util/u_atomic: Fix the unlocked implementation.

It was totally broken:

- p_atomic_dec_zero() was returning the negation of the expected value

- p_atomic_inc_return()/p_atomic_dec_return() was
  post-incrementing/decrementing, hence returning the old value instead
  of the new

- p_atomic_cmpxchg() was returning the new value on success, instead of
  the old

It is clear this never used in the past. I wonder if it wouldn't be better to
yank it altogether.

Reviewed-by: Matt Turner <mattst88@gmail.com>
This commit is contained in:
José Fonseca 2014-11-25 14:25:28 +00:00 committed by Matt Turner
parent ff80b92a58
commit a5299e9e1c

View file

@ -57,12 +57,12 @@
#define p_atomic_set(_v, _i) (*(_v) = (_i))
#define p_atomic_read(_v) (*(_v))
#define p_atomic_dec_zero(_v) ((bool) --(*(_v)))
#define p_atomic_inc(_v) ((void) (*(_v))++)
#define p_atomic_dec(_v) ((void) (*(_v))--)
#define p_atomic_inc_return(_v) ((*(_v))++)
#define p_atomic_dec_return(_v) ((*(_v))--)
#define p_atomic_cmpxchg(_v, old, _new) (*(_v) == old ? *(_v) = (_new) : *(_v))
#define p_atomic_dec_zero(_v) (p_atomic_dec_return(_v) == 0)
#define p_atomic_inc(_v) ((void) p_atomic_inc_return(_v))
#define p_atomic_dec(_v) ((void) p_atomic_dec_return(_v))
#define p_atomic_inc_return(_v) (++(*(_v)))
#define p_atomic_dec_return(_v) (--(*(_v)))
#define p_atomic_cmpxchg(_v, _old, _new) (*(_v) == (_old) ? (*(_v) = (_new), (_old)) : *(_v))
#endif