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.
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.
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]
22 * Copyright 2007 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
26 * Copyright (c) 2012 by Delphix. All rights reserved.
29 #ifndef _SYS_RR_RW_LOCK_H
30 #define _SYS_RR_RW_LOCK_H
38 #include <sys/inttypes.h>
39 #include <sys/zfs_context.h>
40 #include <sys/refcount.h>
43 * A reader-writer lock implementation that allows re-entrant reads, but
44 * still gives writers priority on "new" reads.
46 * See rrwlock.c for more details about the implementation.
48 * Fields of the rrwlock_t structure:
49 * - rr_lock: protects modification and reading of rrwlock_t fields
50 * - rr_cv: cv for waking up readers or waiting writers
51 * - rr_writer: thread id of the current writer
52 * - rr_anon_rount: number of active anonymous readers
53 * - rr_linked_rcount: total number of non-anonymous active readers
54 * - rr_writer_wanted: a writer wants the lock
56 typedef struct rrwlock
{
60 refcount_t rr_anon_rcount
;
61 refcount_t rr_linked_rcount
;
62 boolean_t rr_writer_wanted
;
63 boolean_t rr_track_all
;
67 * 'tag' is used in reference counting tracking. The
68 * 'tag' must be the same in a rrw_enter() as in its
69 * corresponding rrw_exit().
71 void rrw_init(rrwlock_t
*rrl
, boolean_t track_all
);
72 void rrw_destroy(rrwlock_t
*rrl
);
73 void rrw_enter(rrwlock_t
*rrl
, krw_t rw
, void *tag
);
74 void rrw_enter_read(rrwlock_t
*rrl
, void *tag
);
75 void rrw_enter_write(rrwlock_t
*rrl
);
76 void rrw_exit(rrwlock_t
*rrl
, void *tag
);
77 boolean_t
rrw_held(rrwlock_t
*rrl
, krw_t rw
);
78 void rrw_tsd_destroy(void *arg
);
80 #define RRW_READ_HELD(x) rrw_held(x, RW_READER)
81 #define RRW_WRITE_HELD(x) rrw_held(x, RW_WRITER)
82 #define RRW_LOCK_HELD(x) \
83 (rrw_held(x, RW_WRITER) || rrw_held(x, RW_READER))
89 #endif /* _SYS_RR_RW_LOCK_H */