diff options
| author | Benno Lossin <lossin@kernel.org> | 2026-03-02 15:04:15 +0100 |
|---|---|---|
| committer | Miguel Ojeda <ojeda@kernel.org> | 2026-03-06 02:05:46 +0100 |
| commit | 580cc37b1de4fcd9997c48d7080e744533f09f36 (patch) | |
| tree | 46c823e96e09be730789cdf918e46edd1cff9d53 /rust | |
| parent | a075082a15e7f5c4889d0cbb51a4041c332cb00c (diff) | |
rust: pin-init: internal: init: document load-bearing fact of field accessors
The functions `[Pin]Init::__[pinned_]init` and `ptr::write` called from
the `init!` macro require the passed pointer to be aligned. This fact is
ensured by the creation of field accessors to previously initialized
fields.
Since we missed this very important fact from the beginning [1],
document it in the code.
Link: https://rust-for-linux.zulipchat.com/#narrow/channel/561532-pin-init/topic/initialized.20field.20accessor.20detection/with/576210658 [1]
Fixes: 90e53c5e70a6 ("rust: add pin-init API core")
Cc: <stable@vger.kernel.org> # 6.6.y, 6.12.y: 42415d163e5d: rust: pin-init: add references to previously initialized fields
Cc: <stable@vger.kernel.org> # 6.6.y, 6.12.y, 6.18.y, 6.19.y
Signed-off-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260302140424.4097655-2-lossin@kernel.org
[ Updated Cc: stable@ tags as discussed. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'rust')
| -rw-r--r-- | rust/pin-init/internal/src/init.rs | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/rust/pin-init/internal/src/init.rs b/rust/pin-init/internal/src/init.rs index da53adc44ecf..738f62c8105c 100644 --- a/rust/pin-init/internal/src/init.rs +++ b/rust/pin-init/internal/src/init.rs @@ -251,6 +251,10 @@ fn init_fields( }); // Again span for better diagnostics let write = quote_spanned!(ident.span()=> ::core::ptr::write); + // NOTE: the field accessor ensures that the initialized field is properly aligned. + // Unaligned fields will cause the compiler to emit E0793. We do not support + // unaligned fields since `Init::__init` requires an aligned pointer; the call to + // `ptr::write` below has the same requirement. let accessor = if pinned { let project_ident = format_ident!("__project_{ident}"); quote! { @@ -278,6 +282,10 @@ fn init_fields( InitializerKind::Init { ident, value, .. } => { // Again span for better diagnostics let init = format_ident!("init", span = value.span()); + // NOTE: the field accessor ensures that the initialized field is properly aligned. + // Unaligned fields will cause the compiler to emit E0793. We do not support + // unaligned fields since `Init::__init` requires an aligned pointer; the call to + // `ptr::write` below has the same requirement. let (value_init, accessor) = if pinned { let project_ident = format_ident!("__project_{ident}"); ( |