diff options
Diffstat (limited to 'uts/common/fs/zfs/sys/rrwlock.h')
| -rw-r--r-- | uts/common/fs/zfs/sys/rrwlock.h | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/uts/common/fs/zfs/sys/rrwlock.h b/uts/common/fs/zfs/sys/rrwlock.h new file mode 100644 index 000000000000..19a43c97fc3c --- /dev/null +++ b/uts/common/fs/zfs/sys/rrwlock.h @@ -0,0 +1,80 @@ +/* + * CDDL HEADER START + * + * The contents of this file are subject to the terms of the + * Common Development and Distribution License (the "License"). + * You may not use this file except in compliance with the License. + * + * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE + * or http://www.opensolaris.org/os/licensing. + * See the License for the specific language governing permissions + * and limitations under the License. + * + * When distributing Covered Code, include this CDDL HEADER in each + * file and include the License file at usr/src/OPENSOLARIS.LICENSE. + * If applicable, add the following below this CDDL HEADER, with the + * fields enclosed by brackets "[]" replaced with your own identifying + * information: Portions Copyright [yyyy] [name of copyright owner] + * + * CDDL HEADER END + */ +/* + * Copyright 2007 Sun Microsystems, Inc. All rights reserved. + * Use is subject to license terms. + */ + +#ifndef _SYS_RR_RW_LOCK_H +#define _SYS_RR_RW_LOCK_H + +#pragma ident "%Z%%M% %I% %E% SMI" + +#ifdef __cplusplus +extern "C" { +#endif + +#include <sys/inttypes.h> +#include <sys/zfs_context.h> +#include <sys/refcount.h> + +/* + * A reader-writer lock implementation that allows re-entrant reads, but + * still gives writers priority on "new" reads. + * + * See rrwlock.c for more details about the implementation. + * + * Fields of the rrwlock_t structure: + * - rr_lock: protects modification and reading of rrwlock_t fields + * - rr_cv: cv for waking up readers or waiting writers + * - rr_writer: thread id of the current writer + * - rr_anon_rount: number of active anonymous readers + * - rr_linked_rcount: total number of non-anonymous active readers + * - rr_writer_wanted: a writer wants the lock + */ +typedef struct rrwlock { + kmutex_t rr_lock; + kcondvar_t rr_cv; + kthread_t *rr_writer; + refcount_t rr_anon_rcount; + refcount_t rr_linked_rcount; + boolean_t rr_writer_wanted; +} rrwlock_t; + +/* + * 'tag' is used in reference counting tracking. The + * 'tag' must be the same in a rrw_enter() as in its + * corresponding rrw_exit(). + */ +void rrw_init(rrwlock_t *rrl); +void rrw_destroy(rrwlock_t *rrl); +void rrw_enter(rrwlock_t *rrl, krw_t rw, void *tag); +void rrw_exit(rrwlock_t *rrl, void *tag); +boolean_t rrw_held(rrwlock_t *rrl, krw_t rw); + +#define RRW_READ_HELD(x) rrw_held(x, RW_READER) +#define RRW_WRITE_HELD(x) rrw_held(x, RW_WRITER) + +#ifdef __cplusplus +} +#endif + +#endif /* _SYS_RR_RW_LOCK_H */ |