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Commit Graph

107 Commits

Author SHA1 Message Date
Linus Torvalds
ec7714e494 Rust changes for v6.16
Toolchain and infrastructure:
 
  - KUnit '#[test]'s:
 
    - Support KUnit-mapped 'assert!' macros.
 
      The support that landed last cycle was very basic, and the
      'assert!' macros panicked since they were the standard library
      ones. Now, they are mapped to the KUnit ones in a similar way to
      how is done for doctests, reusing the infrastructure there.
 
      With this, a failing test like:
 
          #[test]
          fn my_first_test() {
              assert_eq!(42, 43);
          }
 
      will report:
 
          # my_first_test: ASSERTION FAILED at rust/kernel/lib.rs:251
          Expected 42 == 43 to be true, but is false
          # my_first_test.speed: normal
          not ok 1 my_first_test
 
    - Support tests with checked 'Result' return types.
 
      The return value of test functions that return a 'Result' will be
      checked, thus one can now easily catch errors when e.g. using the
      '?' operator in tests.
 
      With this, a failing test like:
 
          #[test]
          fn my_test() -> Result {
              f()?;
              Ok(())
          }
 
      will report:
 
          # my_test: ASSERTION FAILED at rust/kernel/lib.rs:321
          Expected is_test_result_ok(my_test()) to be true, but is false
          # my_test.speed: normal
          not ok 1 my_test
 
    - Add 'kunit_tests' to the prelude.
 
  - Clarify the remaining language unstable features in use.
 
  - Compile 'core' with edition 2024 for Rust >= 1.87.
 
  - Workaround 'bindgen' issue with forward references to 'enum' types.
 
  - objtool: relax slice condition to cover more 'noreturn' functions.
 
  - Use absolute paths in macros referencing 'core' and 'kernel' crates.
 
  - Skip '-mno-fdpic' flag for bindgen in GCC 32-bit arm builds.
 
  - Clean some 'doc_markdown' lint hits -- we may enable it later on.
 
 'kernel' crate:
 
  - 'alloc' module:
 
    - 'Box': support for type coercion, e.g. 'Box<T>' to 'Box<dyn U>' if
      'T' implements 'U'.
 
    - 'Vec': implement new methods (prerequisites for nova-core and
      binder): 'truncate', 'resize', 'clear', 'pop',
      'push_within_capacity' (with new error type 'PushError'),
      'drain_all', 'retain', 'remove' (with new error type
      'RemoveError'), insert_within_capacity' (with new error type
      'InsertError').
 
      In addition, simplify 'push' using 'spare_capacity_mut', split
      'set_len' into 'inc_len' and 'dec_len', add type invariant
      'len <= capacity' and simplify 'truncate' using 'dec_len'.
 
  - 'time' module:
 
    - Morph the Rust hrtimer subsystem into the Rust timekeeping
      subsystem, covering delay, sleep, timekeeping, timers. This new
      subsystem has all the relevant timekeeping C maintainers listed in
      the entry.
 
    - Replace 'Ktime' with 'Delta' and 'Instant' types to represent a
      duration of time and a point in time.
 
    - Temporarily add 'Ktime' to 'hrtimer' module to allow 'hrtimer' to
      delay converting to 'Instant' and 'Delta'.
 
  - 'xarray' module:
 
    - Add a Rust abstraction for the 'xarray' data structure. This
      abstraction allows Rust code to leverage the 'xarray' to store
      types that implement 'ForeignOwnable'. This support is a dependency
      for memory backing feature of the Rust null block driver, which is
      waiting to be merged.
 
    - Set up an entry in 'MAINTAINERS' for the XArray Rust support.
      Patches will go to the new Rust XArray tree and then via the Rust
      subsystem tree for now.
 
    - Allow 'ForeignOwnable' to carry information about the pointed-to
      type. This helps asserting alignment requirements for the pointer
      passed to the foreign language.
 
  - 'container_of!': retain pointer mut-ness and add a compile-time check
    of the type of the first parameter ('$field_ptr').
 
  - Support optional message in 'static_assert!'.
 
  - Add C FFI types (e.g. 'c_int') to the prelude.
 
  - 'str' module: simplify KUnit tests 'format!' macro, convert
    'rusttest' tests into KUnit, take advantage of the '-> Result'
    support in KUnit '#[test]'s.
 
  - 'list' module: add examples for 'List', fix path of 'assert_pinned!'
    (so far unused macro rule).
 
  - 'workqueue' module: remove 'HasWork::OFFSET'.
 
  - 'page' module: add 'inline' attribute.
 
 'macros' crate:
 
  - 'module' macro: place 'cleanup_module()' in '.exit.text' section.
 
 'pin-init' crate:
 
  - Add 'Wrapper<T>' trait for creating pin-initializers for wrapper
    structs with a structurally pinned value such as 'UnsafeCell<T>' or
    'MaybeUninit<T>'.
 
  - Add 'MaybeZeroable' derive macro to try to derive 'Zeroable', but
    not error if not all fields implement it. This is needed to derive
    'Zeroable' for all bindgen-generated structs.
 
  - Add 'unsafe fn cast_[pin_]init()' functions to unsafely change the
    initialized type of an initializer. These are utilized by the
    'Wrapper<T>' implementations.
 
  - Add support for visibility in 'Zeroable' derive macro.
 
  - Add support for 'union's in 'Zeroable' derive macro.
 
  - Upstream dev news: streamline CI, fix some bugs. Add new workflows
    to check if the user-space version and the one in the kernel tree
    have diverged. Use the issues tab [1] to track them, which should
    help folks report and diagnose issues w.r.t. 'pin-init' better.
 
      [1] https://github.com/rust-for-linux/pin-init/issues
 
 Documentation:
 
  - Testing: add docs on the new KUnit '#[test]' tests.
 
  - Coding guidelines: explain that '///' vs. '//' applies to private
    items too. Add section on C FFI types.
 
  - Quick Start guide: update Ubuntu instructions and split them into
    "25.04" and "24.04 LTS and older".
 
 And a few other cleanups and improvements.
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Merge tag 'rust-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

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

   - KUnit '#[test]'s:

      - Support KUnit-mapped 'assert!' macros.

        The support that landed last cycle was very basic, and the
        'assert!' macros panicked since they were the standard library
        ones. Now, they are mapped to the KUnit ones in a similar way to
        how is done for doctests, reusing the infrastructure there.

        With this, a failing test like:

            #[test]
            fn my_first_test() {
                assert_eq!(42, 43);
            }

        will report:

            # my_first_test: ASSERTION FAILED at rust/kernel/lib.rs:251
            Expected 42 == 43 to be true, but is false
            # my_first_test.speed: normal
            not ok 1 my_first_test

      - Support tests with checked 'Result' return types.

        The return value of test functions that return a 'Result' will
        be checked, thus one can now easily catch errors when e.g. using
        the '?' operator in tests.

        With this, a failing test like:

            #[test]
            fn my_test() -> Result {
                f()?;
                Ok(())
            }

        will report:

            # my_test: ASSERTION FAILED at rust/kernel/lib.rs:321
            Expected is_test_result_ok(my_test()) to be true, but is false
            # my_test.speed: normal
            not ok 1 my_test

      - Add 'kunit_tests' to the prelude.

   - Clarify the remaining language unstable features in use.

   - Compile 'core' with edition 2024 for Rust >= 1.87.

   - Workaround 'bindgen' issue with forward references to 'enum' types.

   - objtool: relax slice condition to cover more 'noreturn' functions.

   - Use absolute paths in macros referencing 'core' and 'kernel'
     crates.

   - Skip '-mno-fdpic' flag for bindgen in GCC 32-bit arm builds.

   - Clean some 'doc_markdown' lint hits -- we may enable it later on.

  'kernel' crate:

   - 'alloc' module:

      - 'Box': support for type coercion, e.g. 'Box<T>' to 'Box<dyn U>'
        if 'T' implements 'U'.

      - 'Vec': implement new methods (prerequisites for nova-core and
        binder): 'truncate', 'resize', 'clear', 'pop',
        'push_within_capacity' (with new error type 'PushError'),
        'drain_all', 'retain', 'remove' (with new error type
        'RemoveError'), insert_within_capacity' (with new error type
        'InsertError').

        In addition, simplify 'push' using 'spare_capacity_mut', split
        'set_len' into 'inc_len' and 'dec_len', add type invariant 'len
        <= capacity' and simplify 'truncate' using 'dec_len'.

   - 'time' module:

      - Morph the Rust hrtimer subsystem into the Rust timekeeping
        subsystem, covering delay, sleep, timekeeping, timers. This new
        subsystem has all the relevant timekeeping C maintainers listed
        in the entry.

      - Replace 'Ktime' with 'Delta' and 'Instant' types to represent a
        duration of time and a point in time.

      - Temporarily add 'Ktime' to 'hrtimer' module to allow 'hrtimer'
        to delay converting to 'Instant' and 'Delta'.

   - 'xarray' module:

      - Add a Rust abstraction for the 'xarray' data structure. This
        abstraction allows Rust code to leverage the 'xarray' to store
        types that implement 'ForeignOwnable'. This support is a
        dependency for memory backing feature of the Rust null block
        driver, which is waiting to be merged.

