1 #ifndef _URCU_DEFER_STATIC_H
2 #define _URCU_DEFER_STATIC_H
7 * Userspace RCU header - memory reclamation.
9 * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu-defer.h for linking
10 * dynamically with the userspace rcu reclamation library.
12 * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
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.
40 * Number of entries in the per-thread defer queue. Must be power of 2.
42 #define DEFER_QUEUE_SIZE (1 << 12)
43 #define DEFER_QUEUE_MASK (DEFER_QUEUE_SIZE - 1)
46 * Identify a shared load. A smp_rmc() or smp_mc() should come before the load.
48 #define _LOAD_SHARED(p) ACCESS_ONCE(p)
51 * Load a data from shared memory, doing a cache flush if required.
53 #define LOAD_SHARED(p) \
60 * Identify a shared store. A smp_wmc() or smp_mc() should follow the store.
62 #define _STORE_SHARED(x, v) ({ ACCESS_ONCE(x) = (v); })
65 * Store v into x, where x is located in shared memory. Performs the required
66 * cache flush after writing. Returns v.
68 #define STORE_SHARED(x, v) \
70 _STORE_SHARED(x, v); \
76 * This code section can only be included in LGPL 2.1 compatible source code.
77 * See below for the function call wrappers which can be used in code meant to
78 * be only linked with the Userspace RCU library. This comes with a small
79 * performance degradation on the read-side due to the added function calls.
80 * This is required to permit relinking with newer versions of the library.
84 #define rcu_assert(args...) assert(args)
86 #define rcu_assert(args...)
90 unsigned long head
; /* add element at head */
91 unsigned long tail
; /* next element to remove at tail */
95 extern struct defer_queue __thread defer_queue
;
97 extern void rcu_defer_barrier_thread(void);
102 static inline void _rcu_defer_queue(void *p
)
104 unsigned long head
, tail
;
107 * Head is only modified by ourself. Tail can be modified by reclamation
110 head
= defer_queue
.head
;
111 tail
= LOAD_SHARED(defer_queue
.tail
);
114 * If queue is full, empty it ourself.
116 if (unlikely(head
- tail
>= DEFER_QUEUE_SIZE
)) {
117 assert(head
- tail
== DEFER_QUEUE_SIZE
);
118 rcu_defer_barrier_thread();
119 assert(head
- LOAD_SHARED(defer_queue
.tail
) == 0);
122 smp_wmb(); /* Publish new pointer before write q[] */
123 _STORE_SHARED(defer_queue
.q
[head
& DEFER_QUEUE_MASK
], p
);
124 smp_wmb(); /* Write q[] before head. */
125 STORE_SHARED(defer_queue
.head
, head
+ 1);
128 #endif /* _URCU_DEFER_STATIC_H */