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bitfield: Ensure the return values of helper functions are checked 

As type##_replace_bits() has no side effects it is only useful if its
return value is checked. Add __must_check to enforce this usage. To have
the bits replaced in-place typep##_replace_bits() can be used instead.

Although, type_##_get_bits() and type_##_encode_bits() are harder to misuse
they are still only useful if the return value is checked. For
consistency, also add __must_check to these.

Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>
pull/1311/head
Ben Horgan 2025-07-09 10:38:08 +01:00 committed by Yury Norov
parent dcb23e1878
commit e2b02d382a
1 changed files with 4 additions and 4 deletions
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8
include/linux/bitfield.h
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@ -189,14 +189,14 @@ static __always_inline u64 field_mask(u64 field)
} }
#define field_max(field) ((typeof(field))field_mask(field)) #define field_max(field) ((typeof(field))field_mask(field))
#define ____MAKE_OP(type,base,to,from) \ #define ____MAKE_OP(type,base,to,from) \
static __always_inline __##type type##_encode_bits(base v, base field) \ static __always_inline __##type __must_check type##_encode_bits(base v, base field) \
{ \ { \
if (__builtin_constant_p(v) && (v & ~field_mask(field))) \ if (__builtin_constant_p(v) && (v & ~field_mask(field))) \
__field_overflow(); \ __field_overflow(); \
return to((v & field_mask(field)) * field_multiplier(field)); \ return to((v & field_mask(field)) * field_multiplier(field)); \
} \ } \
static __always_inline __##type type##_replace_bits(__##type old, \ static __always_inline __##type __must_check type##_replace_bits(__##type old, \
base val, base field) \ base val, base field) \
{ \ { \
return (old & ~to(field)) | type##_encode_bits(val, field); \ return (old & ~to(field)) | type##_encode_bits(val, field); \
} \ } \
@ -205,7 +205,7 @@ static __always_inline void type##p_replace_bits(__##type *p, \
{ \ { \
*p = (*p & ~to(field)) | type##_encode_bits(val, field); \ *p = (*p & ~to(field)) | type##_encode_bits(val, field); \
} \ } \
static __always_inline base type##_get_bits(__##type v, base field) \ static __always_inline base __must_check type##_get_bits(__##type v, base field) \
{ \ { \
return (from(v) & field)/field_multiplier(field); \ return (from(v) & field)/field_multiplier(field); \
} }