      - Set up an entry in 'MAINTAINERS' for the XArray Rust support.
        Patches will go to the new Rust XArray tree and then via the
        Rust subsystem tree for now.

      - Allow 'ForeignOwnable' to carry information about the pointed-to
        type. This helps asserting alignment requirements for the
        pointer passed to the foreign language.

   - 'container_of!': retain pointer mut-ness and add a compile-time
     check of the type of the first parameter ('$field_ptr').

   - Support optional message in 'static_assert!'.

   - Add C FFI types (e.g. 'c_int') to the prelude.

   - 'str' module: simplify KUnit tests 'format!' macro, convert
     'rusttest' tests into KUnit, take advantage of the '-> Result'
     support in KUnit '#[test]'s.

   - 'list' module: add examples for 'List', fix path of
     'assert_pinned!' (so far unused macro rule).

   - 'workqueue' module: remove 'HasWork::OFFSET'.

   - 'page' module: add 'inline' attribute.

  'macros' crate:

   - 'module' macro: place 'cleanup_module()' in '.exit.text' section.

  'pin-init' crate:

   - Add 'Wrapper<T>' trait for creating pin-initializers for wrapper
     structs with a structurally pinned value such as 'UnsafeCell<T>' or
     'MaybeUninit<T>'.

   - Add 'MaybeZeroable' derive macro to try to derive 'Zeroable', but
     not error if not all fields implement it. This is needed to derive
     'Zeroable' for all bindgen-generated structs.

   - Add 'unsafe fn cast_[pin_]init()' functions to unsafely change the
     initialized type of an initializer. These are utilized by the
     'Wrapper<T>' implementations.

   - Add support for visibility in 'Zeroable' derive macro.

   - Add support for 'union's in 'Zeroable' derive macro.

   - Upstream dev news: streamline CI, fix some bugs. Add new workflows
     to check if the user-space version and the one in the kernel tree
     have diverged. Use the issues tab [1] to track them, which should
     help folks report and diagnose issues w.r.t. 'pin-init' better.

       [1] https://github.com/rust-for-linux/pin-init/issues

  Documentation:

   - Testing: add docs on the new KUnit '#[test]' tests.

   - Coding guidelines: explain that '///' vs. '//' applies to private
     items too. Add section on C FFI types.

   - Quick Start guide: update Ubuntu instructions and split them into
     "25.04" and "24.04 LTS and older".

  And a few other cleanups and improvements"

* tag 'rust-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: (78 commits)
  rust: list: Fix typo `much` in arc.rs
  rust: check type of `$ptr` in `container_of!`
  rust: workqueue: remove HasWork::OFFSET
  rust: retain pointer mut-ness in `container_of!`
  Documentation: rust: testing: add docs on the new KUnit `#[test]` tests
  Documentation: rust: rename `#[test]`s to "`rusttest` host tests"
  rust: str: take advantage of the `-> Result` support in KUnit `#[test]`'s
  rust: str: simplify KUnit tests `format!` macro
  rust: str: convert `rusttest` tests into KUnit
  rust: add `kunit_tests` to the prelude
  rust: kunit: support checked `-> Result`s in KUnit `#[test]`s
  rust: kunit: support KUnit-mapped `assert!` macros in `#[test]`s
  rust: make section names plural
  rust: list: fix path of `assert_pinned!`
  rust: compile libcore with edition 2024 for 1.87+
  rust: dma: add missing Markdown code span
  rust: task: add missing Markdown code spans and intra-doc links
  rust: pci: fix docs related to missing Markdown code spans
  rust: alloc: add missing Markdown code span
  rust: alloc: add missing Markdown code spans
  ...
2025-06-04 21:18:37 -07:00
Patrick Miller
4bf7b97eb3 rust: make section names plural
Clean Rust documentation section headers to use plural names.

Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://github.com/Rust-for-Linux/linux/issues/1110
Signed-off-by: Patrick Miller <paddymills@proton.me>
Link: https://lore.kernel.org/r/20241002022749.390836-1-paddymills@proton.me
[ Removed the `init` one that doesn't apply anymore and
  reworded slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-05-26 18:03:09 +02:00
Miguel Ojeda
06ff274f25 Rust xarray API for v6.16
Introduce Rust support for the `xarray` data structure:
 
  - Add a rust abstraction for the `xarray` data structure. This abstraction
    allows rust code to leverage the `xarray` to store types that implement
    `ForeignOwnable`. This support is a dependency for memory backing feature of
    the rust null block driver, which is waiting to be merged.
 
  - Set up an entry in MAINTAINERS for the xarray rust support. Patches will go
    to the new rust xarray tree and then via the rust subsystem tree for now.
 
 `kernel` crate:
 
  - Allow `ForeignOwnable` to carry information about the pointed-to type. This
    helps asserting alignment requirements for the pointer passed to the foreign
    language.
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Merge tag 'rust-xarray-for-v6.16' of https://github.com/Rust-for-Linux/linux into rust-next

Pull XArray updates from Andreas Hindborg:
 "Introduce Rust support for the 'xarray' data structure:

   - Add a Rust abstraction for the 'xarray' data structure. This
     abstraction allows Rust code to leverage the 'xarray' to store
     types that implement 'ForeignOwnable'. This support is a dependency
     for memory backing feature of the Rust null block driver, which is
     waiting to be merged.

   - Set up an entry in MAINTAINERS for the XArray Rust support. Patches
     will go to the new Rust XArray tree and then via the Rust subsystem
     tree for now.

  'kernel' crate:

   - Allow 'ForeignOwnable' to carry information about the pointed-to
     type. This helps asserting alignment requirements for the pointer
     passed to the foreign language."

* tag 'rust-xarray-for-v6.16' of https://github.com/Rust-for-Linux/linux:
  MAINTAINERS: add entry for Rust XArray API
  rust: xarray: Add an abstraction for XArray
  rust: types: add `ForeignOwnable::PointedTo`
2025-05-18 20:36:56 +02:00
I Hsin Cheng
9520371e3d rust: sync: rcu: Mark Guard methods as inline
Currently the implementation of "Guard" methods are basically wrappers
around rcu's function within kernel. Building the kernel with llvm
18.1.8 on x86_64 machine will generate the following symbols:

$ nm vmlinux | grep ' _R'.*Guard | rustfilt
ffffffff817b6c90 T <kernel::sync::rcu::Guard>::new
ffffffff817b6cb0 T <kernel::sync::rcu::Guard>::unlock
ffffffff817b6cd0 T <kernel::sync::rcu::Guard as core::ops::drop::Drop>::drop
ffffffff817b6c90 T <kernel::sync::rcu::Guard as core::default::Default>::default

These Rust symbols are basically wrappers around functions
"rcu_read_lock" and "rcu_read_unlock". Marking them as inline can
reduce the generation of these symbols, and saves the size of code
generation for 132 bytes.

$ ./scripts/bloat-o-meter vmlinux_old vmlinux_new
(Output is demangled for readability)

add/remove: 0/10 grow/shrink: 0/1 up/down: 0/-132 (-132)
Function                                     old     new   delta
rust_driver_pci::SampleDriver::probe        1041    1034      -7
kernel::sync::rcu::Guard::default             9       -      -9
kernel::sync::rcu::Guard::drop                9       -      -9
kernel::sync::rcu::read_lock                  9       -      -9
kernel::sync::rcu::Guard::unlock              9       -      -9
kernel::sync::rcu::Guard::new                 9       -      -9
__pfx__kernel::sync::rcu::Guard::default     16       -     -16
__pfx__kernel::sync::rcu::Guard::drop        16       -     -16
__pfx__kernel::sync::rcu::read_lock          16       -     -16
__pfx__kernel::sync::rcu::Guard::unlock      16       -     -16
__pfx__kernel::sync::rcu::Guard::new         16       -     -16
Total: Before=23365955, After=23365823, chg -0.00%

Link: https://github.com/Rust-for-Linux/linux/issues/1145
Signed-off-by: I Hsin Cheng <richard120310@gmail.com>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Charalampos Mitrodimas <charmitro@posteo.net>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
2025-05-16 09:00:54 -04:00
Xizhe Yin
86d990c7b6 rust: convert raw URLs to Markdown autolinks in comments
Some comments in Rust files use raw URLs (http://example.com) rather
than Markdown autolinks <URL>. This inconsistency makes the
documentation less uniform and harder to maintain.

This patch converts all remaining raw URLs in Rust code comments to use
the Markdown autolink format, maintaining consistency with the rest of
the codebase which already uses this style.

Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://github.com/Rust-for-Linux/linux/issues/1153
Signed-off-by: Xizhe Yin <xizheyin@smail.nju.edu.cn>
Link: https://lore.kernel.org/r/509F0B66E3C1575D+20250407033441.5567-1-xizheyin@smail.nju.edu.cn
[ Used From form for Signed-off-by. Sorted tags. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-05-12 00:20:25 +02:00
Tamir Duberstein
1a4736c3d8 rust: types: add ForeignOwnable::PointedTo
Allow implementors to specify the foreign pointer type; this exposes
information about the pointed-to type such as its alignment.

