2 * Read-Copy Update mechanism for mutual exclusion
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18 * Copyright IBM Corporation, 2001
20 * Authors: Dipankar Sarma <dipankar@in.ibm.com>
21 * Manfred Spraul <manfred@colorfullife.com>
23 * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
24 * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
26 * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
27 * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
29 * For detailed explanation of Read-Copy Update mechanism see -
30 * http://lse.sourceforge.net/locking/rcupdate.html
33 #include <linux/types.h>
34 #include <linux/kernel.h>
35 #include <linux/init.h>
36 #include <linux/spinlock.h>
37 #include <linux/smp.h>
38 #include <linux/interrupt.h>
39 #include <linux/sched.h>
40 #include <asm/atomic.h>
41 #include <linux/bitops.h>
42 #include <linux/percpu.h>
43 #include <linux/notifier.h>
44 #include <linux/cpu.h>
45 #include <linux/mutex.h>
46 #include <linux/module.h>
47 #include <linux/kernel_stat.h>
49 #ifdef CONFIG_DEBUG_LOCK_ALLOC
50 static struct lock_class_key rcu_lock_key;
51 struct lockdep_map rcu_lock_map =
52 STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key);
53 EXPORT_SYMBOL_GPL(rcu_lock_map);
55 static struct lock_class_key rcu_bh_lock_key;
56 struct lockdep_map rcu_bh_lock_map =
57 STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_bh", &rcu_bh_lock_key);
58 EXPORT_SYMBOL_GPL(rcu_bh_lock_map);
60 static struct lock_class_key rcu_sched_lock_key;
61 struct lockdep_map rcu_sched_lock_map =
62 STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key);
63 EXPORT_SYMBOL_GPL(rcu_sched_lock_map);
66 int rcu_scheduler_active __read_mostly;
67 EXPORT_SYMBOL_GPL(rcu_scheduler_active);
70 * This function is invoked towards the end of the scheduler's initialization
71 * process. Before this is called, the idle task might contain
72 * RCU read-side critical sections (during which time, this idle
73 * task is booting the system). After this function is called, the
74 * idle tasks are prohibited from containing RCU read-side critical
77 void rcu_scheduler_starting(void)
79 WARN_ON(num_online_cpus() != 1);
80 WARN_ON(nr_context_switches() > 0);
81 rcu_scheduler_active = 1;
85 * Awaken the corresponding synchronize_rcu() instance now that a
86 * grace period has elapsed.
88 void wakeme_after_rcu(struct rcu_head *head)
90 struct rcu_synchronize *rcu;
92 rcu = container_of(head, struct rcu_synchronize, head);
93 complete(&rcu->completion);