On Mon, Jul 27, 2020 at 04:23:03PM +0100, Vincent Donnefort wrote:
> For 32-bit architectures, both min_vruntime and last_update_time are using
> similar access. This patch is simply an attempt to unify their usage by
> introducing two macros to rely on when accessing those. At the same time, it
> brings a comment regarding the barriers usage, as per the kernel policy. So
> overall this is just a clean-up without any functional changes.
Ah, I though there was perhaps the idea to make use of armv7-lpae
instructions.
Aside of that, I think we need to spend a little time bike-shedding the
API/naming here:
> +# define u64_32read(val, copy) (val)
> +# define u64_32read_set_copy(val, copy) do { } while (0)
How about something like:
#ifdef CONFIG_64BIT
#define DEFINE_U64_U32(name) u64 name
#define u64_u32_load(name) name
#define u64_u32_store(name, val)name = val
#else
#define DEFINE_U64_U32(name) \
struct { \
u64 name; \
u64 name##_copy; \
}
#define u64_u32_load(name) \
({ \
u64 val, copy; \
do { \
val = name; \
smb_rmb(); \
copy = name##_copy; \
} while (val != copy); \
val;
})
#define u64_u32_store(name, val) \
do { \
typeof(val) __val = (val); \
name = __val; \
smp_wmb(); \
name##_copy = __val; \
} while (0)
#endif
