impl_list_item_mod.rs calls container_of! without unsafe blocks at a
couple of places. Since container_of! is unsafe, the blocks are strictly
necessary.
The problem was so far not visible because the "unsafe-op-in-unsafe-fn"
check is a lint rather than a hard compiler error, and Rust suppresses
lints triggered inside of a macro from another crate.
Thus, the error becomes only visible once someone from within the kernel
crate tries to use linked lists:
error[E0133]: call to unsafe function `core::ptr::mut_ptr::<impl *mut T>::byte_sub`
is unsafe and requires unsafe block
--> rust/kernel/lib.rs:252:29
|
252 | let container_ptr = field_ptr.byte_sub(offset).cast::<$Container>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ call to unsafe function
|
::: rust/kernel/drm/jq.rs:98:1
|
98 | / impl_list_item! {
99 | | impl ListItem<0> for BasicItem { using ListLinks { self.links }; }
100 | | }
| |_- in this macro invocation
|
note: an unsafe function restricts its caller, but its body is safe by default
--> rust/kernel/list/impl_list_item_mod.rs:216:13
|
216 | unsafe fn view_value(me: *mut $crate::list::ListLinks<$num>) -> *const Self {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
::: rust/kernel/drm/jq.rs:98:1
|
98 | / impl_list_item! {
99 | | impl ListItem<0> for BasicItem { using ListLinks { self.links }; }
100 | | }
| |_- in this macro invocation
= note: requested on the command line with `-D unsafe-op-in-unsafe-fn`
= note: this error originates in the macro `$crate::container_of` which comes
from the expansion of the macro `impl_list_item`
Therefore, add unsafe blocks to container_of! calls to fix the issue.
[ As discussed, let's fix the build for those that want to use the
macro within the `kernel` crate now and we can discuss the proper
safety comments afterwards. Thus I removed the ones from the patch.
However, we cannot just avoid the comments with `CLIPPY=1`, so I
provided placeholders for now, like we did in the past. They were
also needed for an `unsafe impl`.
While I am not happy about it, it isn't worse than the current
status (the comments were meant to be there), and at least this
shows what is missing -- our pre-existing "good first issue" [1]
may motivate new contributors to complete them properly.
Finally, I moved one of the existing safety comments one line down
so that Clippy could locate it.
Link: https://github.com/Rust-for-Linux/linux/issues/351 [1]
- Miguel ]
Cc: stable@vger.kernel.org
Fixes: c77f85b347 ("rust: list: remove OFFSET constants")
Suggested-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Philipp Stanner <phasta@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://patch.msgid.link/20260216131613.45344-3-phasta@kernel.org
[ Fixed formatting. Reworded to fix the lint suppression
explanation. Indent build error. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Replace `ListLinksSelfPtr::LIST_LINKS_SELF_PTR_OFFSET` with `unsafe fn
raw_get_self_ptr` which returns a pointer to the field rather than
requiring the caller to do pointer arithmetic.
Implement `HasListLinks::raw_get_list_links` in `impl_has_list_links!`,
narrowing the interface of `HasListLinks` and replacing pointer
arithmetic with `container_of!`.
Modify `impl_list_item` to also invoke `impl_has_list_links!` or
`impl_has_list_links_self_ptr!`. This is necessary to allow
`impl_list_item` to see more of the tokens used by
`impl_has_list_links{,_self_ptr}!`.
A similar API change was discussed on the hrtimer series[1].
Link: https://lore.kernel.org/all/20250224-hrtimer-v3-v6-12-rc2-v9-1-5bd3bf0ce6cc@kernel.org/ [1]
Tested-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Link: https://lore.kernel.org/r/20250709-list-no-offset-v4-6-a429e75840a9@gmail.com
[ Fixed broken intra-doc links. Used the renamed
`Opaque::cast_into`. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
There's a comprehensive example in `rust/kernel/list.rs` but it doesn't
exercise the `using ListLinksSelfPtr` variant nor the generic cases. Add
that here. Generalize `impl_has_list_links_self_ptr` to handle nested
fields in the same manner as `impl_has_list_links`.
Tested-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Link: https://lore.kernel.org/r/20250709-list-no-offset-v4-5-a429e75840a9@gmail.com
[ Fixed Rust < 1.82 build by enabling the `offset_of_nested`
feature. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
When we renamed `Opaque::raw_get` to `cast_into`, there was one
replacement that was not supposed to be there.
It does not cause an issue so far because it is inside a macro rule (the
`ListLinksSelfPtr` one) that is unused so far. However, it will start
to be used soon.
Thus fix it now.
Fixes: 64fb810bce ("rust: types: rename Opaque::raw_get to cast_into")
Reviewed-by: Tamir Duberstein <tamird@gmail.com>
Link: https://lore.kernel.org/r/20250719183649.596051-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
In the previous patch we added Opaque::cast_from() that performs the
opposite operation to Opaque::raw_get(). For consistency with this
naming, rename raw_get() to cast_from().
There are a few other options such as calling cast_from() something
closer to raw_get() rather than renaming this method. However, I could
not find a great naming scheme that works with raw_get(). The previous
version of this patch used from_raw(), but functions of that name
typically have a different signature, so that's not a great option.
Suggested-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Benno Lossin <lossin@kernel.org>
Acked-by: Andreas Hindborg <a.hindborg@kernel.org>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250624-opaque-from-raw-v2-2-e4da40bdc59c@google.com
[ Removed `HrTimer::raw_get` change. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
In Rust 1.51.0, Clippy introduced the `ptr_as_ptr` lint [1]:
> Though `as` casts between raw pointers are not terrible,
> `pointer::cast` is safer because it cannot accidentally change the
> pointer's mutability, nor cast the pointer to other types like `usize`.
There are a few classes of changes required:
- Modules generated by bindgen are marked
`#[allow(clippy::ptr_as_ptr)]`.
- Inferred casts (` as _`) are replaced with `.cast()`.
- Ascribed casts (` as *... T`) are replaced with `.cast::<T>()`.
- Multistep casts from references (` as *const _ as *const T`) are
replaced with `core::ptr::from_ref(&x).cast()` with or without `::<T>`
according to the previous rules. The `core::ptr::from_ref` call is
required because `(x as *const _).cast::<T>()` results in inference
failure.
- Native literal C strings are replaced with `c_str!().as_char_ptr()`.
- `*mut *mut T as _` is replaced with `let *mut *const T = (*mut *mut
T)`.cast();` since pointer to pointer can be confusing.
Apply these changes and enable the lint -- no functional change
intended.
Link: https://rust-lang.github.io/rust-clippy/master/index.html#ptr_as_ptr [1]
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250615-ptr-as-ptr-v12-1-f43b024581e8@gmail.com
[ Added `.cast()` for `opp`. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Support linked lists that can hold many different structs at once. This
is generally done using trait objects. The main challenge is figuring
what the struct is given only a pointer to the ListLinks.
We do this by storing a pointer to the struct next to the ListLinks
field. The container_of operation will then just read that pointer. When
the type is a trait object, that pointer will be a fat pointer whose
metadata is a vtable that tells you what kind of struct it is.
Heterogeneous lists are heavily used by Rust Binder. There are a lot of
so-called todo lists containing various events that need to be delivered
to userspace next time userspace calls into the driver. And there are
quite a few different todo item types: incoming transaction, changes to
refcounts, death notifications, and more.
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240814-linked-list-v5-9-f5f5e8075da0@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
