completed;
 111         if (sp->batch_queue.head || sp->batch_check0.head || sp->batch_check0.head)
 112                 (*gpnum)++;
 113 }
 114
 115 #endif