Hi...
On Thu, Dec 15, 2011 at 11:05, Parmenides <mobile.parmenides@xxxxxxxxx> wrote:
> The xadd will store v->counter into i, and store v->counter+i into
> v->counter. I wonder why we bother to obtain v->counter atomically. I
> try to modify the asm with the following code:
>
> static __inline__ int atomic_add_return(int i, atomic_t *v)
> {
> __asm__ __volatile__(
> LOCK "addl %1, %0;"
> : "m"(v->counter)
> : "=r"(i), "m"(v->counter));
> return v->counter;
> }
>
> Does my code may cause some problems concerning atomic operation?
Wikipedia explains about it:
http://en.wikipedia.org/wiki/Fetch-and-add
Although I am not also so clear, it says something related to
returning original value memory location. Maybe that's needed since we
pass v by reference, not by value
--
regards,
Mulyadi Santosa
Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com
_______________________________________________
Kernelnewbies mailing list
Kernelnewbies@xxxxxxxxxxxxxxxxx
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
