> On Apr 14, 2019, at 3:14 AM, Shyam Saini <shyam.saini@xxxxxxxxxxxxxxxxxxxx> wrote: > > Currently, there are 3 different macros, namely sizeof_field, SIZEOF_FIELD > and FIELD_SIZEOF which are used to calculate the size of a member of > structure, so to bring uniformity in entire kernel source tree lets use > FIELD_SIZEOF and replace all occurrences of other two macros with this. > > For this purpose, redefine FIELD_SIZEOF in include/linux/stddef.h and > tools/testing/selftests/bpf/bpf_util.h and remove its defination from > include/linux/kernel.h > --- a/include/linux/stddef.h > +++ b/include/linux/stddef.h > @@ -20,6 +20,15 @@ enum { > #endif > > /** > + * FIELD_SIZEOF - get the size of a struct's field > + * @t: the target struct > + * @f: the target struct's field > + * Return: the size of @f in the struct definition without having a > + * declared instance of @t. > + */ > +#define FIELD_SIZEOF(t, f) (sizeof(((t *)0)->f)) > + > +/** > * sizeof_field(TYPE, MEMBER) > * > * @TYPE: The structure containing the field of interest > @@ -34,6 +43,6 @@ enum { > * @MEMBER: The member within the structure to get the end offset of > */ > #define offsetofend(TYPE, MEMBER) \ > - (offsetof(TYPE, MEMBER) + sizeof_field(TYPE, MEMBER)) > + (offsetof(TYPE, MEMBER) + FIELD_SIZEOF(TYPE, MEMBER)) If you're doing this, why are you leaving the definition of sizeof_field() in stddef.h untouched? Given the way this has worked historically, if you are leaving it in place for source compatibility reasons, shouldn't it be redefined in terms of FIELD_SIZEOF(), e.g.: #define sizeof_field(TYPE, MEMBER) FIELD_SIZEOF(TYPE, MEMBER)