Rename `urcu_assert()` to `urcu_assert_debug()`
[urcu.git] / include / urcu / static / urcu-common.h
... / ...
CommitLineData
1#ifndef _URCU_COMMON_STATIC_H
2#define _URCU_COMMON_STATIC_H
3
4/*
5 * urcu-common-static.h
6 *
7 * Userspace RCU header.
8 *
9 * TO BE INCLUDED ONLY IN CODE THAT IS TO BE RECOMPILED ON EACH LIBURCU
10 * RELEASE. See urcu.h for linking dynamically with the userspace rcu library.
11 *
12 * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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#include <unistd.h>
35#include <stdint.h>
36
37#include <urcu/config.h>
38#include <urcu/compiler.h>
39#include <urcu/arch.h>
40#include <urcu/system.h>
41#include <urcu/uatomic.h>
42#include <urcu/list.h>
43#include <urcu/futex.h>
44#include <urcu/tls-compat.h>
45#include <urcu/debug.h>
46
47#ifdef __cplusplus
48extern "C" {
49#endif
50
51enum urcu_state {
52 URCU_READER_ACTIVE_CURRENT,
53 URCU_READER_ACTIVE_OLD,
54 URCU_READER_INACTIVE,
55};
56
57/*
58 * The trick here is that URCU_GP_CTR_PHASE must be a multiple of 8 so
59 * we can use a full 8-bits, 16-bits or 32-bits bitmask for the lower
60 * order bits.
61 */
62#define URCU_GP_COUNT (1UL << 0)
63/* Use the amount of bits equal to half of the architecture long size */
64#define URCU_GP_CTR_PHASE (1UL << (sizeof(unsigned long) << 2))
65#define URCU_GP_CTR_NEST_MASK (URCU_GP_CTR_PHASE - 1)
66
67struct urcu_gp {
68 /*
69 * Global grace period counter.
70 * Contains the current URCU_GP_CTR_PHASE.
71 * Also has a URCU_GP_COUNT of 1, to accelerate the reader fast path.
72 * Written to only by writer with mutex taken.
73 * Read by both writer and readers.
74 */
75 unsigned long ctr;
76
77 int32_t futex;
78} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
79
80struct urcu_reader {
81 /* Data used by both reader and synchronize_rcu() */
82 unsigned long ctr;
83 char need_mb;
84 /* Data used for registry */
85 struct cds_list_head node __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
86 pthread_t tid;
87 /* Reader registered flag, for internal checks. */
88 unsigned int registered:1;
89};
90
91/*
92 * Wake-up waiting synchronize_rcu(). Called from many concurrent threads.
93 */
94static inline void urcu_common_wake_up_gp(struct urcu_gp *gp)
95{
96 if (caa_unlikely(uatomic_read(&gp->futex) == -1)) {
97 uatomic_set(&gp->futex, 0);
98 /*
99 * Ignoring return value until we can make this function
100 * return something (because urcu_die() is not publicly
101 * exposed).
102 */
103 (void) futex_async(&gp->futex, FUTEX_WAKE, 1,
104 NULL, NULL, 0);
105 }
106}
107
108static inline enum urcu_state urcu_common_reader_state(struct urcu_gp *gp,
109 unsigned long *ctr)
110{
111 unsigned long v;
112
113 /*
114 * Make sure both tests below are done on the same version of *value
115 * to insure consistency.
116 */
117 v = CMM_LOAD_SHARED(*ctr);
118 if (!(v & URCU_GP_CTR_NEST_MASK))
119 return URCU_READER_INACTIVE;
120 if (!((v ^ gp->ctr) & URCU_GP_CTR_PHASE))
121 return URCU_READER_ACTIVE_CURRENT;
122 return URCU_READER_ACTIVE_OLD;
123}
124
125#ifdef __cplusplus
126}
127#endif
128
129#endif /* _URCU_COMMON_STATIC_H */
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