On Fri, Jul 8, 2016 at 11:02 AM, Peter Zijlstra <[email protected]> wrote:
> On Fri, Jul 08, 2016 at 01:20:08AM +0300, Alexey Dobriyan wrote:
>> Currently WRITE_ONCE is used as if it returns void. Let's codify this
>> before somebody tries to be smarter than necessary.
>>
>> Signed-off-by: Alexey Dobriyan <[email protected]>
>> ---
>>
>> include/linux/compiler.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> --- a/include/linux/compiler.h
>> +++ b/include/linux/compiler.h
>> @@ -301,7 +301,7 @@ static __always_inline void __write_once_size(volatile
>> void *p, void *res, int s
>> union { typeof(x) __val; char __c[1]; } __u = \
>> { .__val = (__force typeof(x)) (val) }; \
>> __write_once_size(&(x), __u.__c, sizeof(x)); \
>> - __u.__val; \
>> + (void)0; \
>> })
>
> Why then still use the statement expression? Would it not make more
> sense to change it into the regular do { } while (0) form if you want to
> remove the return semantics?
Statement expression is better because it is an expression
so you can write code like
foo ? WRITE_ONCE(a, 0) : WRITE_ONCE(b, 0)
or
for (... ; ... ; WRITE_ONCE(a, 0), x++)
"do {} while (0)" should be deprecated really.
