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Diffstat (limited to 'usr/src/boot/sys/sys/_rwlock.h')
| -rw-r--r-- | usr/src/boot/sys/sys/_rwlock.h | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/usr/src/boot/sys/sys/_rwlock.h b/usr/src/boot/sys/sys/_rwlock.h new file mode 100644 index 0000000000..82c911389b --- /dev/null +++ b/usr/src/boot/sys/sys/_rwlock.h @@ -0,0 +1,62 @@ +/*- + * Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $FreeBSD$ + */ + +#ifndef _SYS__RWLOCK_H_ +#define _SYS__RWLOCK_H_ + +#include <machine/param.h> + +/* + * Reader/writer lock. + * + * All reader/writer lock implementations must always have a member + * called rw_lock. Other locking primitive structures are not allowed to + * use this name for their members. + * If this rule needs to change, the bits in the reader/writer lock + * implementation must be modified appropriately. + */ +struct rwlock { + struct lock_object lock_object; + volatile uintptr_t rw_lock; +}; + +/* + * Members of struct rwlock_padalign must mirror members of struct rwlock. + * rwlock_padalign rwlocks can use the rwlock(9) API transparently without + * modification. + * Pad-aligned rwlocks used within structures should generally be the + * first member of the struct. Otherwise, the compiler can generate + * additional padding for the struct to keep a correct alignment for + * the rwlock. + */ +struct rwlock_padalign { + struct lock_object lock_object; + volatile uintptr_t rw_lock; +} __aligned(CACHE_LINE_SIZE); + +#endif /* !_SYS__RWLOCK_H_ */ |