| Message ID | 20240210011643.1706285-1-keescook@chromium.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | stddef: Allow attributes to be used when creating flex arrays | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On 2/9/24 19:16, Kees Cook wrote: > With the coming support for the __counted_by struct member attribute, we > will need a way to add such annotations to the places where > DECLARE_FLEX_ARRAY() is used. Introduce DECLARE_FLEX_ARRAY_ATTR() which > takes a third argument: the attributes to apply to the flexible array. > > Cc: Gustavo A. R. Silva <gustavoars@kernel.org> > Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> > Cc: Dan Williams <dan.j.williams@intel.com> > Cc: Keith Packard <keithp@keithp.com> > Cc: Miguel Ojeda <ojeda@kernel.org> > Cc: Alexey Dobriyan <adobriyan@gmail.com> > Cc: Dmitry Antipov <dmantipov@yandex.ru> > Signed-off-by: Kees Cook <keescook@chromium.org> Nice! Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> Thanks
On 10/02/2024 02.16, Kees Cook wrote: > With the coming support for the __counted_by struct member attribute, we > will need a way to add such annotations to the places where > DECLARE_FLEX_ARRAY() is used. Introduce DECLARE_FLEX_ARRAY_ATTR() which > takes a third argument: the attributes to apply to the flexible array. > > - * __DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union > - * > + * __DECLARE_FLEX_ARRAY_ATTR() - Declare a flexible array usable in a union > * @TYPE: The type of each flexible array element > * @NAME: The name of the flexible array member > + * @ATTRS: The list of member attributes to apply > * > * In order to have a flexible array member in a union or alone in a > * struct, it needs to be wrapped in an anonymous struct with at least 1 > * named member, but that member can be empty. > */ > -#define __DECLARE_FLEX_ARRAY(TYPE, NAME) \ > +#define __DECLARE_FLEX_ARRAY_ATTR(TYPE, NAME, ATTRS) \ > struct { \ > struct { } __empty_ ## NAME; \ > - TYPE NAME[]; \ > + TYPE NAME[] ATTRS; \ > } Is it too ugly to not introduce a separate _ATTR macro but instead just do #define __DECLARE_FLEX_ARRAY(TYPE, NAME, ...) \ ... TYPE NAME[] __VA_ARGS__; ? Rasmus
On Tue, Feb 13, 2024 at 08:22:00AM +0100, Rasmus Villemoes wrote: > On 10/02/2024 02.16, Kees Cook wrote: > > With the coming support for the __counted_by struct member attribute, we > > will need a way to add such annotations to the places where > > DECLARE_FLEX_ARRAY() is used. Introduce DECLARE_FLEX_ARRAY_ATTR() which > > takes a third argument: the attributes to apply to the flexible array. > > > > > - * __DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union > > - * > > + * __DECLARE_FLEX_ARRAY_ATTR() - Declare a flexible array usable in a union > > * @TYPE: The type of each flexible array element > > * @NAME: The name of the flexible array member > > + * @ATTRS: The list of member attributes to apply > > * > > * In order to have a flexible array member in a union or alone in a > > * struct, it needs to be wrapped in an anonymous struct with at least 1 > > * named member, but that member can be empty. > > */ > > -#define __DECLARE_FLEX_ARRAY(TYPE, NAME) \ > > +#define __DECLARE_FLEX_ARRAY_ATTR(TYPE, NAME, ATTRS) \ > > struct { \ > > struct { } __empty_ ## NAME; \ > > - TYPE NAME[]; \ > > + TYPE NAME[] ATTRS; \ > > } > > Is it too ugly to not introduce a separate _ATTR macro but instead just do > > #define __DECLARE_FLEX_ARRAY(TYPE, NAME, ...) \ > ... > TYPE NAME[] __VA_ARGS__; > > ? Oh, yes. That will be much nicer, I think! I will send a v2...
