1*5326Sek110237 /* 2*5326Sek110237 * CDDL HEADER START 3*5326Sek110237 * 4*5326Sek110237 * The contents of this file are subject to the terms of the 5*5326Sek110237 * Common Development and Distribution License (the "License"). 6*5326Sek110237 * You may not use this file except in compliance with the License. 7*5326Sek110237 * 8*5326Sek110237 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9*5326Sek110237 * or http://www.opensolaris.org/os/licensing. 10*5326Sek110237 * See the License for the specific language governing permissions 11*5326Sek110237 * and limitations under the License. 12*5326Sek110237 * 13*5326Sek110237 * When distributing Covered Code, include this CDDL HEADER in each 14*5326Sek110237 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15*5326Sek110237 * If applicable, add the following below this CDDL HEADER, with the 16*5326Sek110237 * fields enclosed by brackets "[]" replaced with your own identifying 17*5326Sek110237 * information: Portions Copyright [yyyy] [name of copyright owner] 18*5326Sek110237 * 19*5326Sek110237 * CDDL HEADER END 20*5326Sek110237 */ 21*5326Sek110237 /* 22*5326Sek110237 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 23*5326Sek110237 * Use is subject to license terms. 24*5326Sek110237 */ 25*5326Sek110237 26*5326Sek110237 #ifndef _SYS_RR_RW_LOCK_H 27*5326Sek110237 #define _SYS_RR_RW_LOCK_H 28*5326Sek110237 29*5326Sek110237 #pragma ident "%Z%%M% %I% %E% SMI" 30*5326Sek110237 31*5326Sek110237 #ifdef __cplusplus 32*5326Sek110237 extern "C" { 33*5326Sek110237 #endif 34*5326Sek110237 35*5326Sek110237 #include <sys/inttypes.h> 36*5326Sek110237 #include <sys/zfs_context.h> 37*5326Sek110237 #include <sys/refcount.h> 38*5326Sek110237 39*5326Sek110237 /* 40*5326Sek110237 * A reader-writer lock implementation that allows re-entrant reads, but 41*5326Sek110237 * still gives writers priority on "new" reads. 42*5326Sek110237 * 43*5326Sek110237 * See rrwlock.c for more details about the implementation. 44*5326Sek110237 * 45*5326Sek110237 * Fields of the rrwlock_t structure: 46*5326Sek110237 * - rr_lock: protects modification and reading of rrwlock_t fields 47*5326Sek110237 * - rr_cv: cv for waking up readers or waiting writers 48*5326Sek110237 * - rr_writer: thread id of the current writer 49*5326Sek110237 * - rr_anon_rount: number of active anonymous readers 50*5326Sek110237 * - rr_linked_rcount: total number of non-anonymous active readers 51*5326Sek110237 * - rr_writer_wanted: a writer wants the lock 52*5326Sek110237 */ 53*5326Sek110237 typedef struct rrwlock { 54*5326Sek110237 kmutex_t rr_lock; 55*5326Sek110237 kcondvar_t rr_cv; 56*5326Sek110237 kthread_t *rr_writer; 57*5326Sek110237 refcount_t rr_anon_rcount; 58*5326Sek110237 refcount_t rr_linked_rcount; 59*5326Sek110237 boolean_t rr_writer_wanted; 60*5326Sek110237 } rrwlock_t; 61*5326Sek110237 62*5326Sek110237 /* 63*5326Sek110237 * 'tag' is used in reference counting tracking. The 64*5326Sek110237 * 'tag' must be the same in a rrw_enter() as in its 65*5326Sek110237 * corresponding rrw_exit(). 66*5326Sek110237 */ 67*5326Sek110237 void rrw_init(rrwlock_t *rrl); 68*5326Sek110237 void rrw_destroy(rrwlock_t *rrl); 69*5326Sek110237 void rrw_enter(rrwlock_t *rrl, krw_t rw, void *tag); 70*5326Sek110237 void rrw_exit(rrwlock_t *rrl, void *tag); 71*5326Sek110237 boolean_t rrw_held(rrwlock_t *rrl, krw_t rw); 72*5326Sek110237 73*5326Sek110237 #define RRW_READ_HELD(x) rrw_held(x, RW_READER) 74*5326Sek110237 #define RRW_WRITE_HELD(x) rrw_held(x, RW_WRITER) 75*5326Sek110237 76*5326Sek110237 #ifdef __cplusplus 77*5326Sek110237 } 78*5326Sek110237 #endif 79*5326Sek110237 80*5326Sek110237 #endif /* _SYS_RR_RW_LOCK_H */ 81