This requires the trait to be `unsafe` since it is now possible for
implementors to break soundness by returning a misaligned pointer.

Encoding the pointer type in the trait (and avoiding pointer casts)
allows the compiler to check that implementors return the correct
pointer type. This is preferable to directly encoding the alignment in
the trait using a constant as the compiler would be unable to check it.

Acked-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20250423-rust-xarray-bindings-v19-1-83cdcf11c114@gmail.com
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
2025-05-01 11:35:49 +02:00
Linus Torvalds
4e82c87058 Rust changes for v6.15
Toolchain and infrastructure:
 
  - Extract the 'pin-init' API from the 'kernel' crate and make it into
    a standalone crate.
 
    In order to do this, the contents are rearranged so that they can
    easily be kept in sync with the version maintained out-of-tree that
    other projects have started to use too (or plan to, like QEMU).
 
    This will reduce the maintenance burden for Benno, who will now have
    his own sub-tree, and will simplify future expected changes like the
    move to use 'syn' to simplify the implementation.
 
  - Add '#[test]'-like support based on KUnit.
 
    We already had doctests support based on KUnit, which takes the
    examples in our Rust documentation and runs them under KUnit.
 
    Now, we are adding the beginning of the support for "normal" tests,
    similar to those the '#[test]' tests in userspace Rust. For instance:
 
        #[kunit_tests(my_suite)]
        mod tests {
            #[test]
            fn my_test() {
                assert_eq!(1 + 1, 2);
            }
        }
 
    Unlike with doctests, the 'assert*!'s do not map to the KUnit
    assertion APIs yet.
 
  - Check Rust signatures at compile time for functions called from C by
    name.
 
    In particular, introduce a new '#[export]' macro that can be placed
    in the Rust function definition. It will ensure that the function
    declaration on the C side matches the signature on the Rust function:
 
        #[export]
        pub unsafe extern "C" fn my_function(a: u8, b: i32) -> usize {
            // ...
        }
 
    The macro essentially forces the compiler to compare the types of
    the actual Rust function and the 'bindgen'-processed C signature.
 
    These cases are rare so far. In the future, we may consider
    introducing another tool, 'cbindgen', to generate C headers
    automatically. Even then, having these functions explicitly marked
    may be a good idea anyway.
 
  - Enable the 'raw_ref_op' Rust feature: it is already stable, and
    allows us to use the new '&raw' syntax, avoiding a couple macros.
    After everyone has migrated, we will disallow the macros.
 
  - Pass the correct target to 'bindgen' on Usermode Linux.
 
  - Fix 'rusttest' build in macOS.
 
 'kernel' crate:
 
  - New 'hrtimer' module: add support for setting up intrusive timers
    without allocating when starting the timer. Add support for
    'Pin<Box<_>>', 'Arc<_>', 'Pin<&_>' and 'Pin<&mut _>' as pointer types
    for use with timer callbacks. Add support for setting clock source
    and timer mode.
 
  - New 'dma' module: add a simple DMA coherent allocator abstraction and
    a test sample driver.
 
  - 'list' module: make the linked list 'Cursor' point between elements,
    rather than at an element, which is more convenient to us and allows
    for cursors to empty lists; and document it with examples of how to
    perform common operations with the provided methods.
 
  - 'str' module: implement a few traits for 'BStr' as well as the
    'strip_prefix()' method.
 
  - 'sync' module: add 'Arc::as_ptr'.
 
  - 'alloc' module: add 'Box::into_pin'.
 
  - 'error' module: extend the 'Result' documentation, including a few
    examples on different ways of handling errors, a warning about using
    methods that may panic, and links to external documentation.
 
 'macros' crate:
 
   - 'module' macro: add the 'authors' key to support multiple authors.
     The original key will be kept until everyone has migrated.
 
 Documentation:
 
  - Add error handling sections.
 
 MAINTAINERS:
 
  - Add Danilo Krummrich as reviewer of the Rust "subsystem".
 
  - Add 'RUST [PIN-INIT]' entry with Benno Lossin as maintainer. It has
    its own sub-tree.
 
  - Add sub-tree for 'RUST [ALLOC]'.
 
  - Add 'DMA MAPPING HELPERS DEVICE DRIVER API [RUST]' entry with Abdiel
    Janulgue as primary maintainer. It will go through the sub-tree of
    the 'RUST [ALLOC]' entry.
 
  - Add 'HIGH-RESOLUTION TIMERS [RUST]' entry with Andreas Hindborg as
    maintainer. It has its own sub-tree.
 
 And a few other cleanups and improvements.
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Merge tag 'rust-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

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

   - Extract the 'pin-init' API from the 'kernel' crate and make it into
     a standalone crate.

     In order to do this, the contents are rearranged so that they can
     easily be kept in sync with the version maintained out-of-tree that
     other projects have started to use too (or plan to, like QEMU).

     This will reduce the maintenance burden for Benno, who will now
     have his own sub-tree, and will simplify future expected changes
     like the move to use 'syn' to simplify the implementation.

   - Add '#[test]'-like support based on KUnit.

     We already had doctests support based on KUnit, which takes the
     examples in our Rust documentation and runs them under KUnit.

     Now, we are adding the beginning of the support for "normal" tests,
     similar to those the '#[test]' tests in userspace Rust. For
     instance:

         #[kunit_tests(my_suite)]
         mod tests {
             #[test]
             fn my_test() {
                 assert_eq!(1 + 1, 2);
             }
         }

     Unlike with doctests, the 'assert*!'s do not map to the KUnit
     assertion APIs yet.

   - Check Rust signatures at compile time for functions called from C
     by name.

     In particular, introduce a new '#[export]' macro that can be placed
     in the Rust function definition. It will ensure that the function
     declaration on the C side matches the signature on the Rust
     function:

         #[export]
         pub unsafe extern "C" fn my_function(a: u8, b: i32) -> usize {
             // ...
         }

     The macro essentially forces the compiler to compare the types of
     the actual Rust function and the 'bindgen'-processed C signature.

     These cases are rare so far. In the future, we may consider
     introducing another tool, 'cbindgen', to generate C headers
     automatically. Even then, having these functions explicitly marked
     may be a good idea anyway.

   - Enable the 'raw_ref_op' Rust feature: it is already stable, and
     allows us to use the new '&raw' syntax, avoiding a couple macros.
     After everyone has migrated, we will disallow the macros.

   - Pass the correct target to 'bindgen' on Usermode Linux.

   - Fix 'rusttest' build in macOS.

  'kernel' crate:

   - New 'hrtimer' module: add support for setting up intrusive timers
     without allocating when starting the timer. Add support for
     'Pin<Box<_>>', 'Arc<_>', 'Pin<&_>' and 'Pin<&mut _>' as pointer
     types for use with timer callbacks. Add support for setting clock
     source and timer mode.

   - New 'dma' module: add a simple DMA coherent allocator abstraction
     and a test sample driver.

   - 'list' module: make the linked list 'Cursor' point between
     elements, rather than at an element, which is more convenient to us
     and allows for cursors to empty lists; and document it with
     examples of how to perform common operations with the provided
     methods.

   - 'str' module: implement a few traits for 'BStr' as well as the
     'strip_prefix()' method.

   - 'sync' module: add 'Arc::as_ptr'.

   - 'alloc' module: add 'Box::into_pin'.

   - 'error' module: extend the 'Result' documentation, including a few
     examples on different ways of handling errors, a warning about
     using methods that may panic, and links to external documentation.

  'macros' crate:

   - 'module' macro: add the 'authors' key to support multiple authors.
     The original key will be kept until everyone has migrated.

  Documentation:

   - Add error handling sections.

  MAINTAINERS:

   - Add Danilo Krummrich as reviewer of the Rust "subsystem".

   - Add 'RUST [PIN-INIT]' entry with Benno Lossin as maintainer. It has
     its own sub-tree.

   - Add sub-tree for 'RUST [ALLOC]'.

   - Add 'DMA MAPPING HELPERS DEVICE DRIVER API [RUST]' entry with
     Abdiel Janulgue as primary maintainer. It will go through the
     sub-tree of the 'RUST [ALLOC]' entry.

   - Add 'HIGH-RESOLUTION TIMERS [RUST]' entry with Andreas Hindborg as
     maintainer. It has its own sub-tree.

