On Jun 11, 2019, at 3:09 PM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > On Tue, 11 Jun 2019 15:00:10 -0600 Andreas Dilger <adilger@xxxxxxxxx> wrote: > >>>> to FIELD_SIZEOF >>> >>> As Alexey has pointed out, C structs and unions don't have fields - >>> they have members. So this is an opportunity to switch everything to >>> a new member_sizeof(). >>> >>> What do people think of that and how does this impact the patch footprint? >> >> I did a check, and FIELD_SIZEOF() is used about 350x, while sizeof_field() >> is about 30x, and SIZEOF_FIELD() is only about 5x. > > Erk. Sorry, I should have grepped. > >> That said, I'm much more in favour of "sizeof_field()" or "sizeof_member()" >> than FIELD_SIZEOF(). Not only does that better match "offsetof()", with >> which it is closely related, but is also closer to the original "sizeof()". >> >> Since this is a rather trivial change, it can be split into a number of >> patches to get approval/landing via subsystem maintainers, and there is no >> huge urgency to remove the original macros until the users are gone. It >> would make sense to remove SIZEOF_FIELD() and sizeof_field() quickly so >> they don't gain more users, and the remaining FIELD_SIZEOF() users can be >> whittled away as the patches come through the maintainer trees. > > In that case I'd say let's live with FIELD_SIZEOF() and remove > sizeof_field() and SIZEOF_FIELD(). The real question is whether we want to live with a sub-standard macro for the next 20 years rather than taking the opportunity to clean it up now? > I'm a bit surprised that the FIELD_SIZEOF() definition ends up in > stddef.h rather than in kernel.h where such things are normally > defined. Why is that? Cheers, Andreas
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