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 #ifndef _SYS_RR_RW_LOCK_H
27 #define _SYS_RR_RW_LOCK_H
28
29 #pragma ident "%Z%%M% %I% %E% SMI"
30
31 #ifdef __cplusplus
32 extern "C" {
33 #endif
34
35 #include <sys/inttypes.h>
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
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 } rrwlock_t;
61
62 /*
63 * 'tag' is used in reference counting tracking. The
64 * 'tag' must be the same in a rrw_enter() as in its
65 * corresponding rrw_exit().
66 */
67 void rrw_init(rrwlock_t *rrl);
68 void rrw_destroy(rrwlock_t *rrl);
69 void rrw_enter(rrwlock_t *rrl, krw_t rw, void *tag);
70 void rrw_exit(rrwlock_t *rrl, void *tag);
71 boolean_t rrw_held(rrwlock_t *rrl, krw_t rw);
72
73 #define RRW_READ_HELD(x) rrw_held(x, RW_READER)
74 #define RRW_WRITE_HELD(x) rrw_held(x, RW_WRITER)
75
76 #ifdef __cplusplus
77 }
78 #endif
79
80 #endif /* _SYS_RR_RW_LOCK_H */
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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/inttypes.h>
37 #include <sys/zfs_context.h>
38 #include <sys/refcount.h>
39
40 /*
41 * A reader-writer lock implementation that allows re-entrant reads, but
42 * still gives writers priority on "new" reads.
43 *
44 * See rrwlock.c for more details about the implementation.
45 *
46 * Fields of the rrwlock_t structure:
47 * - rr_lock: protects modification and reading of rrwlock_t fields
48 * - rr_cv: cv for waking up readers or waiting writers
49 * - rr_writer: thread id of the current writer
50 * - rr_anon_rount: number of active anonymous readers
51 * - rr_linked_rcount: total number of non-anonymous active readers
53 */
54 typedef struct rrwlock {
55 kmutex_t rr_lock;
56 kcondvar_t rr_cv;
57 kthread_t *rr_writer;
58 refcount_t rr_anon_rcount;
59 refcount_t rr_linked_rcount;
60 boolean_t rr_writer_wanted;
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);
69 void rrw_destroy(rrwlock_t *rrl);
70 void rrw_enter(rrwlock_t *rrl, krw_t rw, void *tag);
71 void rrw_exit(rrwlock_t *rrl, void *tag);
72 boolean_t rrw_held(rrwlock_t *rrl, krw_t rw);
73 void rrw_tsd_destroy(void *arg);
74
75 #define RRW_READ_HELD(x) rrw_held(x, RW_READER)
76 #define RRW_WRITE_HELD(x) rrw_held(x, RW_WRITER)
77
78 #ifdef __cplusplus
79 }
80 #endif
81
82 #endif /* _SYS_RR_RW_LOCK_H */
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