Date: Tue, 24 Sep 2019 09:22:10 -0700 From: Kees Cook <keescook@...omium.org> To: Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@...el.com> Cc: pankaj.bharadiya@...il.com, andriy.shevchenko@...ux.intel.com, kernel-hardening@...ts.openwall.com, akpm@...ux-foundation.org, mayhs11saini@...il.com, linux-kernel@...r.kernel.org Subject: Re: [PATCH 1/5] linux/kernel.h: Add sizeof_member macro On Tue, Sep 24, 2019 at 04:28:35PM +0530, Pankaj Bharadiya wrote: > At present we have 3 different macros to calculate the size of a > member of a struct: > - SIZEOF_FIELD > - FIELD_SIZEOF > - sizeof_field > > To bring uniformity in entire kernel source tree let's add > sizeof_member macro. > > Replace all occurrences of above 3 macro's with sizeof_member in > future patches. > > Signed-off-by: Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@...el.com> > --- > include/linux/kernel.h | 9 +++++++++ > 1 file changed, 9 insertions(+) Since stddef.h ends up needing this macro, and kernel.h includes stddef.h, why not put this macro in stddef.h instead? Then the open-coded version of it in stddef (your last patch) can use sizeof_member()? Otherwise, yes, looks good. (Though I might re-order the patches so the last patch is the tree-wide swap -- then you don't need the exclusions, I think?) -Kees > > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > index 4fa360a13c1e..0b80d8bb3978 100644 > --- a/include/linux/kernel.h > +++ b/include/linux/kernel.h > @@ -79,6 +79,15 @@ > */ > #define round_down(x, y) ((x) & ~__round_mask(x, y)) > > +/** > + * sizeof_member - get the size of a struct's member > + * @T: the target struct > + * @m: the target struct's member > + * Return: the size of @m in the struct definition without having a > + * declared instance of @T. > + */ > +#define sizeof_member(T, m) (sizeof(((T *)0)->m)) > + > /** > * FIELD_SIZEOF - get the size of a struct's field > * @t: the target struct > -- > 2.17.1 > -- Kees Cook
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