  And a few other cleanups and improvements"

* tag 'rust-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: (71 commits)
  rust: dma: add `Send` implementation for `CoherentAllocation`
  rust: macros: fix `make rusttest` build on macOS
  rust: block: refactor to use `&raw mut`
  rust: enable `raw_ref_op` feature
  rust: uaccess: name the correct function
  rust: rbtree: fix comments referring to Box instead of KBox
  rust: hrtimer: add maintainer entry
  rust: hrtimer: add clocksource selection through `ClockId`
  rust: hrtimer: add `HrTimerMode`
  rust: hrtimer: implement `HrTimerPointer` for `Pin<Box<T>>`
  rust: alloc: add `Box::into_pin`
  rust: hrtimer: implement `UnsafeHrTimerPointer` for `Pin<&mut T>`
  rust: hrtimer: implement `UnsafeHrTimerPointer` for `Pin<&T>`
  rust: hrtimer: add `hrtimer::ScopedHrTimerPointer`
  rust: hrtimer: add `UnsafeHrTimerPointer`
  rust: hrtimer: allow timer restart from timer handler
  rust: str: implement `strip_prefix` for `BStr`
  rust: str: implement `AsRef<BStr>` for `[u8]` and `BStr`
  rust: str: implement `Index` for `BStr`
  rust: str: implement `PartialEq` for `BStr`
  ...
2025-03-30 17:03:26 -07:00
Miguel Ojeda
e6ea10d5db Rust hrtimer API for v6.15
Introduce Rust support for the `hrtimer` subsystem:
 
  - Add a way to use the `hrtimer` subsystem from Rust. Rust code can now set up
    intrusive timers without allocating when starting the timer.
 
  - Add support for `Pin<Box<_>>`, `Arc<_>`, `Pin<&_>` and `Pin<&mut _>` as
    pointer types for use with timer callbacks.
 
  - Add support for setting clock source and timer mode.
 
 `kernel` crate:
 
  - Add `Arc::as_ptr` for converting an `Arc` to a raw pointer. This is a
    dependency for the `hrtimer` API.
 
  - Add `Box::into_pin` for converting a `Box<_>` into a `Pin<Box<_>>` to align
    with Rust `alloc`. This is a dependency for the `hrtimer` API.
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Merge tag 'rust-hrtimer-for-v6.15-v3' of https://github.com/Rust-for-Linux/linux into rust-next

Pull rust-hrtimer updates from Andreas Hindborg:
 "Introduce Rust support for the 'hrtimer' subsystem:

   - Add a way to use the 'hrtimer' subsystem from Rust. Rust code can
     now set up intrusive timers without allocating when starting the
     timer.

   - Add support for 'Pin<Box<_>>', 'Arc<_>', 'Pin<&_>' and
     'Pin<&mut _>' as pointer types for use with timer callbacks.

   - Add support for setting clock source and timer mode.

  'kernel' crate:

   - Add 'Arc::as_ptr' for converting an 'Arc' to a raw pointer. This is
     a dependency for the 'hrtimer' API.

   - Add 'Box::into_pin' for converting a 'Box<_>' into a 'Pin<Box<_>>'
     to align with Rust 'alloc'. This is a dependency for the 'hrtimer'
     API."

* tag 'rust-hrtimer-for-v6.15-v3' of https://github.com/Rust-for-Linux/linux:
  rust: hrtimer: add maintainer entry
  rust: hrtimer: add clocksource selection through `ClockId`
  rust: hrtimer: add `HrTimerMode`
  rust: hrtimer: implement `HrTimerPointer` for `Pin<Box<T>>`
  rust: alloc: add `Box::into_pin`
  rust: hrtimer: implement `UnsafeHrTimerPointer` for `Pin<&mut T>`
  rust: hrtimer: implement `UnsafeHrTimerPointer` for `Pin<&T>`
  rust: hrtimer: add `hrtimer::ScopedHrTimerPointer`
  rust: hrtimer: add `UnsafeHrTimerPointer`
  rust: hrtimer: allow timer restart from timer handler
  rust: hrtimer: implement `HrTimerPointer` for `Arc`
  rust: sync: add `Arc::as_ptr`
  rust: hrtimer: introduce hrtimer support
2025-03-25 23:41:14 +01:00
Linus Torvalds
23608993bb Locking changes for v6.15:
Locking primitives:
 
     - Micro-optimize percpu_{,try_}cmpxchg{64,128}_op() and {,try_}cmpxchg{64,128}
       on x86 (Uros Bizjak)
 
     - mutexes: extend debug checks in mutex_lock() (Yunhui Cui)
 
     - Misc cleanups (Uros Bizjak)
 
   Lockdep:
 
     - Fix might_fault() lockdep check of current->mm->mmap_lock (Peter Zijlstra)
 
     - Don't disable interrupts on RT in disable_irq_nosync_lockdep.*()
       (Sebastian Andrzej Siewior)
 
     - Disable KASAN instrumentation of lockdep.c (Waiman Long)
 
     - Add kasan_check_byte() check in lock_acquire() (Waiman Long)
 
     - Misc cleanups (Sebastian Andrzej Siewior)
 
   Rust runtime integration:
 
     - Use Pin for all LockClassKey usages (Mitchell Levy)
     - sync: Add accessor for the lock behind a given guard (Alice Ryhl)
     - sync: condvar: Add wait_interruptible_freezable() (Alice Ryhl)
     - sync: lock: Add an example for Guard:: Lock_ref() (Boqun Feng)
 
   Split-lock detection feature (x86):
 
     - Fix warning mode with disabled mitigation mode (Maksim Davydov)
 
   Locking events:
 
     - Add locking events for rtmutex slow paths (Waiman Long)
     - Add locking events for lockdep (Waiman Long)
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "Locking primitives:
   - Micro-optimize percpu_{,try_}cmpxchg{64,128}_op() and
     {,try_}cmpxchg{64,128} on x86 (Uros Bizjak)
   - mutexes: extend debug checks in mutex_lock() (Yunhui Cui)
   - Misc cleanups (Uros Bizjak)

  Lockdep:
   - Fix might_fault() lockdep check of current->mm->mmap_lock (Peter
     Zijlstra)
   - Don't disable interrupts on RT in disable_irq_nosync_lockdep.*()
     (Sebastian Andrzej Siewior)
   - Disable KASAN instrumentation of lockdep.c (Waiman Long)
   - Add kasan_check_byte() check in lock_acquire() (Waiman Long)
   - Misc cleanups (Sebastian Andrzej Siewior)

  Rust runtime integration:
   - Use Pin for all LockClassKey usages (Mitchell Levy)
   - sync: Add accessor for the lock behind a given guard (Alice Ryhl)
   - sync: condvar: Add wait_interruptible_freezable() (Alice Ryhl)
   - sync: lock: Add an example for Guard:: Lock_ref() (Boqun Feng)

  Split-lock detection feature (x86):
   - Fix warning mode with disabled mitigation mode (Maksim Davydov)

  Locking events:
   - Add locking events for rtmutex slow paths (Waiman Long)
   - Add locking events for lockdep (Waiman Long)"

* tag 'locking-core-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  lockdep: Remove disable_irq_lockdep()
  lockdep: Don't disable interrupts on RT in disable_irq_nosync_lockdep.*()
  rust: lockdep: Use Pin for all LockClassKey usages
  rust: sync: condvar: Add wait_interruptible_freezable()
  rust: sync: lock: Add an example for Guard:: Lock_ref()
  rust: sync: Add accessor for the lock behind a given guard
  locking/lockdep: Add kasan_check_byte() check in lock_acquire()
  locking/lockdep: Disable KASAN instrumentation of lockdep.c
  locking/lock_events: Add locking events for lockdep
  locking/lock_events: Add locking events for rtmutex slow paths
  x86/split_lock: Fix the delayed detection logic
  lockdep/mm: Fix might_fault() lockdep check of current->mm->mmap_lock
  x86/locking: Remove semicolon from "lock" prefix
  locking/mutex: Add MUTEX_WARN_ON() into fast path
  x86/locking: Use asm_inline for {,try_}cmpxchg{64,128} emulations
  x86/locking: Use ALT_OUTPUT_SP() for percpu_{,try_}cmpxchg{64,128}_op()
2025-03-24 20:55:03 -07:00
Benno Lossin
dbd5058ba6 rust: make pin-init its own crate
Rename relative paths inside of the crate to still refer to the same
items, also rename paths inside of the kernel crate and adjust the build
system to build the crate.

[ Remove the `expect` (and thus the `lint_reasons` feature) since
  the tree now uses `quote!` from `rust/macros/export.rs`. Remove the
  `TokenStream` import removal, since it is now used as well.

  In addition, temporarily (i.e. just for this commit) use an `--extern
  force:alloc` to prevent an unknown `new_uninit` error in the `rustdoc`
  target. For context, please see a similar case in:

      https://lore.kernel.org/lkml/20240422090644.525520-1-ojeda@kernel.org/

  And adjusted the message above. - Miguel ]

Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Fiona Behrens <me@kloenk.dev>
Tested-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://lore.kernel.org/r/20250308110339.2997091-16-benno.lossin@proton.me
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-16 21:59:19 +01:00
Benno Lossin
129e97be8e rust: pin-init: fix documentation links
Before switching to compile the `pin-init` crate directly, change
any links that would be invalid to links that are valid both before and
after the switch.

Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Fiona Behrens <me@kloenk.dev>
Tested-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://lore.kernel.org/r/20250308110339.2997091-12-benno.lossin@proton.me
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-16 21:59:19 +01:00
Benno Lossin
114ca41fe7 rust: pin-init: move InPlaceInit and impls of InPlaceWrite into the kernel crate
In order to make pin-init a standalone crate, move kernel-specific code
directly into the kernel crate. This includes the `InPlaceInit<T>`
trait, its implementations and the implementations of `InPlaceWrite` for
`Arc` and `UniqueArc`. All of these use the kernel's error type which
will become unavailable in pin-init.

Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Fiona Behrens <me@kloenk.dev>
Tested-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://lore.kernel.org/r/20250308110339.2997091-9-benno.lossin@proton.me
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-16 21:59:18 +01:00
Andreas Hindborg
a0c6fa8b8a rust: sync: add Arc::as_ptr
Add a method to get a pointer to the data contained in an `Arc`.

Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20250309-hrtimer-v3-v6-12-rc2-v12-2-73586e2bd5f1@kernel.org
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
2025-03-11 21:00:42 +01:00
Borys Tyran
cd1ed11a67 rust: improve lifetimes markup
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 <borys.tyran@protonmail.com>
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 <ojeda@kernel.org>
2025-03-08 23:04:38 +01:00
Mitchell Levy
f73ca66f0d rust: lockdep: Use Pin for all LockClassKey usages
Reintroduce dynamically-allocated LockClassKeys such that they are
automatically (de)registered. Require that all usages of LockClassKeys
ensure that they are Pin'd.

Currently, only `'static` LockClassKeys are supported, so Pin is
redundant. However, it is intended that dynamically-allocated
LockClassKeys will eventually be supported, so using Pin from the outset
will make that change simpler.

Closes: https://github.com/Rust-for-Linux/linux/issues/1102
Suggested-by: Benno Lossin <benno.lossin@proton.me>
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Mitchell Levy <levymitchell0@gmail.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20250307232717.1759087-12-boqun.feng@gmail.com
2025-03-08 00:55:04 +01:00
Alice Ryhl
70b9c8563c rust: sync: condvar: Add wait_interruptible_freezable()
To support waiting for a `CondVar` as a freezable process, add a
wait_interruptible_freezable() function.

Binder needs this function in the appropriate places to freeze a process
where some of its threads are blocked on the Binder driver.

[ Boqun: Cleaned up the changelog and documentation. ]

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250307232717.1759087-10-boqun.feng@gmail.com
2025-03-08 00:55:04 +01:00
Boqun Feng
c2849afafd rust: sync: lock: Add an example for Guard:: Lock_ref()
To provide examples on usage of `Guard::lock_ref()` along with the unit
test, an "assert a lock is held by a guard" example is added.

(Also apply feedback from Benno.)

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20250223072114.3715-1-boqun.feng@gmail.com
Link: https://lore.kernel.org/r/20250307232717.1759087-9-boqun.feng@gmail.com
2025-03-08 00:55:04 +01:00
Alice Ryhl
8f65291dae rust: sync: Add accessor for the lock behind a given guard
In order to assert a particular `Guard` is associated with a particular
`Lock`, add an accessor to obtain a reference to the underlying `Lock`
of a `Guard`.

Binder needs this assertion to ensure unsafe list operations are done
with the correct lock held.

[Boqun: Capitalize the title and reword the commit log]

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Fiona Behrens <me@kloenk.dev>
Link: https://lore.kernel.org/r/20250205-guard-get-lock-v2-1-ba32a8c1d5b7@google.com
Link: https://lore.kernel.org/r/20250307232717.1759087-8-boqun.feng@gmail.com
2025-03-08 00:55:04 +01:00
Alban Kurti
50c3e77eb3 rust: sync: add missing newline in locked_by log example
The pr_info! example in rust/kernel/sync/locked_by.rs was missing
a newline. This patch appends the missing newline to ensure
that log messages for locked resources display correctly.

Fixes: 7b1f55e3a9 ("rust: sync: introduce `LockedBy`")
Reported-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://github.com/Rust-for-Linux/linux/issues/1139
Signed-off-by: Alban Kurti <kurti@invicto.ai>
Link: https://lore.kernel.org/r/20250206-printing_fix-v3-4-a85273b501ae@invicto.ai
[ Replaced Closes with Link since it fixes part of the issue. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-06 20:44:06 +01:00
Linus Torvalds
2ab002c755 Driver core and debugfs updates
Here is the big set of driver core and debugfs updates for 6.14-rc1.
 It's coming late in the merge cycle as there are a number of merge
 conflicts with your tree now, and I wanted to make sure they were
 working properly.  To resolve them, look in linux-next, and I will send
 the "fixup" patch as a response to the pull request.
 
 Included in here is a bunch of driver core, PCI, OF, and platform rust
 bindings (all acked by the different subsystem maintainers), hence the
 merge conflict with the rust tree, and some driver core api updates to
 mark things as const, which will also require some fixups due to new
 stuff coming in through other trees in this merge window.
 
 There are also a bunch of debugfs updates from Al, and there is at least
 one user that does have a regression with these, but Al is working on
 tracking down the fix for it.  In my use (and everyone else's linux-next
 use), it does not seem like a big issue at the moment.
 
 Here's a short list of the things in here:
   - driver core bindings for PCI, platform, OF, and some i/o functions.
     We are almost at the "write a real driver in rust" stage now,
     depending on what you want to do.
   - misc device rust bindings and a sample driver to show how to use
     them
   - debugfs cleanups in the fs as well as the users of the fs api for
     places where drivers got it wrong or were unnecessarily doing things
     in complex ways.
   - driver core const work, making more of the api take const * for
     different parameters to make the rust bindings easier overall.
   - other small fixes and updates
 
 All of these have been in linux-next with all of the aforementioned
 merge conflicts, and the one debugfs issue, which looks to be resolved
 "soon".
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core and debugfs updates from Greg KH:
 "Here is the big set of driver core and debugfs updates for 6.14-rc1.

  Included in here is a bunch of driver core, PCI, OF, and platform rust
  bindings (all acked by the different subsystem maintainers), hence the
  merge conflict with the rust tree, and some driver core api updates to
  mark things as const, which will also require some fixups due to new
  stuff coming in through other trees in this merge window.

  There are also a bunch of debugfs updates from Al, and there is at
  least one user that does have a regression with these, but Al is
  working on tracking down the fix for it. In my use (and everyone
  else's linux-next use), it does not seem like a big issue at the
  moment.

  Here's a short list of the things in here:

   - driver core rust bindings for PCI, platform, OF, and some i/o
     functions.

     We are almost at the "write a real driver in rust" stage now,
     depending on what you want to do.

   - misc device rust bindings and a sample driver to show how to use
     them

   - debugfs cleanups in the fs as well as the users of the fs api for
     places where drivers got it wrong or were unnecessarily doing
     things in complex ways.

   - driver core const work, making more of the api take const * for
     different parameters to make the rust bindings easier overall.

   - other small fixes and updates

  All of these have been in linux-next with all of the aforementioned
  merge conflicts, and the one debugfs issue, which looks to be resolved
  "soon""

* tag 'driver-core-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (95 commits)
  rust: device: Use as_char_ptr() to avoid explicit cast
  rust: device: Replace CString with CStr in property_present()
  devcoredump: Constify 'struct bin_attribute'
  devcoredump: Define 'struct bin_attribute' through macro
  rust: device: Add property_present()
  saner replacement for debugfs_rename()
  orangefs-debugfs: don't mess with ->d_name
  octeontx2: don't mess with ->d_parent or ->d_parent->d_name
  arm_scmi: don't mess with ->d_parent->d_name
  slub: don't mess with ->d_name
  sof-client-ipc-flood-test: don't mess with ->d_name
  qat: don't mess with ->d_name
  xhci: don't mess with ->d_iname
  mtu3: don't mess wiht ->d_iname
  greybus/camera - stop messing with ->d_iname
  mediatek: stop messing with ->d_iname
  netdevsim: don't embed file_operations into your structs
  b43legacy: make use of debugfs_get_aux()
  b43: stop embedding struct file_operations into their objects
  carl9170: stop embedding file_operations into their objects
  ...
2025-01-28 12:25:12 -08:00
Linus Torvalds
e3610441d1 Rust changes for v6.14
Toolchain and infrastructure:
 
  - Finish the move to custom FFI integer types started in the previous
    cycle and finally map 'long' to 'isize' and 'char' to 'u8'. Do a few
    cleanups on top thanks to that.
 
  - Start to use 'derive(CoercePointee)' on Rust >= 1.84.0.
 
    This is a major milestone on the path to build the kernel using only
    stable Rust features. In particular, previously we were using the
    unstable features 'coerce_unsized', 'dispatch_from_dyn' and 'unsize',
    and now we will use the new 'derive_coerce_pointee' one, which is on
    track to stabilization. This new feature is a macro that essentially
    expands into code that internally uses the unstable features that we
    were using before, without having to expose those.
 
    With it, stable Rust users, including the kernel, will be able to
    build custom smart pointers that work with trait objects, e.g.:
 
        fn f(p: &Arc<dyn Display>) {
            pr_info!("{p}\n");
        }
 
        let a: Arc<dyn Display> = Arc::new(42i32, GFP_KERNEL)?;
        let b: Arc<dyn Display> = Arc::new("hello there", GFP_KERNEL)?;
 
        f(&a); // Prints "42".
        f(&b); // Prints "hello there".
 
