Root/
1 | /* |
2 | * Read-Copy Update mechanism for mutual exclusion |
3 | * |
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. |
8 | * |
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. |
13 | * |
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. |
17 | * |
18 | * Copyright IBM Corporation, 2001 |
19 | * |
20 | * Authors: Dipankar Sarma <dipankar@in.ibm.com> |
21 | * Manfred Spraul <manfred@colorfullife.com> |
22 | * |
23 | * Based on the original work by Paul McKenney <paulmck@us.ibm.com> |
24 | * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. |
25 | * Papers: |
26 | * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf |
27 | * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001) |
28 | * |
29 | * For detailed explanation of Read-Copy Update mechanism see - |
30 | * http://lse.sourceforge.net/locking/rcupdate.html |
31 | * |
32 | */ |
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> |
48 | #include <linux/hardirq.h> |
49 | |
50 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
51 | static struct lock_class_key rcu_lock_key; |
52 | struct lockdep_map rcu_lock_map = |
53 | STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key); |
54 | EXPORT_SYMBOL_GPL(rcu_lock_map); |
55 | |
56 | static struct lock_class_key rcu_bh_lock_key; |
57 | struct lockdep_map rcu_bh_lock_map = |
58 | STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_bh", &rcu_bh_lock_key); |
59 | EXPORT_SYMBOL_GPL(rcu_bh_lock_map); |
60 | |
61 | static struct lock_class_key rcu_sched_lock_key; |
62 | struct lockdep_map rcu_sched_lock_map = |
63 | STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key); |
64 | EXPORT_SYMBOL_GPL(rcu_sched_lock_map); |
65 | #endif |
66 | |
67 | int rcu_scheduler_active __read_mostly; |
68 | EXPORT_SYMBOL_GPL(rcu_scheduler_active); |
69 | |
70 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
71 | |
72 | int debug_lockdep_rcu_enabled(void) |
73 | { |
74 | return rcu_scheduler_active && debug_locks && |
75 | current->lockdep_recursion == 0; |
76 | } |
77 | EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled); |
78 | |
79 | /** |
80 | * rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section? |
81 | * |
82 | * Check for bottom half being disabled, which covers both the |
83 | * CONFIG_PROVE_RCU and not cases. Note that if someone uses |
84 | * rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled) |
85 | * will show the situation. |
86 | * |
87 | * Check debug_lockdep_rcu_enabled() to prevent false positives during boot. |
88 | */ |
89 | int rcu_read_lock_bh_held(void) |
90 | { |
91 | if (!debug_lockdep_rcu_enabled()) |
92 | return 1; |
93 | return in_softirq(); |
94 | } |
95 | EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held); |
96 | |
97 | #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ |
98 | |
99 | /* |
100 | * This function is invoked towards the end of the scheduler's initialization |
101 | * process. Before this is called, the idle task might contain |
102 | * RCU read-side critical sections (during which time, this idle |
103 | * task is booting the system). After this function is called, the |
104 | * idle tasks are prohibited from containing RCU read-side critical |
105 | * sections. |
106 | */ |
107 | void rcu_scheduler_starting(void) |
108 | { |
109 | WARN_ON(num_online_cpus() != 1); |
110 | WARN_ON(nr_context_switches() > 0); |
111 | rcu_scheduler_active = 1; |
112 | } |
113 | |
114 | /* |
115 | * Awaken the corresponding synchronize_rcu() instance now that a |
116 | * grace period has elapsed. |
117 | */ |
118 | void wakeme_after_rcu(struct rcu_head *head) |
119 | { |
120 | struct rcu_synchronize *rcu; |
121 | |
122 | rcu = container_of(head, struct rcu_synchronize, head); |
123 | complete(&rcu->completion); |
124 | } |
125 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9