1 #ifndef _URCU_QSBR_STATIC_H
2 #define _URCU_QSBR_STATIC_H
7 * Userspace RCU QSBR header.
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.
12 * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
13 * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
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.
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.
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
29 * IBM's contributions to this file may be relicensed under LGPLv2 or later.
39 #include <urcu/compiler.h>
40 #include <urcu/arch.h>
41 #include <urcu/system.h>
42 #include <urcu/uatomic.h>
43 #include <urcu/list.h>
44 #include <urcu/futex.h>
45 #include <urcu/tls-compat.h>
52 * This code section can only be included in LGPL 2.1 compatible source code.
53 * See below for the function call wrappers which can be used in code meant to
54 * be only linked with the Userspace RCU library. This comes with a small
55 * performance degradation on the read-side due to the added function calls.
56 * This is required to permit relinking with newer versions of the library.
60 #define rcu_assert(args...) assert(args)
62 #define rcu_assert(args...)
71 #define YIELD_READ (1 << 0)
72 #define YIELD_WRITE (1 << 1)
74 /* maximum sleep delay, in us */
77 extern unsigned int yield_active
;
78 extern DECLARE_URCU_TLS(unsigned int, rand_yield
);
80 static inline void debug_yield_read(void)
82 if (yield_active
& YIELD_READ
)
83 if (rand_r(&URCU_TLS(rand_yield
)) & 0x1)
84 usleep(rand_r(&URCU_TLS(rand_yield
)) % MAX_SLEEP
);
87 static inline void debug_yield_write(void)
89 if (yield_active
& YIELD_WRITE
)
90 if (rand_r(&URCU_TLS(rand_yield
)) & 0x1)
91 usleep(rand_r(&URCU_TLS(rand_yield
)) % MAX_SLEEP
);
94 static inline void debug_yield_init(void)
96 URCU_TLS(rand_yield
) = time(NULL
) ^ pthread_self();
99 static inline void debug_yield_read(void)
103 static inline void debug_yield_write(void)
107 static inline void debug_yield_init(void)
113 #define RCU_GP_ONLINE (1UL << 0)
114 #define RCU_GP_CTR (1UL << 1)
117 * Global quiescent period counter with low-order bits unused.
118 * Using a int rather than a char to eliminate false register dependencies
119 * causing stalls on some architectures.
121 extern unsigned long rcu_gp_ctr
;
124 /* Data used by both reader and synchronize_rcu() */
126 /* Data used for registry */
127 struct cds_list_head node
__attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
132 extern DECLARE_URCU_TLS(struct rcu_reader
, rcu_reader
);
134 extern int32_t gp_futex
;
137 * Wake-up waiting synchronize_rcu(). Called from many concurrent threads.
139 static inline void wake_up_gp(void)
141 if (caa_unlikely(_CMM_LOAD_SHARED(URCU_TLS(rcu_reader
).waiting
))) {
142 _CMM_STORE_SHARED(URCU_TLS(rcu_reader
).waiting
, 0);
144 if (uatomic_read(&gp_futex
) != -1)
146 uatomic_set(&gp_futex
, 0);
147 futex_noasync(&gp_futex
, FUTEX_WAKE
, 1,
152 static inline int rcu_gp_ongoing(unsigned long *ctr
)
156 v
= CMM_LOAD_SHARED(*ctr
);
157 return v
&& (v
!= rcu_gp_ctr
);
161 * Enter an RCU read-side critical section.
163 * This function is less than 10 lines long. The intent is that this
164 * function meets the 10-line criterion for LGPL, allowing this function
165 * to be invoked directly from non-LGPL code.
167 static inline void _rcu_read_lock(void)
169 rcu_assert(URCU_TLS(rcu_reader
).ctr
);
173 * Exit an RCU read-side critical section.
175 * This function is less than 10 lines long. The intent is that this
176 * function meets the 10-line criterion for LGPL, allowing this function
177 * to be invoked directly from non-LGPL code.
179 static inline void _rcu_read_unlock(void)
184 * Inform RCU of a quiescent state.
186 * This function is less than 10 lines long. The intent is that this
187 * function meets the 10-line criterion for LGPL, allowing this function
188 * to be invoked directly from non-LGPL code.
190 static inline void _rcu_quiescent_state(void)
193 _CMM_STORE_SHARED(URCU_TLS(rcu_reader
).ctr
, _CMM_LOAD_SHARED(rcu_gp_ctr
));
194 cmm_smp_mb(); /* write URCU_TLS(rcu_reader).ctr before read futex */
200 * Take a thread offline, prohibiting it from entering further RCU
201 * read-side critical sections.
203 * This function is less than 10 lines long. The intent is that this
204 * function meets the 10-line criterion for LGPL, allowing this function
205 * to be invoked directly from non-LGPL code.
207 static inline void _rcu_thread_offline(void)
210 CMM_STORE_SHARED(URCU_TLS(rcu_reader
).ctr
, 0);
211 cmm_smp_mb(); /* write URCU_TLS(rcu_reader).ctr before read futex */
213 cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */
217 * Bring a thread online, allowing it to once again enter RCU
218 * read-side critical sections.
220 * This function is less than 10 lines long. The intent is that this
221 * function meets the 10-line criterion for LGPL, allowing this function
222 * to be invoked directly from non-LGPL code.
224 static inline void _rcu_thread_online(void)
226 cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */
227 _CMM_STORE_SHARED(URCU_TLS(rcu_reader
).ctr
, CMM_LOAD_SHARED(rcu_gp_ctr
));
235 #endif /* _URCU_QSBR_STATIC_H */
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