[urcu.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>


/*
 * 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 */
};

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