>Ian Appru wrote:
>> While atomic increment/decrements (using cas) are suffiently well documented
>> for me to be pretty
confident in my implementation I would apreciate any input for an atomic
conditional increment.
>
>I'd expect the following to work on OpenSolaris:
>
>#include <atomic.h>
>
>int atomic_conditional_increment(int *target)
>{
> for (;;) {
> int old = *target;
> if (old == 0)
> return 0;
>
> if (atomic_cas_uint((uint_t *) target, old, old + 1) == old)
> return old + 1;
> }
>}
You will certainly need a membar before reading *target.
(If not, it can happen that one thread continuously sees "0" while
another CPU runs away incrementing the counter.
(And you function has a bug in that it will not always update a non-zero
target)
Casper
_______________________________________________
opensolaris-discuss mailing list
[email protected]
