diff options
Diffstat (limited to 'rust/kernel/init/macros.rs')
| -rw-r--r-- | rust/kernel/init/macros.rs | 116 |
1 files changed, 52 insertions, 64 deletions
diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs index 0b0ffbc901a7..5063b45970f3 100644 --- a/rust/kernel/init/macros.rs +++ b/rust/kernel/init/macros.rs @@ -994,7 +994,6 @@ macro_rules! __pin_data { /// - `init_slot`: recursively creates the code that initializes all fields in `slot`. /// - `make_initializer`: recursively create the struct initializer that guarantees that every /// field has been initialized exactly once. -/// - `forget_guards`: recursively forget the drop guards for every field. #[doc(hidden)] #[macro_export] macro_rules! __init_internal { @@ -1034,6 +1033,7 @@ macro_rules! __init_internal { $crate::__init_internal!(init_slot($($use_data)?): @data(data), @slot(slot), + @guards(), @munch_fields($($fields)*,), ); // We use unreachable code to ensure that all fields have been mentioned exactly @@ -1048,10 +1048,6 @@ macro_rules! __init_internal { @acc(), ); } - // Forget all guards, since initialization was a success. - $crate::__init_internal!(forget_guards: - @munch_fields($($fields)*,), - ); } Ok(__InitOk) } @@ -1065,13 +1061,17 @@ macro_rules! __init_internal { (init_slot($($use_data:ident)?): @data($data:ident), @slot($slot:ident), + @guards($($guards:ident,)*), @munch_fields($(,)?), ) => { - // Endpoint of munching, no fields are left. + // Endpoint of munching, no fields are left. If execution reaches this point, all fields + // have been initialized. Therefore we can now dismiss the guards by forgetting them. + $(::core::mem::forget($guards);)* }; (init_slot($use_data:ident): // `use_data` is present, so we use the `data` to init fields. @data($data:ident), @slot($slot:ident), + @guards($($guards:ident,)*), // In-place initialization syntax. @munch_fields($field:ident <- $val:expr, $($rest:tt)*), ) => { @@ -1082,24 +1082,28 @@ macro_rules! __init_internal { // return when an error/panic occurs. // We also use the `data` to require the correct trait (`Init` or `PinInit`) for `$field`. unsafe { $data.$field(::core::ptr::addr_of_mut!((*$slot).$field), $field)? }; - // Create the drop guard. - // - // We only give access to `&DropGuard`, so it cannot be forgotten via safe code. + // Create the drop guard: // - // SAFETY: We forget the guard later when initialization has succeeded. - let $field = &unsafe { - $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) - }; + // We rely on macro hygiene to make it impossible for users to access this local variable. + // We use `paste!` to create new hygiene for `$field`. + ::kernel::macros::paste! { + // SAFETY: We forget the guard later when initialization has succeeded. + let [<$field>] = unsafe { + $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) + }; - $crate::__init_internal!(init_slot($use_data): - @data($data), - @slot($slot), - @munch_fields($($rest)*), - ); + $crate::__init_internal!(init_slot($use_data): + @data($data), + @slot($slot), + @guards([<$field>], $($guards,)*), + @munch_fields($($rest)*), + ); + } }; (init_slot(): // No `use_data`, so we use `Init::__init` directly. @data($data:ident), @slot($slot:ident), + @guards($($guards:ident,)*), // In-place initialization syntax. @munch_fields($field:ident <- $val:expr, $($rest:tt)*), ) => { @@ -1109,24 +1113,28 @@ macro_rules! __init_internal { // SAFETY: `slot` is valid, because we are inside of an initializer closure, we // return when an error/panic occurs. unsafe { $crate::init::Init::__init($field, ::core::ptr::addr_of_mut!((*$slot).$field))? }; - // Create the drop guard. - // - // We only give access to `&DropGuard`, so it cannot be forgotten via safe code. + // Create the drop guard: // - // SAFETY: We forget the guard later when initialization has succeeded. - let $field = &unsafe { - $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) - }; + // We rely on macro hygiene to make it impossible for users to access this local variable. + // We use `paste!` to create new hygiene for `$field`. + ::kernel::macros::paste! { + // SAFETY: We forget the guard later when initialization has succeeded. + let [<$field>] = unsafe { + $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) + }; - $crate::__init_internal!(init_slot(): - @data($data), - @slot($slot), - @munch_fields($($rest)*), - ); + $crate::__init_internal!(init_slot(): + @data($data), + @slot($slot), + @guards([<$field>], $($guards,)*), + @munch_fields($($rest)*), + ); + } }; (init_slot($($use_data:ident)?): @data($data:ident), @slot($slot:ident), + @guards($($guards:ident,)*), // Init by-value. @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), ) => { @@ -1137,18 +1145,21 @@ macro_rules! __init_internal { unsafe { ::core::ptr::write(::core::ptr::addr_of_mut!((*$slot).$field), $field) }; // Create the drop guard: // - // We only give access to `&DropGuard`, so it cannot be accidentally forgotten. - // - // SAFETY: We forget the guard later when initialization has succeeded. - let $field = &unsafe { - $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) - }; + // We rely on macro hygiene to make it impossible for users to access this local variable. + // We use `paste!` to create new hygiene for `$field`. + ::kernel::macros::paste! { + // SAFETY: We forget the guard later when initialization has succeeded. + let [<$field>] = unsafe { + $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) + }; - $crate::__init_internal!(init_slot($($use_data)?): - @data($data), - @slot($slot), - @munch_fields($($rest)*), - ); + $crate::__init_internal!(init_slot($($use_data)?): + @data($data), + @slot($slot), + @guards([<$field>], $($guards,)*), + @munch_fields($($rest)*), + ); + } }; (make_initializer: @slot($slot:ident), @@ -1191,29 +1202,6 @@ macro_rules! __init_internal { @acc($($acc)* $field: ::core::panic!(),), ); }; - (forget_guards: - @munch_fields($(,)?), - ) => { - // Munching finished. - }; - (forget_guards: - @munch_fields($field:ident <- $val:expr, $($rest:tt)*), - ) => { - unsafe { $crate::init::__internal::DropGuard::forget($field) }; - - $crate::__init_internal!(forget_guards: - @munch_fields($($rest)*), - ); - }; - (forget_guards: - @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), - ) => { - unsafe { $crate::init::__internal::DropGuard::forget($field) }; - - $crate::__init_internal!(forget_guards: - @munch_fields($($rest)*), - ); - }; } #[doc(hidden)] |