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Check for negative reference count.

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Reviewed by:	des
This commit is contained in:
Pawel Jakub Dawidek 2008-07-23 11:17:46 +00:00
parent 138ddff935
commit a16ab3b093
1 changed files with 10 additions and 1 deletions
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11
sys/sys/refcount.h
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@ -32,6 +32,12 @@
#ifndef __SYS_REFCOUNT_H__
#define __SYS_REFCOUNT_H__
#ifdef _KERNEL
#include <sys/systm.h>
#else
#include <assert.h>
#define KASSERT(exp, msg) assert(exp)
#endif
#include <machine/atomic.h>
static __inline void
@ -51,9 +57,12 @@ refcount_acquire(volatile u_int *count)
static __inline int
refcount_release(volatile u_int *count)
{
u_int old;
/* XXX: Should this have a rel membar? */
return (atomic_fetchadd_int(count, -1) == 1);
old = atomic_fetchadd_int(count, -1);
KASSERT(old > 0, ("negative refcount %p", count));
return (old == 1);
}
#endif /* ! __SYS_REFCOUNT_H__ */