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/*
* 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 2009 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#ifndef _SYS_CONDVAR_IMPL_H
#define _SYS_CONDVAR_IMPL_H
/*
* Implementation-private definitions for condition variables
*/
#ifndef _ASM
#include <sys/types.h>
#include <sys/thread.h>
#endif /* _ASM */
#ifdef __cplusplus
extern "C" {
#endif
#ifndef _ASM
/*
* Condtion variables.
*/
typedef struct _condvar_impl {
ushort_t cv_waiters;
} condvar_impl_t;
#define CV_HAS_WAITERS(cvp) (((condvar_impl_t *)(cvp))->cv_waiters != 0)
#endif /* _ASM */
/*
* The cvwaitlock_t structure and associated macros provide an implementation
* of a locking mechanism that allows recursion on the reader lock without
* danger of a pending write lock elsewhere being able to cause a deadlock.
* The provision for supporting recursion is necessary for use with the
* netinfo (neti) kernel module when processing network data.
*
* Support for recursion (giving precedence to readers and allowing them
* to enter even when a write is blocked) can result in write starvation.
* There is no priority inheritence for this locking interface.
*/
typedef struct cvwaitlock_s {
kmutex_t cvw_lock;
kcondvar_t cvw_waiter;
int cvw_refcnt;
} cvwaitlock_t;
#define CVW_INIT(_c) { \
mutex_init(&(_c)->cvw_lock, NULL, MUTEX_DRIVER, NULL); \
cv_init(&(_c)->cvw_waiter, NULL, CV_DRIVER, NULL); \
(_c)->cvw_refcnt = 0; \
}
#define CVW_ENTER_READ(_c) { \
mutex_enter(&(_c)->cvw_lock); \
while ((_c)->cvw_refcnt < 0) \
cv_wait(&((_c)->cvw_waiter), &(_c)->cvw_lock); \
(_c)->cvw_refcnt++; \
mutex_exit(&(_c)->cvw_lock); \
}
#define CVW_ENTER_WRITE(_c) { \
mutex_enter(&(_c)->cvw_lock); \
while ((_c)->cvw_refcnt != 0) \
cv_wait(&((_c)->cvw_waiter), &(_c)->cvw_lock); \
(_c)->cvw_refcnt = -1; \
mutex_exit(&(_c)->cvw_lock); \
}
#define CVW_EXIT_READ(_c) { \
mutex_enter(&(_c)->cvw_lock); \
ASSERT((_c)->cvw_refcnt > 0); \
if ((--((_c)->cvw_refcnt)) == 0) \
cv_broadcast(&(_c)->cvw_waiter); \
mutex_exit(&(_c)->cvw_lock); \
}
#define CVW_EXIT_WRITE(_c) { \
mutex_enter(&(_c)->cvw_lock); \
ASSERT((_c)->cvw_refcnt == -1); \
(_c)->cvw_refcnt = 0; \
cv_broadcast(&(_c)->cvw_waiter); \
mutex_exit(&(_c)->cvw_lock); \
}
#define CVW_WRITE_TO_READ(_c) { \
mutex_enter(&(_c)->cvw_lock); \
ASSERT((_c)->cvw_refcnt == -1); \
(_c)->cvw_refcnt = 1; \
cv_broadcast(&(_c)->cvw_waiter); \
mutex_exit(&(_c)->cvw_lock); \
}
#define CVW_DESTROY(_c) { \
mutex_destroy(&(_c)->cvw_lock); \
cv_destroy(&(_c)->cvw_waiter); \
}
#ifdef __cplusplus
}
#endif
#endif /* _SYS_CONDVAR_IMPL_H */
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