linux-toradex.git/rust/kernel/rbtree.rs, branch v7.0-rc6

Merge tag 'rust-6.20-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

2026-02-10T19:53:01+00:00

Pull rust updates from Miguel Ojeda:
 "Toolchain and infrastructure:

   - Add '__rust_helper' annotation to the C helpers

     This is needed to inline these helpers into Rust code

   - Remove imports available via the prelude, treewide

     This was possible thanks to a new lint in Klint that Gary has
     implemented -- more Klint-related changes, including initial
     upstream support, are coming

   - Deduplicate pin-init flags

  'kernel' crate:

   - Add support for calling a function exactly once with the new
     'do_once_lite!' macro (and 'OnceLite' type)

     Based on this, add 'pr_*_once!' macros to print only once

   - Add 'impl_flags!' macro for defining common bitflags operations:

         impl_flags!(
             /// Represents multiple permissions.
             #[derive(Debug, Clone, Default, Copy, PartialEq, Eq)]
             pub struct Permissions(u32);

             /// Represents a single permission.
             #[derive(Debug, Clone, Copy, PartialEq, Eq)]
             pub enum Permission {
                 /// Read permission.
                 Read = 1 << 0,

                 /// Write permission.
                 Write = 1 << 1,

                 /// Execute permission.
                 Execute = 1 << 2,
             }
         );

         let mut f: Permissions = Permission::Read | Permission::Write;
         assert!(f.contains(Permission::Read));
         assert!(!f.contains(Permission::Execute));

         f |= Permission::Execute;
         assert!(f.contains(Permission::Execute));

         let f2: Permissions = Permission::Write | Permission::Execute;
         assert!((f ^ f2).contains(Permission::Read));
         assert!(!(f ^ f2).contains(Permission::Write));

   - 'bug' module: support 'CONFIG_DEBUG_BUGVERBOSE_DETAILED' in the
     'warn_on!' macro in order to show the evaluated condition alongside
     the file path:

          ------------[ cut here ]------------
          WARNING: [val == 1] linux/samples/rust/rust_minimal.rs:27 at ...
          Modules linked in: rust_minimal(+)

   - Add safety module with 'unsafe_precondition_assert!' macro,
     currently a wrapper for 'debug_assert!', intended to mark the
     validation of safety preconditions where possible:

         /// # Safety
         ///
         /// The caller must ensure that `index` is less than `N`.
         unsafe fn set_unchecked(&mut self, index: usize, value: T) {
             unsafe_precondition_assert!(
                 index < N,
                 "set_unchecked() requires index ({index}) < N ({N})"
             );

             ...
         }

   - Add instructions to 'build_assert!' documentation requesting to
     always inline functions when used with function arguments

   - 'ptr' module: replace 'build_assert!' with a 'const' one

   - 'rbtree' module: reduce unsafe blocks on pointer derefs

   - 'transmute' module: implement 'FromBytes' and 'AsBytes' for
     inhabited ZSTs, and use it in Nova

   - More treewide replacements of 'c_str!' with C string literals

  'macros' crate:

   - Rewrite most procedural macros ('module!', 'concat_idents!',
     '#[export]', '#[vtable]', '#[kunit_tests]') to use the 'syn'
     parsing library which we introduced last cycle, with better
     diagnostics

     This also allows to support '#[cfg]' properly in the '#[vtable]'
     macro, to support arbitrary types in 'module!' macro (not just an
     identifier) and to remove several custom parsing helpers we had

   - Use 'quote!' from the recently vendored 'quote' library and remove
     our custom one

     The vendored one also allows us to avoid quoting '"' and '{}'
     inside the template anymore and editors can now highlight it. In
     addition, it improves robustness as it eliminates the need for
     string quoting and escaping

   - Use 'pin_init::zeroed()' to simplify KUnit code

  'pin-init' crate:

   - Rewrite all procedural macros ('[pin_]init!', '#[pin_data]',
     '#[pinned_drop]', 'derive([Maybe]Zeroable)') to use the 'syn'
     parsing library which we introduced last cycle, with better
     diagnostics

   - Implement 'InPlaceWrite' for '&'static mut MaybeUninit'. This
     enables users to use external allocation mechanisms such as
     'static_cell'

   - Support tuple structs in 'derive([Maybe]Zeroable)'

   - Support attributes on fields in '[pin_]init!' (such as
     '#[cfg(...)]')