    Together with the 'arbitrary_self_types' feature that we started
    using in the previous cycle, using our custom smart pointers like
    'Arc' will eventually only rely in stable Rust.
 
  - Introduce 'PROCMACROLDFLAGS' environment variable to allow to link
    Rust proc macros using different flags than those used for linking
    Rust host programs (e.g. when 'rustc' uses a different C library
    than the host programs' one), which Android needs.
 
  - Help kernel builds under macOS with Rust enabled by accomodating
    other naming conventions for dynamic libraries (i.e. '.so' vs.
    '.dylib') which are used for Rust procedural macros. The actual
    support for macOS (i.e. the rest of the pieces needed) is provided
    out-of-tree by others, following the policy used for other parts of
    the kernel by Kbuild.
 
  - Run Clippy for 'rusttest' code too and clean the bits it spotted.
 
  - Provide Clippy with the minimum supported Rust version to improve
    the suggestions it gives.
 
  - Document 'bindgen' 0.71.0 regression.
 
 'kernel' crate:
 
  - 'build_error!': move users of the hidden function to the documented
    macro, prevent such uses in the future by moving the function
    elsewhere and add the macro to the prelude.
 
  - 'types' module: add improved version of 'ForeignOwnable::borrow_mut'
    (which was removed in the past since it was problematic); change
    'ForeignOwnable' pointer type to '*mut'.
 
  - 'alloc' module: implement 'Display' for 'Box' and align the 'Debug'
    implementation to it; add example (doctest) for 'ArrayLayout::new()'.
 
  - 'sync' module: document 'PhantomData' in 'Arc'; use
    'NonNull::new_unchecked' in 'ForeignOwnable for Arc' impl.
 
  - 'uaccess' module: accept 'Vec's with different allocators in
    'UserSliceReader::read_all'.
 
  - 'workqueue' module: enable run-testing a couple more doctests.
 
  - 'error' module: simplify 'from_errno()'.
 
  - 'block' module: fix formatting in code documentation (a lint to catch
    these is being implemented).
 
  - Avoid 'unwrap()'s in doctests, which also improves the examples by
    showing how kernel code is supposed to be written.
 
  - Avoid 'as' casts with 'cast{,_mut}' calls which are a bit safer.
 
 And a few other cleanups.
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Merge tag 'rust-6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

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

   - Finish the move to custom FFI integer types started in the previous
     cycle and finally map 'long' to 'isize' and 'char' to 'u8'. Do a
     few cleanups on top thanks to that.

   - Start to use 'derive(CoercePointee)' on Rust >= 1.84.0.

     This is a major milestone on the path to build the kernel using
     only stable Rust features. In particular, previously we were using
     the unstable features 'coerce_unsized', 'dispatch_from_dyn' and
     'unsize', and now we will use the new 'derive_coerce_pointee' one,
     which is on track to stabilization. This new feature is a macro
     that essentially expands into code that internally uses the
     unstable features that we were using before, without having to
     expose those.

     With it, stable Rust users, including the kernel, will be able to
     build custom smart pointers that work with trait objects, e.g.:

         fn f(p: &Arc<dyn Display>) {
             pr_info!("{p}\n");
         }

         let a: Arc<dyn Display> = Arc::new(42i32, GFP_KERNEL)?;
         let b: Arc<dyn Display> = Arc::new("hello there", GFP_KERNEL)?;

         f(&a); // Prints "42".
         f(&b); // Prints "hello there".

     Together with the 'arbitrary_self_types' feature that we started
     using in the previous cycle, using our custom smart pointers like
     'Arc' will eventually only rely in stable Rust.

   - Introduce 'PROCMACROLDFLAGS' environment variable to allow to link
     Rust proc macros using different flags than those used for linking
     Rust host programs (e.g. when 'rustc' uses a different C library
     than the host programs' one), which Android needs.

   - Help kernel builds under macOS with Rust enabled by accomodating
     other naming conventions for dynamic libraries (i.e. '.so' vs.
     '.dylib') which are used for Rust procedural macros. The actual
     support for macOS (i.e. the rest of the pieces needed) is provided
     out-of-tree by others, following the policy used for other parts of
     the kernel by Kbuild.

   - Run Clippy for 'rusttest' code too and clean the bits it spotted.

   - Provide Clippy with the minimum supported Rust version to improve
     the suggestions it gives.

   - Document 'bindgen' 0.71.0 regression.

  'kernel' crate:

   - 'build_error!': move users of the hidden function to the documented
     macro, prevent such uses in the future by moving the function
     elsewhere and add the macro to the prelude.

   - 'types' module: add improved version of 'ForeignOwnable::borrow_mut'
     (which was removed in the past since it was problematic); change
     'ForeignOwnable' pointer type to '*mut'.

   - 'alloc' module: implement 'Display' for 'Box' and align the 'Debug'
     implementation to it; add example (doctest) for 'ArrayLayout::new()'

   - 'sync' module: document 'PhantomData' in 'Arc'; use
     'NonNull::new_unchecked' in 'ForeignOwnable for Arc' impl.

   - 'uaccess' module: accept 'Vec's with different allocators in
     'UserSliceReader::read_all'.

   - 'workqueue' module: enable run-testing a couple more doctests.

   - 'error' module: simplify 'from_errno()'.

   - 'block' module: fix formatting in code documentation (a lint to catch
     these is being implemented).

   - Avoid 'unwrap()'s in doctests, which also improves the examples by
     showing how kernel code is supposed to be written.

   - Avoid 'as' casts with 'cast{,_mut}' calls which are a bit safer.

  And a few other cleanups"

* tag 'rust-6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: (32 commits)
  kbuild: rust: add PROCMACROLDFLAGS
  rust: uaccess: generalize userSliceReader to support any Vec
  rust: kernel: add improved version of `ForeignOwnable::borrow_mut`
  rust: kernel: reorder `ForeignOwnable` items
  rust: kernel: change `ForeignOwnable` pointer to mut
  rust: arc: split unsafe block, add missing comment
  rust: types: avoid `as` casts
  rust: arc: use `NonNull::new_unchecked`
  rust: use derive(CoercePointee) on rustc >= 1.84.0
  rust: alloc: add doctest for `ArrayLayout::new()`
  rust: init: update `stack_try_pin_init` examples
  rust: error: import `kernel`'s `LayoutError` instead of `core`'s
  rust: str: replace unwraps with question mark operators
  rust: page: remove unnecessary helper function from doctest
  rust: rbtree: remove unwrap in asserts
  rust: init: replace unwraps with question mark operators
  rust: use host dylib naming convention to support macOS
  rust: add `build_error!` to the prelude
  rust: kernel: move `build_error` hidden function to prevent mistakes
  rust: use the `build_error!` macro, not the hidden function
  ...
2025-01-21 17:48:03 -08:00
Alice Ryhl
c27e705cb2 rust: kernel: add improved version of ForeignOwnable::borrow_mut
Previously, the `ForeignOwnable` trait had a method called `borrow_mut`
that was intended to provide mutable access to the inner value. However,
the method accidentally made it possible to change the address of the
object being modified, which usually isn't what we want. (And when we
want that, it can be done by calling `from_foreign` and `into_foreign`,
like how the old `borrow_mut` was implemented.)

In this patch, we introduce an alternate definition of `borrow_mut` that
solves the previous problem. Conceptually, given a pointer type `P` that
implements `ForeignOwnable`, the `borrow_mut` method gives you the same
kind of access as an `&mut P` would, except that it does not let you
change the pointer `P` itself.

This is analogous to how the existing `borrow` method provides the same
kind of access to the inner value as an `&P`.

Note that for types like `Arc`, having an `&mut Arc<T>` only gives you
immutable access to the inner `T`. This is because mutable references
assume exclusive access, but there might be other handles to the same
reference counted value, so the access isn't exclusive. The `Arc` type
implements this by making `borrow_mut` return the same type as `borrow`.

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20241120-borrow-mut-v6-6-80dbadd00951@gmail.com
[ Updated to `crate::ffi::`. Reworded title slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-01-13 23:46:07 +01:00
Tamir Duberstein
c6b97538c2 rust: kernel: reorder ForeignOwnable items
`{into,from}_foreign` before `borrow` is slightly more logical.

This removes an inconsistency with `kbox.rs` which already uses this
ordering.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Link: https://lore.kernel.org/r/20241120-borrow-mut-v6-5-80dbadd00951@gmail.com
[ Reworded title slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-01-13 23:45:54 +01:00
Tamir Duberstein
14686571a9 rust: kernel: change ForeignOwnable pointer to mut
It is slightly more convenient to operate on mut pointers, and this also
properly conveys the desired ownership semantics of the trait.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20241120-borrow-mut-v6-4-80dbadd00951@gmail.com
[ Reworded title slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-01-13 23:45:31 +01:00
Tamir Duberstein
5d385a356f rust: arc: split unsafe block, add missing comment
The new SAFETY comment style is taken from existing comments in `deref`
and `drop.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Link: https://lore.kernel.org/r/20241120-borrow-mut-v6-3-80dbadd00951@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-01-13 23:45:31 +01:00
Tamir Duberstein
aa991a2a81 rust: types: avoid as casts
Replace `as` casts with `cast{,_mut}` calls which are a bit safer.

