Rename liburcu-reclaim to liburcu-defer
[urcu.git] / urcu-defer-static.h
CommitLineData
786ee85b
MD
1#ifndef _URCU_DEFER_STATIC_H
2#define _URCU_DEFER_STATIC_H
90075a50
MD
3
4/*
786ee85b 5 * urcu-defer-static.h
90075a50 6 *
658225a7 7 * Userspace RCU header - memory reclamation.
90075a50 8 *
786ee85b 9 * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu-defer.h for linking
658225a7 10 * dynamically with the userspace rcu reclamation library.
90075a50
MD
11 *
12 * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
13 * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
14 *
15 * This library is free software; you can redistribute it and/or
16 * modify it under the terms of the GNU Lesser General Public
17 * License as published by the Free Software Foundation; either
18 * version 2.1 of the License, or (at your option) any later version.
19 *
20 * This library is distributed in the hope that it will be useful,
21 * but WITHOUT ANY WARRANTY; without even the implied warranty of
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
23 * Lesser General Public License for more details.
24 *
25 * You should have received a copy of the GNU Lesser General Public
26 * License along with this library; if not, write to the Free Software
27 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
28 *
29 * IBM's contributions to this file may be relicensed under LGPLv2 or later.
30 */
31
32#include <stdlib.h>
33#include <pthread.h>
34
35#include <compiler.h>
36#include <arch.h>
37
38
39/*
786ee85b 40 * Number of entries in the per-thread defer queue. Must be power of 2.
90075a50 41 */
786ee85b
MD
42#define DEFER_QUEUE_SIZE (1 << 12)
43#define DEFER_QUEUE_MASK (DEFER_QUEUE_SIZE - 1)
90075a50
MD
44
45/*
46 * Identify a shared load. A smp_rmc() or smp_mc() should come before the load.
47 */
48#define _LOAD_SHARED(p) ACCESS_ONCE(p)
49
50/*
51 * Load a data from shared memory, doing a cache flush if required.
52 */
53#define LOAD_SHARED(p) \
54 ({ \
55 smp_rmc(); \
56 _LOAD_SHARED(p); \
57 })
58
59/*
60 * Identify a shared store. A smp_wmc() or smp_mc() should follow the store.
61 */
62#define _STORE_SHARED(x, v) ({ ACCESS_ONCE(x) = (v); })
63
64/*
65 * Store v into x, where x is located in shared memory. Performs the required
66 * cache flush after writing. Returns v.
67 */
68#define STORE_SHARED(x, v) \
69 ({ \
70 _STORE_SHARED(x, v); \
71 smp_wmc(); \
72 (v); \
73 })
74
75/*
76 * This code section can only be included in LGPL 2.1 compatible source code.
77 * See below for the function call wrappers which can be used in code meant to
78 * be only linked with the Userspace RCU library. This comes with a small
79 * performance degradation on the read-side due to the added function calls.
80 * This is required to permit relinking with newer versions of the library.
81 */
82
83#ifdef DEBUG_RCU
84#define rcu_assert(args...) assert(args)
85#else
86#define rcu_assert(args...)
87#endif
88
786ee85b 89struct defer_queue {
90075a50
MD
90 unsigned long head; /* add element at head */
91 unsigned long tail; /* next element to remove at tail */
92 void **q;
93};
94
786ee85b 95extern struct defer_queue __thread defer_queue;
90075a50 96
786ee85b 97extern void rcu_defer_barrier_thread(void);
90075a50
MD
98
99/*
100 * not signal-safe.
101 */
786ee85b 102static inline void _rcu_defer_queue(void *p)
90075a50
MD
103{
104 unsigned long head, tail;
105
106 /*
107 * Head is only modified by ourself. Tail can be modified by reclamation
108 * thread.
109 */
786ee85b
MD
110 head = defer_queue.head;
111 tail = LOAD_SHARED(defer_queue.tail);
90075a50
MD
112
113 /*
114 * If queue is full, empty it ourself.
115 */
786ee85b
MD
116 if (unlikely(head - tail >= DEFER_QUEUE_SIZE)) {
117 assert(head - tail == DEFER_QUEUE_SIZE);
118 rcu_defer_barrier_thread();
119 assert(head - LOAD_SHARED(defer_queue.tail) == 0);
90075a50
MD
120 }
121
122 smp_wmb(); /* Publish new pointer before write q[] */
786ee85b 123 _STORE_SHARED(defer_queue.q[head & DEFER_QUEUE_MASK], p);
90075a50 124 smp_wmb(); /* Write q[] before head. */
786ee85b 125 STORE_SHARED(defer_queue.head, head + 1);
90075a50
MD
126}
127
786ee85b 128#endif /* _URCU_DEFER_STATIC_H */
This page took 0.039217 seconds and 4 git commands to generate.