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b20fbbc08a
Add a compile-time check that `*$ptr` is of the type of `$type->$($f)*`.
Rename those placeholders for clarity.
Given the incorrect usage:
> diff --git a/rust/kernel/rbtree.rs b/rust/kernel/rbtree.rs
> index 8d978c896747..6a7089149878 100644
> --- a/rust/kernel/rbtree.rs
> +++ b/rust/kernel/rbtree.rs
> @@ -329,7 +329,7 @@ fn raw_entry(&mut self, key: &K) -> RawEntry<'_, K, V> {
> while !(*child_field_of_parent).is_null() {
> let curr = *child_field_of_parent;
> // SAFETY: All links fields we create are in a `Node<K, V>`.
> - let node = unsafe { container_of!(curr, Node<K, V>, links) };
> + let node = unsafe { container_of!(curr, Node<K, V>, key) };
>
> // SAFETY: `node` is a non-null node so it is valid by the type invariants.
> match key.cmp(unsafe { &(*node).key }) {
this patch produces the compilation error:
> error[E0308]: mismatched types
> --> rust/kernel/lib.rs:220:45
> |
> 220 | $crate::assert_same_type(field_ptr, (&raw const (*container_ptr).$($fields)*).cast_mut());
> | ------------------------ --------- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `*mut rb_node`, found `*mut K`
> | | |
> | | expected all arguments to be this `*mut bindings::rb_node` type because they need to match the type of this parameter
> | arguments to this function are incorrect
> |
> ::: rust/kernel/rbtree.rs:270:6
> |
> 270 | impl<K, V> RBTree<K, V>
> | - found this type parameter
> ...
> 332 | let node = unsafe { container_of!(curr, Node<K, V>, key) };
> | ------------------------------------ in this macro invocation
> |
> = note: expected raw pointer `*mut bindings::rb_node`
> found raw pointer `*mut K`
> note: function defined here
> --> rust/kernel/lib.rs:227:8
> |
> 227 | pub fn assert_same_type<T>(_: T, _: T) {}
> | ^^^^^^^^^^^^^^^^ - ---- ---- this parameter needs to match the `*mut bindings::rb_node` type of parameter #1
> | | |
> | | parameter #2 needs to match the `*mut bindings::rb_node` type of this parameter
> | parameter #1 and parameter #2 both reference this parameter `T`
> = note: this error originates in the macro `container_of` (in Nightly builds, run with -Z macro-backtrace for more info)
[ We decided to go with a variation of v1 [1] that became v4, since it
seems like the obvious approach, the error messages seem good enough
and the debug performance should be fine, given the kernel is always
built with -O2.
In the future, we may want to make the helper non-hidden, with
proper documentation, for others to use.
[1] https://lore.kernel.org/rust-for-linux/CANiq72kQWNfSV0KK6qs6oJt+aGdgY=hXg=wJcmK3zYcokY1LNw@mail.gmail.com/
- Miguel ]
Suggested-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/all/CAH5fLgh6gmqGBhPMi2SKn7mCmMWfOSiS0WP5wBuGPYh9ZTAiww@mail.gmail.com/
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Link: https://lore.kernel.org/r/20250529-b4-container-of-type-check-v4-1-bf3a7ad73cec@gmail.com
[ Added intra-doc link. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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| alloc | ||
| block | ||
| fs | ||
| list | ||
| net | ||
| sync | ||
| time | ||
| .gitignore | ||
| alloc.rs | ||
| block.rs | ||
| build_assert.rs | ||
| cred.rs | ||
| device_id.rs | ||
| device.rs | ||
| devres.rs | ||
| dma.rs | ||
| driver.rs | ||
| error.rs | ||
| faux.rs | ||
| firmware.rs | ||
| fs.rs | ||
| generated_arch_static_branch_asm.rs.S | ||
| init.rs | ||
| io.rs | ||
| ioctl.rs | ||
| jump_label.rs | ||
| kunit.rs | ||
| lib.rs | ||
| list.rs | ||
| miscdevice.rs | ||
| net.rs | ||
| of.rs | ||
| page.rs | ||
| pci.rs | ||
| pid_namespace.rs | ||
| platform.rs | ||
| prelude.rs | ||
| print.rs | ||
| rbtree.rs | ||
| revocable.rs | ||
| security.rs | ||
| seq_file.rs | ||
| sizes.rs | ||
| static_assert.rs | ||
| std_vendor.rs | ||
| str.rs | ||
| sync.rs | ||
| task.rs | ||
| time.rs | ||
| tracepoint.rs | ||
| transmute.rs | ||
| types.rs | ||
| uaccess.rs | ||
| workqueue.rs | ||
| xarray.rs | ||