kernel/rcu/tiny_plugin.h

   1 /*
   2  * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition
   3  * Internal non-public definitions that provide either classic
   4  * or preemptible semantics.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, you can access it online at
  18  * http://www.gnu.org/licenses/gpl-2.0.html.
  19  *
  20  * Copyright (c) 2010 Linaro
  21  *
  22  * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
  23  */
  24
  25 #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU)
  26 #include <linux/kernel_stat.h>
  27
  28 int rcu_scheduler_active __read_mostly;
  29 EXPORT_SYMBOL_GPL(rcu_scheduler_active);
  30
  31 /*
  32  * During boot, we forgive RCU lockdep issues.  After this function is
  33  * invoked, we start taking RCU lockdep issues seriously.  Note that unlike
  34  * Tree RCU, Tiny RCU transitions directly from RCU_SCHEDULER_INACTIVE
  35  * to RCU_SCHEDULER_RUNNING, skipping the RCU_SCHEDULER_INIT stage.
  36  * The reason for this is that Tiny RCU does not need kthreads, so does
  37  * not have to care about the fact that the scheduler is half-initialized
  38  * at a certain phase of the boot process.  Unless SRCU is in the mix.
  39  */
  40 void __init rcu_scheduler_starting(void)
  41 {
  42         WARN_ON(nr_context_switches() > 0);
  43         rcu_scheduler_active = IS_ENABLED(CONFIG_SRCU)
  44                 ? RCU_SCHEDULER_INIT : RCU_SCHEDULER_RUNNING;
  45 }
  46
  47 #endif /* #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU) */