Clang supports the 'require_explicit_initialization' attribute on struct fields to indicate that a field must be initialized explicitly by the user when the object is constructed. When an aggregate initializer or uninitialized variable omits an annotated field, Clang emits a -Wuninitialized-explicit-init warning (enabled by default).
Add the __must_init macro to include/linux/compiler_attributes.h (which is included by include/linux/compiler_types.h and include/linux/compiler.h) so kernel structs with error-prone initialization (such as mandatory callbacks or cleanup handlers) can enforce explicit initialization at compile time, as discussed at the Linux Plumbers Conference. The shorter __must_init spelling, rather than the attribute's full name, keeps annotated struct members readable and was suggested by Greg Kroah-Hartman. Note that Clang does not yet diagnose file-scope objects declared without any initializer (initializers at file scope that omit the field are diagnosed), see https://github.com/llvm/llvm-project/issues/232483. Also teach Sphinx (Documentation/conf.py), kernel-doc (tools/lib/python/kdoc/xforms_lists.py), and checkpatch.pl about the new attribute macro. Link: https://lpc.events/event/20/contributions/2392/ Link: https://lore.kernel.org/lkml/2026101532-fantastic-deafness-e04c@gregkh/ Acked-by: Miguel Ojeda <[email protected]> Reviewed-by: Nick Desaulniers <[email protected]> Reviewed-by: Nathan Chancellor <[email protected]> Acked-by: Greg Kroah-Hartman <[email protected]> Signed-off-by: Ian Rogers <[email protected]> --- Documentation/conf.py | 1 + include/linux/compiler_attributes.h | 12 ++++++++++++ scripts/checkpatch.pl | 1 + tools/lib/python/kdoc/xforms_lists.py | 1 + 4 files changed, 15 insertions(+) diff --git a/Documentation/conf.py b/Documentation/conf.py index 5ab26ce89daf..baaa4035258c 100644 --- a/Documentation/conf.py +++ b/Documentation/conf.py @@ -203,6 +203,7 @@ c_id_attributes = [ "__noreturn", "__packed", "__pure", + "__must_init", "__section", "__always_unused", "__maybe_unused", diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h index 476c4c560d17..b9c0b56dd22e 100644 --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -322,6 +322,18 @@ */ #define __pure __attribute__((__pure__)) +/* + * Optional: not supported by gcc + * Optional: only supported since clang >= 20.0 + * + * clang: https://clang.llvm.org/docs/AttributeReference.html#require-explicit-initialization + */ +#if __has_attribute(__require_explicit_initialization__) +# define __must_init __attribute__((__require_explicit_initialization__)) +#else +# define __must_init +#endif + /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-section-function-attribute * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-section-variable-attribute diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index c9840f5219c2..5232f66d2b80 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -6860,6 +6860,7 @@ sub process { "noreturn" => "__noreturn", "packed" => "__packed", "pure" => "__pure", + "require_explicit_initialization" => "__must_init", "section" => "__section", "used" => "__used", "weak" => "__weak" diff --git a/tools/lib/python/kdoc/xforms_lists.py b/tools/lib/python/kdoc/xforms_lists.py index 320f977c5bac..3c744cbd2f34 100644 --- a/tools/lib/python/kdoc/xforms_lists.py +++ b/tools/lib/python/kdoc/xforms_lists.py @@ -36,6 +36,7 @@ class CTransforms: (CMatch("CRYPTO_MINALIGN_ATTR"), ""), (CMatch("__private"), ""), (CMatch("__rcu"), ""), + (CMatch("__must_init"), ""), (CMatch("____cacheline_aligned_in_smp"), ""), (CMatch("____cacheline_aligned"), ""), (CMatch("__cacheline_group_(?:begin|end)"), ""), -- 2.56.0.313.g2479322e68-goog
