Add missing rcu_cmpxchg_pointer define
[urcu.git] / urcu-defer-static.h
1 #ifndef _URCU_DEFER_STATIC_H
2 #define _URCU_DEFER_STATIC_H
3
4 /*
5 * urcu-defer-static.h
6 *
7 * Userspace RCU header - memory reclamation.
8 *
9 * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu-defer.h for linking
10 * dynamically with the userspace rcu reclamation library.
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 /*
40 * Number of entries in the per-thread defer queue. Must be power of 2.
41 */
42 #define DEFER_QUEUE_SIZE (1 << 12)
43 #define DEFER_QUEUE_MASK (DEFER_QUEUE_SIZE - 1)
44
45 /*
46 * Typically, data is aligned at least on the architecture size.
47 * Use lowest bit to indicate that the current callback is changing.
48 * Assumes that (void *)-2L is not used often. Used to encode non-aligned
49 * functions and non-aligned data using extra space.
50 * We encode the (void *)-2L fct as: -2L, fct, data.
51 * We encode the (void *)-2L data as: -2L, fct, data.
52 * Here, DQ_FCT_MARK == ~DQ_FCT_BIT. Required for the test order.
53 */
54 #define DQ_FCT_BIT (1 << 0)
55 #define DQ_IS_FCT_BIT(x) ((unsigned long)(x) & DQ_FCT_BIT)
56 #define DQ_SET_FCT_BIT(x) \
57 (x = (void *)((unsigned long)(x) | DQ_FCT_BIT))
58 #define DQ_CLEAR_FCT_BIT(x) \
59 (x = (void *)((unsigned long)(x) & ~DQ_FCT_BIT))
60 #define DQ_FCT_MARK ((void *)(~DQ_FCT_BIT))
61
62 /*
63 * Identify a shared load. A smp_rmc() or smp_mc() should come before the load.
64 */
65 #define _LOAD_SHARED(p) ACCESS_ONCE(p)
66
67 /*
68 * Load a data from shared memory, doing a cache flush if required.
69 */
70 #define LOAD_SHARED(p) \
71 ({ \
72 smp_rmc(); \
73 _LOAD_SHARED(p); \
74 })
75
76 /*
77 * Identify a shared store. A smp_wmc() or smp_mc() should follow the store.
78 */
79 #define _STORE_SHARED(x, v) ({ ACCESS_ONCE(x) = (v); })
80
81 /*
82 * Store v into x, where x is located in shared memory. Performs the required
83 * cache flush after writing. Returns v.
84 */
85 #define STORE_SHARED(x, v) \
86 ({ \
87 _STORE_SHARED(x, v); \
88 smp_wmc(); \
89 (v); \
90 })
91
92 /*
93 * This code section can only be included in LGPL 2.1 compatible source code.
94 * See below for the function call wrappers which can be used in code meant to
95 * be only linked with the Userspace RCU library. This comes with a small
96 * performance degradation on the read-side due to the added function calls.
97 * This is required to permit relinking with newer versions of the library.
98 */
99
100 #ifdef DEBUG_RCU
101 #define rcu_assert(args...) assert(args)
102 #else
103 #define rcu_assert(args...)
104 #endif
105
106 /*
107 * defer queue.
108 * Contains pointers. Encoded to save space when same callback is often used.
109 * When looking up the next item:
110 * - if DQ_FCT_BIT is set, set the current callback to DQ_CLEAR_FCT_BIT(ptr)
111 * - next element contains pointer to data.
112 * - else if item == DQ_FCT_MARK
113 * - set the current callback to next element ptr
114 * - following next element contains pointer to data.
115 * - else current element contains data
116 */
117 struct defer_queue {
118 unsigned long head; /* add element at head */
119 void *last_fct_in; /* last fct pointer encoded */
120 unsigned long tail; /* next element to remove at tail */
121 void *last_fct_out; /* last fct pointer encoded */
122 void **q;
123 };
124
125 #endif /* _URCU_DEFER_STATIC_H */
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