Re: [PATCH] drm/virtio: use %llu format string form atomic64_t

On Monday 19 October 2015 09:34:15 Geert Uytterhoeven wrote:

On Wed, Oct 7, 2015 at 1:23 PM, Arnd Bergmann [off-list ref] wrote:

quoted

static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u)

which truncates the result to 32 bit.

Woops.

See also my unanswered question in "atomic64 on 32-bit vs 64-bit (was:
Re: Add virtio gpu driver.)", which is still valid:
https://lkml.org/lkml/2015/6/28/18

Regarding your question of

Instead of sprinkling casts, is there any good reason why atomic64_read()
and atomic64_t aren't "long long" everywhere, cfr. u64?

I assume the answer is that some (all?) 64-bit architectures intentionally
return 'long' here, in order for atomic_long_read() to return 'long' on
all architectures, given the definitions from
include/asm-generic/atomic-long.h

We would have to either change those, or we have to pick between
atomic_long_* or atomic64_* to have a consistent return type.

	Arnd