On Monday 19 October 2015 09:34:15 Geert Uytterhoeven wrote:
On Wed, Oct 7, 2015 at 1:23 PM, Arnd Bergmann arnd@arndb.de wrote:
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