Re: [PATCH v3 09/25] openrisc: add optimized atomic operations

[Peter Zijlstra]

On Wed, Feb 22, 2017 at 04:11:38AM +0900, Stafford Horne wrote:
> +#define atomic_add_return    atomic_add_return
> +#define atomic_sub_return    atomic_sub_return
> +#define atomic_fetch_add     atomic_fetch_add
> +#define atomic_fetch_sub     atomic_fetch_sub
> +#define atomic_fetch_and     atomic_fetch_and
> +#define atomic_fetch_or              atomic_fetch_or
> +#define atomic_fetch_xor     atomic_fetch_xor
> +#define atomic_and   atomic_and
> +#define atomic_or    atomic_or
> +#define atomic_xor   atomic_xor
> +

It would be good to also implement __atomic_add_unless().

Something like so, if I got your asm right..

static inline int __atomic_add_unless(atomic_t *v, int a, int u)
{
        int old, tmp;

        __asm__ __volatile__(
                "1:     l.lwa %0, 0(%2)         \n"
                "       l.sfeq %0, %4           \n"
                "       l.bf 2f                 \n"
                "        l.nop                  \n"
                "       l.add %1, %0, %3        \n"
                "       l.swa 0(%2), %1         \n"
                "       l.bnf 1b                \n"
                "2:      l.nop                  \n"
                : "=&r"(old), "=&r" (tmp)
                : "r"(&v->counter), "r"(a), "r"(u)
                : "cc", "memory");

        return old;
}