f4043145f2
It's not sufficient nor required to use the vnode interlock when checking if we are going to drop the last use count as the code in vputx() uses refcount (atomic) operations for both checking and decrementing the use code. Apply the same method to vn_rele_async(). While here, remove vn_rele_inactive(), a wrapper around vrele() that didn't add any value. Also, the change required making vfs_refcount_release_if_not_last() public. I've made vfs_refcount_acquire_if_not_zero() public as well. They are in sys/refcount.h now. While making the move I've dropped the vfs_ prefix. Reviewed by: mjg MFC after: 2 weeks Sponsored by: Panzura Differential Revision: https://reviews.freebsd.org/D14869
111 lines
2.8 KiB
C
111 lines
2.8 KiB
C
/*-
|
|
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
|
|
*
|
|
* Copyright (c) 2005 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_REFCOUNT_H__
|
|
#define __SYS_REFCOUNT_H__
|
|
|
|
#include <sys/limits.h>
|
|
#include <machine/atomic.h>
|
|
|
|
#ifdef _KERNEL
|
|
#include <sys/systm.h>
|
|
#else
|
|
#define KASSERT(exp, msg) /* */
|
|
#endif
|
|
|
|
static __inline void
|
|
refcount_init(volatile u_int *count, u_int value)
|
|
{
|
|
|
|
*count = value;
|
|
}
|
|
|
|
static __inline void
|
|
refcount_acquire(volatile u_int *count)
|
|
{
|
|
|
|
KASSERT(*count < UINT_MAX, ("refcount %p overflowed", count));
|
|
atomic_add_int(count, 1);
|
|
}
|
|
|
|
static __inline int
|
|
refcount_release(volatile u_int *count)
|
|
{
|
|
u_int old;
|
|
|
|
atomic_thread_fence_rel();
|
|
old = atomic_fetchadd_int(count, -1);
|
|
KASSERT(old > 0, ("negative refcount %p", count));
|
|
if (old > 1)
|
|
return (0);
|
|
|
|
/*
|
|
* Last reference. Signal the user to call the destructor.
|
|
*
|
|
* Ensure that the destructor sees all updates. The fence_rel
|
|
* at the start of the function synchronized with this fence.
|
|
*/
|
|
atomic_thread_fence_acq();
|
|
return (1);
|
|
}
|
|
|
|
/*
|
|
* A temporary hack until refcount_* APIs are sorted out.
|
|
*/
|
|
static __inline int
|
|
refcount_acquire_if_not_zero(volatile u_int *count)
|
|
{
|
|
u_int old;
|
|
|
|
old = *count;
|
|
for (;;) {
|
|
if (old == 0)
|
|
return (0);
|
|
if (atomic_fcmpset_int(count, &old, old + 1))
|
|
return (1);
|
|
}
|
|
}
|
|
|
|
static __inline int
|
|
refcount_release_if_not_last(volatile u_int *count)
|
|
{
|
|
u_int old;
|
|
|
|
old = *count;
|
|
for (;;) {
|
|
if (old == 1)
|
|
return (0);
|
|
if (atomic_fcmpset_int(count, &old, old - 1))
|
|
return (1);
|
|
}
|
|
}
|
|
|
|
#endif /* ! __SYS_REFCOUNT_H__ */
|