1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 /* 26 * Copyright (c) 2012 by Delphix. All rights reserved. 27 */ 28 29 #ifndef _SYS_RR_RW_LOCK_H 30 #define _SYS_RR_RW_LOCK_H 31 32 #ifdef __cplusplus 33 extern "C" { 34 #endif 35 36 #include <sys/zfs_context.h> 37 #include <sys/refcount.h> 38 39 /* 40 * A reader-writer lock implementation that allows re-entrant reads, but 41 * still gives writers priority on "new" reads. 42 * 43 * See rrwlock.c for more details about the implementation. 44 * 45 * Fields of the rrwlock_t structure: 46 * - rr_lock: protects modification and reading of rrwlock_t fields 47 * - rr_cv: cv for waking up readers or waiting writers 48 * - rr_writer: thread id of the current writer 49 * - rr_anon_rount: number of active anonymous readers 50 * - rr_linked_rcount: total number of non-anonymous active readers 51 * - rr_writer_wanted: a writer wants the lock 52 */ 53 typedef struct rrwlock { 54 kmutex_t rr_lock; 55 kcondvar_t rr_cv; 56 kthread_t *rr_writer; 57 refcount_t rr_anon_rcount; 58 refcount_t rr_linked_rcount; 59 boolean_t rr_writer_wanted; 60 boolean_t rr_track_all; 61 } rrwlock_t; 62 63 /* 64 * 'tag' is used in reference counting tracking. The 65 * 'tag' must be the same in a rrw_enter() as in its 66 * corresponding rrw_exit(). 67 */ 68 void rrw_init(rrwlock_t *rrl, boolean_t track_all); 69 void rrw_destroy(rrwlock_t *rrl); 70 void rrw_enter(rrwlock_t *rrl, krw_t rw, void *tag); 71 void rrw_enter_read(rrwlock_t *rrl, void *tag); 72 void rrw_enter_read_prio(rrwlock_t *rrl, void *tag); 73 void rrw_enter_write(rrwlock_t *rrl); 74 void rrw_exit(rrwlock_t *rrl, void *tag); 75 boolean_t rrw_held(rrwlock_t *rrl, krw_t rw); 76 void rrw_tsd_destroy(void *arg); 77 78 #define RRW_READ_HELD(x) rrw_held(x, RW_READER) 79 #define RRW_WRITE_HELD(x) rrw_held(x, RW_WRITER) 80 #define RRW_LOCK_HELD(x) \ 81 (rrw_held(x, RW_WRITER) || rrw_held(x, RW_READER)) 82 83 /* 84 * A reader-mostly lock implementation, tuning above reader-writer locks 85 * for hightly parallel read acquisitions, pessimizing write acquisitions. 86 * 87 * This should be a prime number. See comment in rrwlock.c near 88 * RRM_TD_LOCK() for details. 89 */ 90 #define RRM_NUM_LOCKS 17 91 typedef struct rrmlock { 92 rrwlock_t locks[RRM_NUM_LOCKS]; 93 } rrmlock_t; 94 95 void rrm_init(rrmlock_t *rrl, boolean_t track_all); 96 void rrm_destroy(rrmlock_t *rrl); 97 void rrm_enter(rrmlock_t *rrl, krw_t rw, void *tag); 98 void rrm_enter_read(rrmlock_t *rrl, void *tag); 99 void rrm_enter_write(rrmlock_t *rrl); 100 void rrm_exit(rrmlock_t *rrl, void *tag); 101 boolean_t rrm_held(rrmlock_t *rrl, krw_t rw); 102 103 #define RRM_READ_HELD(x) rrm_held(x, RW_READER) 104 #define RRM_WRITE_HELD(x) rrm_held(x, RW_WRITER) 105 #define RRM_LOCK_HELD(x) \ 106 (rrm_held(x, RW_WRITER) || rrm_held(x, RW_READER)) 107 108 #ifdef __cplusplus 109 } 110 #endif 111 112 #endif /* _SYS_RR_RW_LOCK_H */ 113