Restrict supported arch ot P6+ on Intel x86 32.
[urcu.git] / urcu-defer-static.h
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1#ifndef _URCU_DEFER_STATIC_H
2#define _URCU_DEFER_STATIC_H
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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.
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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
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35#include <urcu/compiler.h>
36#include <urcu/arch.h>
48d848c7 37#include <urcu/uatomic_arch.h>
dbc6128f 38#include <urcu/list.h>
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39
40
41/*
786ee85b 42 * Number of entries in the per-thread defer queue. Must be power of 2.
90075a50 43 */
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44#define DEFER_QUEUE_SIZE (1 << 12)
45#define DEFER_QUEUE_MASK (DEFER_QUEUE_SIZE - 1)
90075a50 46
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47/*
48 * Typically, data is aligned at least on the architecture size.
49 * Use lowest bit to indicate that the current callback is changing.
50 * Assumes that (void *)-2L is not used often. Used to encode non-aligned
51 * functions and non-aligned data using extra space.
52 * We encode the (void *)-2L fct as: -2L, fct, data.
53 * We encode the (void *)-2L data as: -2L, fct, data.
54 * Here, DQ_FCT_MARK == ~DQ_FCT_BIT. Required for the test order.
55 */
56#define DQ_FCT_BIT (1 << 0)
57#define DQ_IS_FCT_BIT(x) ((unsigned long)(x) & DQ_FCT_BIT)
58#define DQ_SET_FCT_BIT(x) \
59 (x = (void *)((unsigned long)(x) | DQ_FCT_BIT))
60#define DQ_CLEAR_FCT_BIT(x) \
61 (x = (void *)((unsigned long)(x) & ~DQ_FCT_BIT))
62#define DQ_FCT_MARK ((void *)(~DQ_FCT_BIT))
63
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64/*
65 * Identify a shared load. A smp_rmc() or smp_mc() should come before the load.
66 */
67#define _LOAD_SHARED(p) ACCESS_ONCE(p)
68
69/*
70 * Load a data from shared memory, doing a cache flush if required.
71 */
72#define LOAD_SHARED(p) \
73 ({ \
74 smp_rmc(); \
75 _LOAD_SHARED(p); \
76 })
77
78/*
79 * Identify a shared store. A smp_wmc() or smp_mc() should follow the store.
80 */
81#define _STORE_SHARED(x, v) ({ ACCESS_ONCE(x) = (v); })
82
83/*
84 * Store v into x, where x is located in shared memory. Performs the required
85 * cache flush after writing. Returns v.
86 */
87#define STORE_SHARED(x, v) \
88 ({ \
89 _STORE_SHARED(x, v); \
90 smp_wmc(); \
91 (v); \
92 })
93
94/*
95 * This code section can only be included in LGPL 2.1 compatible source code.
96 * See below for the function call wrappers which can be used in code meant to
97 * be only linked with the Userspace RCU library. This comes with a small
98 * performance degradation on the read-side due to the added function calls.
99 * This is required to permit relinking with newer versions of the library.
100 */
101
102#ifdef DEBUG_RCU
103#define rcu_assert(args...) assert(args)
104#else
105#define rcu_assert(args...)
106#endif
107
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108/*
109 * defer queue.
110 * Contains pointers. Encoded to save space when same callback is often used.
111 * When looking up the next item:
112 * - if DQ_FCT_BIT is set, set the current callback to DQ_CLEAR_FCT_BIT(ptr)
113 * - next element contains pointer to data.
114 * - else if item == DQ_FCT_MARK
115 * - set the current callback to next element ptr
116 * - following next element contains pointer to data.
117 * - else current element contains data
118 */
786ee85b 119struct defer_queue {
90075a50 120 unsigned long head; /* add element at head */
804b4375 121 void *last_fct_in; /* last fct pointer encoded */
90075a50 122 unsigned long tail; /* next element to remove at tail */
804b4375 123 void *last_fct_out; /* last fct pointer encoded */
90075a50 124 void **q;
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125 /* registry information */
126 unsigned long last_head;
127 struct list_head list; /* list of thread queues */
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128};
129
786ee85b 130#endif /* _URCU_DEFER_STATIC_H */
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