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pin-init blanket implementation changes for v6.17

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Remove the error from the blanket implementations for `[Pin]Init` and
 add implementations for `Result`.
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Merge tag 'pin-init-v6.17-result-blanket' of https://github.com/Rust-for-Linux/linux.git

pin-init blanket implementation changes for v6.17

Remove the error from the blanket implementations for `[Pin]Init` and
add implementations for `Result`.

(Subsequent Devres improvements depend on those pin-init features.)
This commit is contained in:
Danilo Krummrich 2025-06-28 17:25:23 +02:00
commit 14648fc30e
2 changed files with 39 additions and 13 deletions
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12
rust/kernel/block/mq/tag_set.rs
View File

@ -9,7 +9,7 @@
use crate::{
bindings,
block::mq::{operations::OperationsVTable, request::RequestDataWrapper, Operations},
error,
error::{self, Result},
prelude::try_pin_init,
types::Opaque,
};
@ -41,7 +41,7 @@ pub fn new(
// SAFETY: `blk_mq_tag_set` only contains integers and pointers, which
// all are allowed to be 0.
let tag_set: bindings::blk_mq_tag_set = unsafe { core::mem::zeroed() };
let tag_set = core::mem::size_of::<RequestDataWrapper>()
let tag_set: Result<_> = core::mem::size_of::<RequestDataWrapper>()
.try_into()
.map(|cmd_size| {
bindings::blk_mq_tag_set {
@ -56,12 +56,14 @@ pub fn new(
nr_maps: num_maps,
..tag_set
}
});
})
.map(Opaque::new)
.map_err(|e| e.into());
try_pin_init!(TagSet {
inner <- PinInit::<_, error::Error>::pin_chain(Opaque::new(tag_set?), |tag_set| {
inner <- tag_set.pin_chain(|tag_set| {
// SAFETY: we do not move out of `tag_set`.
let tag_set = unsafe { Pin::get_unchecked_mut(tag_set) };
let tag_set: &mut Opaque<_> = unsafe { Pin::get_unchecked_mut(tag_set) };
// SAFETY: `tag_set` is a reference to an initialized `blk_mq_tag_set`.
error::to_result( unsafe { bindings::blk_mq_alloc_tag_set(tag_set.get())})
}),

40
rust/pin-init/src/lib.rs
View File

@ -1390,20 +1390,44 @@ pub fn pin_init_array_from_fn<I, const N: usize, T, E>(
unsafe { pin_init_from_closure(init) }
}
// SAFETY: Every type can be initialized by-value.
unsafe impl<T, E> Init<T, E> for T {
unsafe fn __init(self, slot: *mut T) -> Result<(), E> {
// SAFETY: TODO.
// SAFETY: the `__init` function always returns `Ok(())` and initializes every field of `slot`.
unsafe impl<T> Init<T> for T {
unsafe fn __init(self, slot: *mut T) -> Result<(), Infallible> {
// SAFETY: `slot` is valid for writes by the safety requirements of this function.
unsafe { slot.write(self) };
Ok(())
}
}
// SAFETY: Every type can be initialized by-value. `__pinned_init` calls `__init`.
unsafe impl<T, E> PinInit<T, E> for T {
// SAFETY: the `__pinned_init` function always returns `Ok(())` and initializes every field of
// `slot`. Additionally, all pinning invariants of `T` are upheld.
unsafe impl<T> PinInit<T> for T {
unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), Infallible> {
// SAFETY: `slot` is valid for writes by the safety requirements of this function.
unsafe { slot.write(self) };
Ok(())
}
}
// SAFETY: when the `__init` function returns with
// - `Ok(())`, `slot` was initialized and all pinned invariants of `T` are upheld.
// - `Err(err)`, slot was not written to.
unsafe impl<T, E> Init<T, E> for Result<T, E> {
unsafe fn __init(self, slot: *mut T) -> Result<(), E> {
// SAFETY: `slot` is valid for writes by the safety requirements of this function.
unsafe { slot.write(self?) };
Ok(())
}
}
// SAFETY: when the `__pinned_init` function returns with
// - `Ok(())`, `slot` was initialized and all pinned invariants of `T` are upheld.
// - `Err(err)`, slot was not written to.
unsafe impl<T, E> PinInit<T, E> for Result<T, E> {
unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> {
// SAFETY: TODO.
unsafe { self.__init(slot) }
// SAFETY: `slot` is valid for writes by the safety requirements of this function.
unsafe { slot.write(self?) };
Ok(())
}
}