ATOMIC_DEC(9F) Kernel Functions for Drivers ATOMIC_DEC(9F)


NAME


atomic_dec, atomic_dec_8, atomic_dec_uchar, atomic_dec_16,
atomic_dec_ushort, atomic_dec_32, atomic_dec_uint, atomic_dec_ulong,
atomic_dec_64, atomic_dec_ptr, atomic_dec_8_nv, atomic_dec_uchar_nv,
atomic_dec_16_nv, atomic_dec_ushort_nv, atomic_dec_32_nv,
atomic_dec_uint_nv, atomic_dec_ulong_nv, atomic_dec_64_nv,
atomic_dec_ptr_nv - atomic decrement operations

SYNOPSIS


#include <sys/atomic.h>

void atomic_dec_8(volatile uint8_t *target);


void atomic_dec_uchar(volatile uchar_t *target);


void atomic_dec_16(volatile uint16_t *target);


void atomic_dec_ushort(volatile ushort_t *target);


void atomic_dec_32(volatile uint32_t *target);


void atomic_dec_uint(volatile uint_t *target);


void atomic_dec_ulong(volatile ulong_t *target);


void atomic_dec_64(volatile uint64_t *target);


void atomic_dec_ptr(volatile void *target);


uint8_t atomic_dec_8_nv(volatile uint8_t *target);


uchar_t atomic_dec_uchar_nv(volatile uchar_t *target);


uint16_t atomic_dec_16_nv(volatile uint16_t *target);


ushort_t atomic_dec_ushort_nv(volatile ushort_t *target);


uint32_t atomic_dec_32_nv(volatile uint32_t *target);


uint_t atomic_dec_uint_nv(volatile uint_t *target);


ulong_t atomic_dec_ulong_nv(volatile ulong_t *target);


uint64_t atomic_dec_64_nv(volatile uint64_t *target);


void *atomic_dec_ptr_nv(volatile void *target);


DESCRIPTION


These functions enable the decrementing (by one) of the value stored in
target to occur in an atomic manner.

RETURN VALUES


The *_nv() variants of these functions return the new value of target.

ERRORS


No errors are defined.

CONTEXT


These functions can be called from user, interrupt, or kernel context.

ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Committed |
+--------------------+-----------------+

SEE ALSO


atomic_add(9F), atomic_and(9F), atomic_bits(9F), atomic_cas(9F),
atomic_inc(9F), atomic_or(9F), atomic_swap(9F), membar_ops(9F),
attributes(5), atomic_ops(3C)

NOTES


The *_nv() variants are substantially more expensive on some platforms
than the versions that do not return values. Do not use them unless you
need to know the new value atomically (for example, when decrementing a
reference count and checking whether it went to zero).


January 16, 2006 ATOMIC_DEC(9F)