[userspace-rcu.git] / urcu-defer-static.h

#ifndef _URCU_DEFER_STATIC_H
#define _URCU_DEFER_STATIC_H

/*
 * urcu-defer-static.h
 *
 * Userspace RCU header - memory reclamation.
 *
 * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu-defer.h for linking
 * dynamically with the userspace rcu reclamation library.
 *
 * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
 * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * IBM's contributions to this file may be relicensed under LGPLv2 or later.
 */

#include <stdlib.h>
#include <pthread.h>

#include <urcu/compiler.h>
#include <urcu/arch.h>
#include <urcu/uatomic_arch.h>
#include <urcu/list.h>

#ifdef __cplusplus
extern "C" {
#endif

/*
 * Number of entries in the per-thread defer queue. Must be power of 2.
 */
#define DEFER_QUEUE_SIZE	(1 << 12)
#define DEFER_QUEUE_MASK	(DEFER_QUEUE_SIZE - 1)

/*
 * Typically, data is aligned at least on the architecture size.
 * Use lowest bit to indicate that the current callback is changing.
 * Assumes that (void *)-2L is not used often. Used to encode non-aligned
 * functions and non-aligned data using extra space.
 * We encode the (void *)-2L fct as: -2L, fct, data.
 * We encode the (void *)-2L data as: -2L, fct, data.
 * Here, DQ_FCT_MARK == ~DQ_FCT_BIT. Required for the test order.
 */
#define DQ_FCT_BIT		(1 << 0)
#define DQ_IS_FCT_BIT(x)	((unsigned long)(x) & DQ_FCT_BIT)
#define DQ_SET_FCT_BIT(x)	\
	(x = (void *)((unsigned long)(x) | DQ_FCT_BIT))
#define DQ_CLEAR_FCT_BIT(x)	\
	(x = (void *)((unsigned long)(x) & ~DQ_FCT_BIT))
#define DQ_FCT_MARK		((void *)(~DQ_FCT_BIT))

/*
 * Identify a shared load. A smp_rmc() or smp_mc() should come before the load.
 */
#define _LOAD_SHARED(p)	       ACCESS_ONCE(p)

/*
 * Load a data from shared memory, doing a cache flush if required.
 */
#define LOAD_SHARED(p)			\
	({				\
		smp_rmc();		\
		_LOAD_SHARED(p);	\
	})

/*
 * Identify a shared store. A smp_wmc() or smp_mc() should follow the store.
 */
#define _STORE_SHARED(x, v)	({ ACCESS_ONCE(x) = (v); })

/*
 * Store v into x, where x is located in shared memory. Performs the required
 * cache flush after writing. Returns v.
 */
#define STORE_SHARED(x, v)		\
	({				\
		_STORE_SHARED(x, v);	\
		smp_wmc();		\
		(v);			\
	})

/*
 * This code section can only be included in LGPL 2.1 compatible source code.
 * See below for the function call wrappers which can be used in code meant to
 * be only linked with the Userspace RCU library. This comes with a small
 * performance degradation on the read-side due to the added function calls.
 * This is required to permit relinking with newer versions of the library.
 */

#ifdef DEBUG_RCU
#define rcu_assert(args...)	assert(args)
#else
#define rcu_assert(args...)
#endif

/*
 * defer queue.
 * Contains pointers. Encoded to save space when same callback is often used.
 * When looking up the next item:
 * - if DQ_FCT_BIT is set, set the current callback to DQ_CLEAR_FCT_BIT(ptr)
 *   - next element contains pointer to data.
 * - else if item == DQ_FCT_MARK
 *   - set the current callback to next element ptr
 *   - following next element contains pointer to data.
 * - else current element contains data
 */
struct defer_queue {
	unsigned long head;	/* add element at head */
	void *last_fct_in;	/* last fct pointer encoded */
	unsigned long tail;	/* next element to remove at tail */
	void *last_fct_out;	/* last fct pointer encoded */
	void **q;
	/* registry information */
	unsigned long last_head;
	struct list_head list;	/* list of thread queues */
};