diff --git a/include/linux/stddef.h b/include/linux/stddef.h index 929d67710cc5..eb51f6727ecf 100644 --- a/include/linux/stddef.h +++ b/include/linux/stddef.h @@ -81,8 +81,20 @@ enum { __struct_group(TAG, NAME, /* no attrs */, MEMBERS) /** - * DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union + * DECLARE_FLEX_ARRAY_ATTR() - Declare a flexible array usable in a union + * @TYPE: The type of each flexible array element + * @NAME: The name of the flexible array member + * @ATTRS: The list of member attributes to apply * + * In order to have a flexible array member in a union or alone in a + * struct, it needs to be wrapped in an anonymous struct with at least 1 + * named member, but that member can be empty. + */ +#define DECLARE_FLEX_ARRAY_ATTR(TYPE, NAME, ATTRS) \ + __DECLARE_FLEX_ARRAY_ATTR(TYPE, NAME, ATTRS) + +/** + * DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union * @TYPE: The type of each flexible array element * @NAME: The name of the flexible array member * @@ -91,6 +103,6 @@ enum { * named member, but that member can be empty. */ #define DECLARE_FLEX_ARRAY(TYPE, NAME) \ - __DECLARE_FLEX_ARRAY(TYPE, NAME) + DECLARE_FLEX_ARRAY_ATTR(TYPE, NAME, /* no attributes */) #endif diff --git a/include/uapi/linux/stddef.h b/include/uapi/linux/stddef.h index 2ec6f35cda32..5499c08ad011 100644 --- a/include/uapi/linux/stddef.h +++ b/include/uapi/linux/stddef.h @@ -31,24 +31,37 @@ #ifdef __cplusplus /* sizeof(struct{}) is 1 in C++, not 0, can't use C version of the macro. */ -#define __DECLARE_FLEX_ARRAY(T, member) \ - T member[0] +#define __DECLARE_FLEX_ARRAY_ATTR(TYPE, NAME, ATTRS) \ + TYPE NAME[0] ATTRS +#define __DECLARE_FLEX_ARRAY(TYPE, NAME) \ + __DECLARE_FLEX_ARRAY_ATTR(TYPE, NAME, /* no attributes */) #else /** - * __DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union - * + * __DECLARE_FLEX_ARRAY_ATTR() - Declare a flexible array usable in a union * @TYPE: The type of each flexible array element * @NAME: The name of the flexible array member + * @ATTRS: The list of member attributes to apply * * In order to have a flexible array member in a union or alone in a * struct, it needs to be wrapped in an anonymous struct with at least 1 * named member, but that member can be empty. */ -#define __DECLARE_FLEX_ARRAY(TYPE, NAME) \ +#define __DECLARE_FLEX_ARRAY_ATTR(TYPE, NAME, ATTRS) \ struct { \ struct { } __empty_ ## NAME; \ - TYPE NAME[]; \ + TYPE NAME[] ATTRS; \ } +/** + * __DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union + * @TYPE: The type of each flexible array element + * @NAME: The name of the flexible array member + * + * In order to have a flexible array member in a union or alone in a + * struct, it needs to be wrapped in an anonymous struct with at least 1 + * named member, but that member can be empty. + */ +#define __DECLARE_FLEX_ARRAY(TYPE, NAME) \ + __DECLARE_FLEX_ARRAY_ATTR(TYPE, NAME, /* no attributes */) #endif #ifndef __counted_by
With the coming support for the __counted_by struct member attribute, we will need a way to add such annotations to the places where DECLARE_FLEX_ARRAY() is used. Introduce DECLARE_FLEX_ARRAY_ATTR() which takes a third argument: the attributes to apply to the flexible array. Cc: Gustavo A. R. Silva <gustavoars@kernel.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Keith Packard <keithp@keithp.com> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Dmitry Antipov <dmantipov@yandex.ru> Signed-off-by: Kees Cook <keescook@chromium.org> --- include/linux/stddef.h | 16 ++++++++++++++-- include/uapi/linux/stddef.h | 25 +++++++++++++++++++------ 2 files changed, 33 insertions(+), 8 deletions(-)