   - Add a '#[default_error()]' attribute to '[pin_]init!' to
     override the default error (when no '? Error' is specified)

   - Support packed structs in '[pin_]init!' with
     '#[disable_initialized_field_access]'

   - Remove 'try_[pin_]init!' in favor of merging their feature with
     '[pin_]init!'. Update the kernel's own 'try_[pin_]init!' macros to
     use the 'default_error' attribute

   - Correct 'T: Sized' bounds to 'T: ?Sized' in the generated
     'PinnedDrop' check by '#[pin_data]'

  Documentation:

   - Conclude the Rust experiment

  MAINTAINERS:

   - Add "RUST [RUST-ANALYZER]" entry for the rust-analyzer support.
     Tamir and Jesung will take care of it. They have both been active
     around it for a while. The new tree will flow through the Rust one

   - Add Gary as maintainer for "RUST [PIN-INIT]"

   - Update Boqun and Tamir emails to their kernel.org accounts

  And a few other cleanups and improvements"

* tag 'rust-6.20-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: (59 commits)
  rust: safety: introduce `unsafe_precondition_assert!` macro
  rust: add `impl_flags!` macro for defining common bitflag operations
  rust: print: Add pr_*_once macros
  rust: bug: Support DEBUG_BUGVERBOSE_DETAILED option
  rust: print: Add support for calling a function exactly once
  rust: kbuild: deduplicate pin-init flags
  gpu: nova-core: remove imports available via prelude
  rust: clk: replace `kernel::c_str!` with C-Strings
  MAINTAINERS: Update my email address to @kernel.org
  rust: macros: support `#[cfg]` properly in `#[vtable]` macro.
  rust: kunit: use `pin_init::zeroed` instead of custom null value
  rust: macros: rearrange `#[doc(hidden)]` in `module!` macro
  rust: macros: allow arbitrary types to be used in `module!` macro
  rust: macros: convert `#[kunit_tests]` macro to use `syn`
  rust: macros: convert `concat_idents!` to use `syn`
  rust: macros: convert `#[export]` to use `syn`
  rust: macros: use `quote!` for `module!` macro
  rust: macros: use `syn` to parse `module!` macro
  rust: macros: convert `#[vtable]` macro to use `syn`
  rust: macros: use `quote!` from vendored crate
  ...

rust: rbtree: reduce unsafe blocks on pointer derefs

2026-01-19T08:38:10+00:00

Refactors parts of the get() and find_best_match()
traversal logic to minimize the scope of unsafe blocks
and avoid duplicating same safety comments.

One of the removed comments was also misleading:

    // SAFETY: `node` is a non-null node...
    Ordering::Equal => return Some(unsafe { &(*this).value }),

as `node` should have been `this`.

No functional changes intended; this is purely a safety
improvement that reduces the amount of unsafe blocks
while keeping all invariants intact.

[ Alice writes:

    "One consequence of creating a &_ to the bindings::rb_node struct means
    that we assert immutability for the entire struct and not just the
    rb_left/rb_right fields, but I have verified that this is ok."

      - Miguel ]

Signed-off-by: Onur Özkan 
Reviewed-by: Charalampos Mitrodimas 
Reviewed-by: Alice Ryhl 
Link: https://patch.msgid.link/20251113144547.502-1-work@onurozkan.dev
[ Reworded title and replaced `cursor_lower_bound()` with
  `find_best_match()` in message. - Miguel ]
Signed-off-by: Miguel Ojeda

rust: rbtree: fix documentation typo in CursorMut peek_next method

2026-01-04T22:51:35+00:00

The peek_next method's doc comment incorrectly stated it accesses the
"previous" node when it actually accesses the next node.

Fix the documentation to accurately reflect the method's behavior.

Fixes: 98c14e40e07a ("rust: rbtree: add cursor")
Reviewed-by: Alice Ryhl 
Signed-off-by: Hang Shu 
Reported-by: Miguel Ojeda 
Closes: https://github.com/Rust-for-Linux/linux/issues/1205
Cc: stable@vger.kernel.org
Reviewed-by: Gary Guo 
Link: https://patch.msgid.link/20251107093921.3379954-1-m18080292938@163.com
[ Reworded slightly. - Miguel ]
Signed-off-by: Miguel Ojeda

rust: rbtree: fix minor typo in comment

2026-01-04T22:51:35+00:00

Fix a typo in a comment to improve clarity and readability.

