| Message ID | 20230817143352.132583-3-lucas.segarra.fernandez@intel.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | Add debugfs pm_status for qat driver | expand |
Hi Lucas, On 2023-08-17 16:33, Lucas Segarra Fernandez wrote: > Introduce ARRAY_SIZE_OF_FIELD() in order to get the number of elements > of an array struct field. > > Signed-off-by: Lucas Segarra Fernandez <lucas.segarra.fernandez@intel.com> > Reviewed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com> > Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> > --- > include/linux/array_size.h | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/include/linux/array_size.h b/include/linux/array_size.h > index 06d7d83196ca..37dac0473b5c 100644 > --- a/include/linux/array_size.h > +++ b/include/linux/array_size.h > @@ -10,4 +10,12 @@ > */ > #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr)) > > +/* > + * ARRAY_SIZE_OF_FIELD - get the number of elements of an array struct field > + * > + * @TYPE: The structure containing the field of interest > + * @MEMBER: The array field to be sized > + */ > +#define ARRAY_SIZE_OF_FIELD(TYPE, MEMBER) ARRAY_SIZE((((TYPE *)0)->MEMBER)) Some comment about the name: ARRAY_SIZE() is rather ambiguous, as there's array_size()[1], which means the number of bytes needed to represent the array. I suggest a name based on - _Lengthof() It has been proposed to ISO C to get the number of elements of an array: <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2529.pdf>. - sizeof_field() The kernel macro for the size of a struct member So, how about lengthof_field()? Cheers, Alex [1]: The definition of array_size() is here: $ grep -rnB10 define.array_size include/linux/overflow.h 238-/** 239- * array_size() - Calculate size of 2-dimensional array. 240- * @a: dimension one 241- * @b: dimension two 242- * 243- * Calculates size of 2-dimensional array: @a * @b. 244- * 245- * Returns: number of bytes needed to represent the array or SIZE_MAX on 246- * overflow. 247- */ 248:#define array_size(a, b) size_mul(a, b) > + > #endif /* _LINUX_ARRAY_SIZE_H */
On Thu, Aug 17, 2023 at 11:34 PM Alejandro Colomar <alx@kernel.org> wrote: > On 2023-08-17 16:33, Lucas Segarra Fernandez wrote: ... > Some comment about the name: > > ARRAY_SIZE() is rather ambiguous, as there's array_size()[1], which means the > number of bytes needed to represent the array. I suggest a name based on > > - _Lengthof() It has been proposed to ISO C to get the number of elements > of an array: > <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2529.pdf>. > > - sizeof_field() The kernel macro for the size of a struct member > > So, how about lengthof_field()? TBH I do not understand the motivation of making this kind of confusion and inconsistency. Are you suggesting renaming ARRAY_SIZE() to begin with? If so, it's definitely out of the scope of this series.
Hello Andy, On 2023-08-17 23:30, Andy Shevchenko wrote: > On Thu, Aug 17, 2023 at 11:34 PM Alejandro Colomar <alx@kernel.org> wrote: >> On 2023-08-17 16:33, Lucas Segarra Fernandez wrote: > > ... > >> Some comment about the name: >> >> ARRAY_SIZE() is rather ambiguous, as there's array_size()[1], which means the >> number of bytes needed to represent the array. I suggest a name based on >> >> - _Lengthof() It has been proposed to ISO C to get the number of elements >> of an array: >> <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2529.pdf>. >> >> - sizeof_field() The kernel macro for the size of a struct member >> >> So, how about lengthof_field()? > > TBH I do not understand the motivation of making this kind of > confusion and inconsistency. > Are you suggesting renaming ARRAY_SIZE() > to begin with? No. ARRAY_SIZE is a very old and known API. It is array_size() that is to be blamed, due to having a confusing name. What I suggest is not reusing the root of the name of ARRAY_SIZE(), which since the addition of array_size() may be less unambiguous (IMHO). So, instead of ARRAY_SIZE_*(), which is derived from ARRAY_SIZE(), maybe it would be more unambiguous to use the _Lengthof() name as a root, since nobody has messed with it so far. My suggestion is to keep ARRAY_SIZE() with its old name, but use lengthof_field() for this struct variant of it. It's also a shorter name, which will make for shorter lines. b19d57d0f3cc ("overflow.h: Add flex_array_size() helper") - (Mon Jun 8 20:22:33 2020 -0500) 610b15c50e86 ("overflow.h: Add allocation size calculation helpers") - (Mon May 7 16:47:02 2018 -0700) Nevertheless, it was just a minor suggestion, and if array_size() was seen as a good enough name, it wouldn't be as confusing as it seems to me. If you find them to be fine, go ahead. Cheers, Alex > If so, it's definitely out of the scope of this series. >
diff --git a/include/linux/array_size.h b/include/linux/array_size.h index 06d7d83196ca..37dac0473b5c 100644 --- a/include/linux/array_size.h +++ b/include/linux/array_size.h @@ -10,4 +10,12 @@ */ #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr)) +/* + * ARRAY_SIZE_OF_FIELD - get the number of elements of an array struct field + * + * @TYPE: The structure containing the field of interest + * @MEMBER: The array field to be sized + */ +#define ARRAY_SIZE_OF_FIELD(TYPE, MEMBER) ARRAY_SIZE((((TYPE *)0)->MEMBER)) + #endif /* _LINUX_ARRAY_SIZE_H */