urcu/annotate: Add CMM annotation
[urcu.git] / include / urcu / static / urcu-common.h
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1// SPDX-FileCopyrightText: 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
2// SPDX-FileCopyrightText: 2009 Paul E. McKenney, IBM Corporation.
3//
4// SPDX-License-Identifier: LGPL-2.1-or-later
5
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6#ifndef _URCU_COMMON_STATIC_H
7#define _URCU_COMMON_STATIC_H
8
9/*
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10 * Userspace RCU header.
11 *
12 * TO BE INCLUDED ONLY IN CODE THAT IS TO BE RECOMPILED ON EACH LIBURCU
13 * RELEASE. See urcu.h for linking dynamically with the userspace rcu library.
14 *
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15 * IBM's contributions to this file may be relicensed under LGPLv2 or later.
16 */
17
18#include <stdlib.h>
19#include <pthread.h>
20#include <unistd.h>
21#include <stdint.h>
22
601922a8 23#include <urcu/annotate.h>
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24#include <urcu/config.h>
25#include <urcu/compiler.h>
26#include <urcu/arch.h>
27#include <urcu/system.h>
28#include <urcu/uatomic.h>
29#include <urcu/list.h>
30#include <urcu/futex.h>
31#include <urcu/tls-compat.h>
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32
33#ifdef __cplusplus
34extern "C" {
35#endif
36
37enum urcu_state {
38 URCU_READER_ACTIVE_CURRENT,
39 URCU_READER_ACTIVE_OLD,
40 URCU_READER_INACTIVE,
41};
42
43/*
44 * The trick here is that URCU_GP_CTR_PHASE must be a multiple of 8 so
45 * we can use a full 8-bits, 16-bits or 32-bits bitmask for the lower
46 * order bits.
47 */
48#define URCU_GP_COUNT (1UL << 0)
49/* Use the amount of bits equal to half of the architecture long size */
50#define URCU_GP_CTR_PHASE (1UL << (sizeof(unsigned long) << 2))
51#define URCU_GP_CTR_NEST_MASK (URCU_GP_CTR_PHASE - 1)
52
53struct urcu_gp {
54 /*
55 * Global grace period counter.
56 * Contains the current URCU_GP_CTR_PHASE.
57 * Also has a URCU_GP_COUNT of 1, to accelerate the reader fast path.
58 * Written to only by writer with mutex taken.
59 * Read by both writer and readers.
60 */
61 unsigned long ctr;
62
63 int32_t futex;
64} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
65
66struct urcu_reader {
67 /* Data used by both reader and synchronize_rcu() */
68 unsigned long ctr;
69 char need_mb;
70 /* Data used for registry */
71 struct cds_list_head node __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
72 pthread_t tid;
73 /* Reader registered flag, for internal checks. */
74 unsigned int registered:1;
75};
76
77/*
78 * Wake-up waiting synchronize_rcu(). Called from many concurrent threads.
79 */
80static inline void urcu_common_wake_up_gp(struct urcu_gp *gp)
81{
82 if (caa_unlikely(uatomic_read(&gp->futex) == -1)) {
83 uatomic_set(&gp->futex, 0);
84 /*
85 * Ignoring return value until we can make this function
86 * return something (because urcu_die() is not publicly
87 * exposed).
88 */
89 (void) futex_async(&gp->futex, FUTEX_WAKE, 1,
90 NULL, NULL, 0);
91 }
92}
93
94static inline enum urcu_state urcu_common_reader_state(struct urcu_gp *gp,
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95 unsigned long *ctr,
96 cmm_annotate_t *group)
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97{
98 unsigned long v;
99
100 /*
101 * Make sure both tests below are done on the same version of *value
102 * to insure consistency.
103 */
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104 v = uatomic_load(ctr, CMM_RELAXED);
105 cmm_annotate_group_mem_acquire(group, ctr);
106
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107 if (!(v & URCU_GP_CTR_NEST_MASK))
108 return URCU_READER_INACTIVE;
109 if (!((v ^ gp->ctr) & URCU_GP_CTR_PHASE))
110 return URCU_READER_ACTIVE_CURRENT;
111 return URCU_READER_ACTIVE_OLD;
112}
113
114#ifdef __cplusplus
115}
116#endif
117
118#endif /* _URCU_COMMON_STATIC_H */
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