Suggested-by: Miguel Ojeda 
Link: https://github.com/Rust-for-Linux/linux/issues/1206
Signed-off-by: Atharv Dubey 
Reviewed-by: Alice Ryhl 
Link: https://patch.msgid.link/20251201165601.31484-1-atharvd440@gmail.com
[ Removed one of the cases that is gone now. Reworded accordingly
  (and to avoid mentioning 'documentation', since it is just
  a comment). - Miguel ]
Signed-off-by: Miguel Ojeda

rust: rbtree: add immutable cursor

2025-11-16T20:56:57+00:00

Sometimes we may need to iterate over, or find an element in a read
only (or read mostly) red-black tree, and in that case we don't need a
mutable reference to the tree, which we'll however have to take to be
able to use the current (mutable) cursor implementation.

This patch adds a simple immutable cursor implementation to RBTree,
which enables us to use an immutable tree reference. The existing
(fully featured) cursor implementation is renamed to CursorMut,
while retaining its functionality.

The only existing user of the [mutable] cursor for RBTrees (binder) is
updated to match the changes.

Signed-off-by: Vitaly Wool 
Reviewed-by: Alice Ryhl 
Link: https://patch.msgid.link/20251014123339.2492210-1-vitaly.wool@konsulko.se
[ Applied `rustfmt`. Added intra-doc link. Fixed unclosed example.
  Fixed docs description. Fixed typo and other formatting nits.
    - Miguel ]
Signed-off-by: Miguel Ojeda

rust: rbtree: simplify finding `current` in `remove_current`

2025-07-14T21:53:35+00:00

The previous version used a verbose `match` to get
`current`, which may be slightly confusing at first
glance.

This change makes it shorter and more clearly expresses
the intent: prefer `next` if available, otherwise fall
back to `prev`.

Signed-off-by: Onur Özkan 
Reviewed-by: Alice Ryhl 
Reviewed-by: Alexandre Courbot 
Link: https://lore.kernel.org/r/20250708075850.25789-1-work@onurozkan.dev
Signed-off-by: Miguel Ojeda

rust: rbtree: add RBTree::is_empty

2025-06-29T16:52:41+00:00

In Rust Binder I need to be able to determine whether a red/black tree
is empty. Thus, add a method for that operation to replace

	rbtree.iter().next().is_none()

This is terrible, so add a method for this purpose. We do not add a
RBTree::len method because computing the number of elements requires
iterating the entire tree, but checking whether it is empty can be done
cheaply.

Signed-off-by: Alice Ryhl 
Reviewed-by: Benno Lossin 
Link: https://lore.kernel.org/r/20250616-rbtree-is-empty-v1-1-61f7cfb012e3@google.com
[ Adjusted title. - Miguel ]
Signed-off-by: Miguel Ojeda

rust: retain pointer mut-ness in `container_of!`

2025-05-28T16:54:09+00:00

Avoid casting the input pointer to `*const _`, allowing the output
pointer to be `*mut` if the input is `*mut`. This allows a number of
`*const` to `*mut` conversions to be removed at the cost of slightly
worse ergonomics when the macro is used with a reference rather than a
pointer; the only example of this was in the macro's own doctest.

Reviewed-by: Benno Lossin 
Reviewed-by: Alice Ryhl 
Signed-off-by: Tamir Duberstein 
Reviewed-by: Andreas Hindborg 
Link: https://lore.kernel.org/r/20250409-container-of-mutness-v1-1-64f472b94534@gmail.com
Signed-off-by: Miguel Ojeda

rust: rbtree: fix comments referring to Box instead of KBox

2025-03-23T18:43:02+00:00

Several safety comments in the RBTree implementation still refer to
"Box::from_raw" and "Box::into_raw", but the code actually uses KBox.
These comments were not updated when the implementation transitioned
from using Box to KBox.

Fixes: 8373147ce496 ("rust: treewide: switch to our kernel `Box` type")
Signed-off-by: Charalampos Mitrodimas 
Reviewed-by: Benno Lossin 
Reviewed-by: Alice Ryhl 
Link: https://lore.kernel.org/r/20250315-rbtree-comment-fixes-v1-1-51f72c420ff0@posteo.net
Signed-off-by: Miguel Ojeda

rust: improve lifetimes markup

2025-03-08T22:04:38+00:00

Improve lifetimes markup; e.g. from:

    /// ... 'a ...

to:

    /// ... `'a` ...

This will make lifetimes display as code span with Markdown and make it
more consistent with rest of the docs.

Link: https://github.com/Rust-for-Linux/linux/issues/1138
Signed-off-by: Borys Tyran 
Link: https://lore.kernel.org/r/20250207142437.112435-1-borys.tyran@protonmail.com
[ Reworded and changed Closes tag to Link. - Miguel ]
Signed-off-by: Miguel Ojeda