#ifdef __cplusplus 
}
#endif

#endif /* _URCU_DEFER_STATIC_H */
Commit	Line	Data
786ee85b MD	1	#ifndef _URCU_DEFER_STATIC_H
786ee85b MD	2	#define _URCU_DEFER_STATIC_H
90075a50 MD	3
90075a50 MD	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.
90075a50 MD	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
ec4e58a3 MD	35	#include <urcu/compiler.h>
ec4e58a3 MD	36	#include <urcu/arch.h>
48d848c7	37	#include <urcu/uatomic_arch.h>
dbc6128f	38	#include <urcu/list.h>
90075a50	39
36bc70a8 MD	40	#ifdef __cplusplus
	41	extern "C" {
	42	#endif
90075a50 MD	43
90075a50 MD	44	/*
786ee85b	45	* Number of entries in the per-thread defer queue. Must be power of 2.
90075a50	46	*/
786ee85b MD	47	#define DEFER_QUEUE_SIZE (1 << 12)
786ee85b MD	48	#define DEFER_QUEUE_MASK (DEFER_QUEUE_SIZE - 1)
90075a50	49
804b4375 MD	50	/*
	51	* Typically, data is aligned at least on the architecture size.
	52	* Use lowest bit to indicate that the current callback is changing.
	53	* Assumes that (void *)-2L is not used often. Used to encode non-aligned
	54	* functions and non-aligned data using extra space.
	55	* We encode the (void *)-2L fct as: -2L, fct, data.
	56	* We encode the (void *)-2L data as: -2L, fct, data.
	57	* Here, DQ_FCT_MARK == ~DQ_FCT_BIT. Required for the test order.
	58	*/
	59	#define DQ_FCT_BIT (1 << 0)
	60	#define DQ_IS_FCT_BIT(x) ((unsigned long)(x) & DQ_FCT_BIT)
	61	#define DQ_SET_FCT_BIT(x) \
	62	(x = (void *)((unsigned long)(x) \| DQ_FCT_BIT))
	63	#define DQ_CLEAR_FCT_BIT(x) \
	64	(x = (void *)((unsigned long)(x) & ~DQ_FCT_BIT))
	65	#define DQ_FCT_MARK ((void *)(~DQ_FCT_BIT))
	66
90075a50 MD	67	/*
	68	* Identify a shared load. A smp_rmc() or smp_mc() should come before the load.
	69	*/
	70	#define _LOAD_SHARED(p) ACCESS_ONCE(p)
	71
	72	/*
	73	* Load a data from shared memory, doing a cache flush if required.
	74	*/
	75	#define LOAD_SHARED(p) \
	76	({ \
	77	smp_rmc(); \
	78	_LOAD_SHARED(p); \
	79	})
	80
	81	/*
	82	* Identify a shared store. A smp_wmc() or smp_mc() should follow the store.
	83	*/
	84	#define _STORE_SHARED(x, v) ({ ACCESS_ONCE(x) = (v); })
	85
	86	/*
	87	* Store v into x, where x is located in shared memory. Performs the required
	88	* cache flush after writing. Returns v.
	89	*/
	90	#define STORE_SHARED(x, v) \
	91	({ \
	92	_STORE_SHARED(x, v); \
	93	smp_wmc(); \
	94	(v); \
	95	})
	96
	97	/*
	98	* This code section can only be included in LGPL 2.1 compatible source code.
	99	* See below for the function call wrappers which can be used in code meant to
	100	* be only linked with the Userspace RCU library. This comes with a small
	101	* performance degradation on the read-side due to the added function calls.
	102	* This is required to permit relinking with newer versions of the library.
	103	*/
	104
	105	#ifdef DEBUG_RCU
	106	#define rcu_assert(args...) assert(args)
	107	#else
	108	#define rcu_assert(args...)
	109	#endif
	110
804b4375 MD	111	/*
	112	* defer queue.
	113	* Contains pointers. Encoded to save space when same callback is often used.
	114	* When looking up the next item:
	115	* - if DQ_FCT_BIT is set, set the current callback to DQ_CLEAR_FCT_BIT(ptr)
	116	* - next element contains pointer to data.
	117	* - else if item == DQ_FCT_MARK
	118	* - set the current callback to next element ptr
	119	* - following next element contains pointer to data.
	120	* - else current element contains data
	121	*/
786ee85b	122	struct defer_queue {
90075a50	123	unsigned long head; /* add element at head */
804b4375	124	void last_fct_in; / last fct pointer encoded */
90075a50	125	unsigned long tail; /* next element to remove at tail */
804b4375	126	void last_fct_out; / last fct pointer encoded */
90075a50	127	void **q;
dbc6128f MD	128	/* registry information */
	129	unsigned long last_head;
	130	struct list_head list; /* list of thread queues */
90075a50 MD	131	};
90075a50 MD	132
36bc70a8 MD	133	#ifdef __cplusplus
	134	}
	135	#endif
	136
786ee85b	137	#endif /* _URCU_DEFER_STATIC_H */