In one instance, remove an unnecessary `as` cast without replacement.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20241120-borrow-mut-v6-2-80dbadd00951@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-01-13 23:45:30 +01:00
Tamir Duberstein
c6340da3d2 rust: arc: use NonNull::new_unchecked
There is no need to check (and panic on violations of) the safety
requirements on `ForeignOwnable` functions. Avoiding the check is
consistent with the implementation of `ForeignOwnable` for `Box`.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Link: https://lore.kernel.org/r/20241120-borrow-mut-v6-1-80dbadd00951@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-01-13 23:45:30 +01:00
Xiangfei Ding
47cb6bf786 rust: use derive(CoercePointee) on rustc >= 1.84.0
The `kernel` crate relies on both `coerce_unsized` and `dispatch_from_dyn`
unstable features.

Alice Ryhl has proposed [1] the introduction of the unstable macro
`SmartPointer` to reduce such dependence, along with a RFC patch [2].
Since Rust 1.81.0 this macro, later renamed to `CoercePointee` in
Rust 1.84.0 [3], has been fully implemented with the naming discussion
resolved.

This feature is now on track to stabilization in the language.
In order to do so, we shall start using this macro in the `kernel` crate
to prove the functionality and utility of the macro as the justification
of its stabilization.

This patch makes this switch in such a way that the crate remains
backward compatible with older Rust compiler versions,
via the new Kconfig option `RUSTC_HAS_COERCE_POINTEE`.

A minimal demonstration example is added to the
`samples/rust/rust_print_main.rs` module.

Link: https://rust-lang.github.io/rfcs/3621-derive-smart-pointer.html [1]
Link: https://lore.kernel.org/all/20240823-derive-smart-pointer-v1-1-53769cd37239@google.com/ [2]
Link: https://github.com/rust-lang/rust/pull/131284 [3]
Signed-off-by: Xiangfei Ding <dingxiangfei2009@gmail.com>
Reviewed-by: Fiona Behrens <me@kloenk.dev>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20241203205050.679106-2-dingxiangfei2009@gmail.com
[ Fixed version to 1.84. Renamed option to `RUSTC_HAS_COERCE_POINTEE`
  to match `CC_HAS_*` ones. Moved up new config option, closer to the
  `CC_HAS_*` ones. Simplified Kconfig line. Fixed typos and slightly
  reworded example and commit. Added Link to PR. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-01-13 23:45:30 +01:00
Wedson Almeida Filho
5115820729 rust: add rcu abstraction
Add a simple abstraction to guard critical code sections with an rcu
read lock.

Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Co-developed-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Tested-by: Dirk Behme <dirk.behme@de.bosch.com>
Tested-by: Fabien Parent <fabien.parent@linaro.org>
Link: https://lore.kernel.org/r/20241219170425.12036-5-dakr@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-20 17:19:26 +01:00
Lyude Paul
fbd7a5a035 rust: sync: Add lock::Backend::assert_is_held()
Since we've exposed Lock::from_raw() and Guard::new() publically, we
want to be able to make sure that we assert that a lock is actually held
when constructing a Guard for it to handle instances of unsafe
Guard::new() calls outside of our lock module.

Hence add a new method assert_is_held() to Backend, which uses lockdep
to check whether or not a lock has been acquired. When lockdep is
disabled, this has no overhead.

[Boqun: Resolve the conflicts with exposing Guard::new(), reword the
 commit log a bit and format "unsafe { <statement>; }" into "unsafe {
 <statement> }" for the consistency. ]

Signed-off-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20241125204139.656801-1-lyude@redhat.com
2024-12-19 14:04:42 -08:00
Lyude Paul
eb5ccb0382 rust: sync: Add SpinLockGuard type alias
A simple helper alias for code that needs to deal with Guard types returned
from SpinLocks.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20241120222742.2490495-3-lyude@redhat.com
2024-12-19 14:04:42 -08:00
Lyude Paul
37624dde47 rust: sync: Add MutexGuard type alias
A simple helper alias for code that needs to deal with Guard types returned
from Mutexes.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20241120222742.2490495-2-lyude@redhat.com
2024-12-19 14:04:42 -08:00
Lyude Paul
daa03fe50e rust: sync: Make Guard::new() public
Since we added a `Lock::from_raw()` function previously, it makes sense
to also introduce an interface for creating a `Guard` from a reference
to a `Lock` for instances where we've derived the `Lock` from a raw
pointer and know that the lock is already acquired, there are such
usages in KMS API.

[Boqun: Add backquotes to type names, reformat the commit log, reword a
 bit on the usage of KMS API]

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Filipe Xavier <felipe_life@live.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20241119231146.2298971-3-lyude@redhat.com
2024-12-19 14:04:42 -08:00
Lyude Paul
15abc88057 rust: sync: Add Lock::from_raw() for Lock<(), B>
The KMS bindings [1] have a few bindings that require manually acquiring
specific locks before calling certain functions. At the moment though,
the only way of acquiring these locks in bindings is to simply call the
C locking functions directly - since said locks are not initialized on
the Rust side of things.

However - if we add `#[repr(C)]` to `Lock<(), B>`, then given `()` is a
ZST - `Lock<(), B>` becomes equivalent in data layout to its inner
`B::State` type. Since locks in C don't have data explicitly associated
with them anyway, we can take advantage of this to add a
`Lock::from_raw()` function that can translate a raw pointer to
`B::State` into its proper `Lock<(), B>` equivalent. This lets us simply
acquire a reference to the lock in question and work with it like it was
initialized on the Rust side of things, allowing us to use less unsafe
code to implement bindings with lock requirements.

[Boqun: Use "Link:" instead of a URL and format the commit log]

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://patchwork.freedesktop.org/series/131522/ [1]
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20241119231146.2298971-2-lyude@redhat.com
2024-12-19 14:04:42 -08:00
Tamir Duberstein
2dde1c8b04 rust: sync: document PhantomData in Arc
Add a comment explaining the relevant semantics of `PhantomData`. This
should help future readers who may, as I did, assume that this field is
redundant at first glance.

Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20241107-simplify-arc-v2-1-7256e638aac1@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-12-18 00:37:21 +01:00
Linus Torvalds
798bb342e0 Rust changes for v6.13
Toolchain and infrastructure:
 
  - Enable a series of lints, including safety-related ones, e.g. the
    compiler will now warn about missing safety comments, as well as
    unnecessary ones. How safety documentation is organized is a frequent
    source of review comments, thus having the compiler guide new
    developers on where they are expected (and where not) is very nice.
 
  - Start using '#[expect]': an interesting feature in Rust (stabilized
    in 1.81.0) that makes the compiler warn if an expected warning was
    _not_ emitted. This is useful to avoid forgetting cleaning up locally
    ignored diagnostics ('#[allow]'s).
 
  - Introduce '.clippy.toml' configuration file for Clippy, the Rust
    linter, which will allow us to tweak its behaviour. For instance, our
    first use cases are declaring a disallowed macro and, more
    importantly, enabling the checking of private items.
 
  - Lints-related fixes and cleanups related to the items above.
 
  - Migrate from 'receiver_trait' to 'arbitrary_self_types': to get the
    kernel into stable Rust, one of the major pieces of the puzzle is the
    support to write custom types that can be used as 'self', i.e. as
    receivers, since the kernel needs to write types such as 'Arc' that
    common userspace Rust would not. 'arbitrary_self_types' has been
    accepted to become stable, and this is one of the steps required to
    get there.
 
  - Remove usage of the 'new_uninit' unstable feature.
 
  - Use custom C FFI types. Includes a new 'ffi' crate to contain our
    custom mapping, instead of using the standard library 'core::ffi'
    one. The actual remapping will be introduced in a later cycle.
 
  - Map '__kernel_{size_t,ssize_t,ptrdiff_t}' to 'usize'/'isize' instead
    of 32/64-bit integers.
 
  - Fix 'size_t' in bindgen generated prototypes of C builtins.
 
  - Warn on bindgen < 0.69.5 and libclang >= 19.1 due to a double issue
    in the projects, which we managed to trigger with the upcoming
    tracepoint support. It includes a build test since some distributions
    backported the fix (e.g. Debian -- thanks!). All major distributions
    we list should be now OK except Ubuntu non-LTS.
 
 'macros' crate:
 
  - Adapt the build system to be able run the doctests there too; and
    clean up and enable the corresponding doctests.
 
 'kernel' crate:
 
  - Add 'alloc' module with generic kernel allocator support and remove
    the dependency on the Rust standard library 'alloc' and the extension
    traits we used to provide fallible methods with flags.
 
    Add the 'Allocator' trait and its implementations '{K,V,KV}malloc'.
    Add the 'Box' type (a heap allocation for a single value of type 'T'
    that is also generic over an allocator and considers the kernel's GFP
    flags) and its shorthand aliases '{K,V,KV}Box'. Add 'ArrayLayout'
    type. Add 'Vec' (a contiguous growable array type) and its shorthand
    aliases '{K,V,KV}Vec', including iterator support.
 
