Re: [Xen-devel] [PATCH 4/4] xen: Introduce a xmemdup_bytes() helper

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 23/03/2020 08:38, Jan Beulich wrote:
> On 21.03.2020 23:19, Julien Grall wrote:
>> On Fri, 20 Mar 2020 at 21:26, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> 
>> wrote:
>>> --- a/xen/include/xen/xmalloc.h
>>> +++ b/xen/include/xen/xmalloc.h
>>> @@ -51,6 +51,17 @@
>>>  #define xmalloc_bytes(_bytes) _xmalloc(_bytes, SMP_CACHE_BYTES)
>>>  #define xzalloc_bytes(_bytes) _xzalloc(_bytes, SMP_CACHE_BYTES)
>>>
>>> +/* Allocate untyped storage and copying an existing instance. */
>>> +#define xmemdup_bytes(_src, _nr)                \
>>> +    ({                                          \
>>> +        unsigned long nr_ = (_nr);              \
>>> +        void *dst_ = xmalloc_bytes(nr_);        \
>> The nr_ vs _nr is really confusing to read. Could you re-implement the
>> function as a static inline?
> And even if that wouldn't work out - what's the point of having
> macro argument names with leading underscores?

Consistency with all the other code in this file.

>  This isn't any
> better standard-wise (afaict) than other uses of leading
> underscores for identifiers which aren't CU-scope.

It is a parameter describing textural replacement within the body. 
There is 0 interaction with external namespacing standards.

~Andrew