    For instance, now we may write code such as:
 
        let mut v = KVec::new();
        v.push(1, GFP_KERNEL)?;
        assert_eq!(&v, &[1]);
 
    Treewide, move as well old users to these new types.
 
  - 'sync' module: add global lock support, including the
    'GlobalLockBackend' trait; the 'Global{Lock,Guard,LockedBy}' types
     and the 'global_lock!' macro. Add the 'Lock::try_lock' method.
 
  - 'error' module: optimize 'Error' type to use 'NonZeroI32' and make
    conversion functions public.
 
  - 'page' module: add 'page_align' function.
 
  - Add 'transmute' module with the existing 'FromBytes' and 'AsBytes'
    traits.
 
  - 'block::mq::request' module: improve rendered documentation.
 
  - 'types' module: extend 'Opaque' type documentation and add simple
    examples for the 'Either' types.
 
 drm/panic:
 
  - Clean up a series of Clippy warnings.
 
 Documentation:
 
  - Add coding guidelines for lints and the '#[expect]' feature.
 
  - Add Ubuntu to the list of distributions in the Quick Start guide.
 
 MAINTAINERS:
  - Add Danilo Krummrich as maintainer of the new 'alloc' module.
 
 And a few other small cleanups and fixes.
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Merge tag 'rust-6.13' of https://github.com/Rust-for-Linux/linux

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

   - Enable a series of lints, including safety-related ones, e.g. the
     compiler will now warn about missing safety comments, as well as
     unnecessary ones. How safety documentation is organized is a
     frequent source of review comments, thus having the compiler guide
     new developers on where they are expected (and where not) is very
     nice.

   - Start using '#[expect]': an interesting feature in Rust (stabilized
     in 1.81.0) that makes the compiler warn if an expected warning was
     _not_ emitted. This is useful to avoid forgetting cleaning up
     locally ignored diagnostics ('#[allow]'s).

   - Introduce '.clippy.toml' configuration file for Clippy, the Rust
     linter, which will allow us to tweak its behaviour. For instance,
     our first use cases are declaring a disallowed macro and, more
     importantly, enabling the checking of private items.

   - Lints-related fixes and cleanups related to the items above.

   - Migrate from 'receiver_trait' to 'arbitrary_self_types': to get the
     kernel into stable Rust, one of the major pieces of the puzzle is
     the support to write custom types that can be used as 'self', i.e.
     as receivers, since the kernel needs to write types such as 'Arc'
     that common userspace Rust would not. 'arbitrary_self_types' has
     been accepted to become stable, and this is one of the steps
     required to get there.

   - Remove usage of the 'new_uninit' unstable feature.

   - Use custom C FFI types. Includes a new 'ffi' crate to contain our
     custom mapping, instead of using the standard library 'core::ffi'
     one. The actual remapping will be introduced in a later cycle.

   - Map '__kernel_{size_t,ssize_t,ptrdiff_t}' to 'usize'/'isize'
     instead of 32/64-bit integers.

   - Fix 'size_t' in bindgen generated prototypes of C builtins.

   - Warn on bindgen < 0.69.5 and libclang >= 19.1 due to a double issue
     in the projects, which we managed to trigger with the upcoming
     tracepoint support. It includes a build test since some
     distributions backported the fix (e.g. Debian -- thanks!). All
     major distributions we list should be now OK except Ubuntu non-LTS.

  'macros' crate:

   - Adapt the build system to be able run the doctests there too; and
     clean up and enable the corresponding doctests.

  'kernel' crate:

   - Add 'alloc' module with generic kernel allocator support and remove
     the dependency on the Rust standard library 'alloc' and the
     extension traits we used to provide fallible methods with flags.

     Add the 'Allocator' trait and its implementations '{K,V,KV}malloc'.
     Add the 'Box' type (a heap allocation for a single value of type
     'T' that is also generic over an allocator and considers the
     kernel's GFP flags) and its shorthand aliases '{K,V,KV}Box'. Add
     'ArrayLayout' type. Add 'Vec' (a contiguous growable array type)
     and its shorthand aliases '{K,V,KV}Vec', including iterator
     support.

     For instance, now we may write code such as:

         let mut v = KVec::new();
         v.push(1, GFP_KERNEL)?;
         assert_eq!(&v, &[1]);

     Treewide, move as well old users to these new types.

   - 'sync' module: add global lock support, including the
     'GlobalLockBackend' trait; the 'Global{Lock,Guard,LockedBy}' types
     and the 'global_lock!' macro. Add the 'Lock::try_lock' method.

   - 'error' module: optimize 'Error' type to use 'NonZeroI32' and make
     conversion functions public.

   - 'page' module: add 'page_align' function.

   - Add 'transmute' module with the existing 'FromBytes' and 'AsBytes'
     traits.

   - 'block::mq::request' module: improve rendered documentation.

   - 'types' module: extend 'Opaque' type documentation and add simple
     examples for the 'Either' types.

  drm/panic:

   - Clean up a series of Clippy warnings.

  Documentation:

   - Add coding guidelines for lints and the '#[expect]' feature.

   - Add Ubuntu to the list of distributions in the Quick Start guide.

  MAINTAINERS:

   - Add Danilo Krummrich as maintainer of the new 'alloc' module.

  And a few other small cleanups and fixes"

* tag 'rust-6.13' of https://github.com/Rust-for-Linux/linux: (82 commits)
  rust: alloc: Fix `ArrayLayout` allocations
  docs: rust: remove spurious item in `expect` list
  rust: allow `clippy::needless_lifetimes`
  rust: warn on bindgen < 0.69.5 and libclang >= 19.1
  rust: use custom FFI integer types
  rust: map `__kernel_size_t` and friends also to usize/isize
  rust: fix size_t in bindgen prototypes of C builtins
  rust: sync: add global lock support
  rust: macros: enable the rest of the tests
  rust: macros: enable paste! use from macro_rules!
  rust: enable macros::module! tests
  rust: kbuild: expand rusttest target for macros
  rust: types: extend `Opaque` documentation
  rust: block: fix formatting of `kernel::block::mq::request` module
  rust: macros: fix documentation of the paste! macro
  rust: kernel: fix THIS_MODULE header path in ThisModule doc comment
  rust: page: add Rust version of PAGE_ALIGN
  rust: helpers: remove unnecessary header includes
  rust: exports: improve grammar in commentary
  drm/panic: allow verbose version check
  ...
2024-11-26 14:00:26 -08:00
Gary Guo
d072acda48 rust: use custom FFI integer types
Currently FFI integer types are defined in libcore. This commit creates
the `ffi` crate and asks bindgen to use that crate for FFI integer types
instead of `core::ffi`.

This commit is preparatory and no type changes are made in this commit
yet.

Signed-off-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20240913213041.395655-4-gary@garyguo.net
[ Added `rustdoc`, `rusttest` and KUnit tests support. Rebased on top of
  `rust-next` (e.g. migrated more `core::ffi` cases). Reworded crate
  docs slightly and formatted. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-11-10 23:58:00 +01:00
Alice Ryhl
8eea62ff94 rust: sync: add global lock support
Add support for creating global variables that are wrapped in a mutex or
spinlock.

The implementation here is intended to replace the global mutex
workaround found in the Rust Binder RFC [1]. In both cases, the global
lock must be initialized before first use. The macro is unsafe to use
for the same reason.

The separate initialization step is required because it is tricky to
access the value of __ARCH_SPIN_LOCK_UNLOCKED from Rust. Doing so will
require changes to the C side. That change will happen as a follow-up to
this patch.

Link: https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-2-08ba9197f637@google.com/#Z31drivers:android:context.rs [1]
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20241023-static-mutex-v6-1-d7efdadcc84f@google.com
[ Simplified a few intra-doc links. Formatted a few comments. Reworded
  title. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-11-10 22:56:57 +01:00
Danilo Krummrich
58eff8e872 rust: treewide: switch to the kernel Vec type
Now that we got the kernel `Vec` in place, convert all existing `Vec`
users to make use of it.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20241004154149.93856-20-dakr@kernel.org
[ Converted `kasan_test_rust.rs` too, as discussed. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-10-15 23:10:32 +02:00
Danilo Krummrich
8373147ce4 rust: treewide: switch to our kernel Box type
Now that we got the kernel `Box` type in place, convert all existing
`Box` users to make use of it.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20241004154149.93856-13-dakr@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-10-15 22:56:59 +02:00
Filipe Xavier
f4c2c90bb7 rust: lock: add trylock method support for lock backend
Add a non-blocking trylock method to lock backend interface, mutex and
spinlock implementations. It includes a C helper for spin_trylock.

Rust Binder will use this method together with the new shrinker
abstractions to avoid deadlocks in the memory shrinker.

Link: https://lore.kernel.org/all/20240912-shrinker-v1-1-18b7f1253553@google.com
Signed-off-by: Filipe Xavier <felipe_life@live.com>
Reviewed-by: Fiona Behrens <me@kloenk.dev>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/BL0PR02MB4914579914884B5D7473B3D6E96A2@BL0PR02MB4914.namprd02.prod.outlook.com
[ Slightly reworded. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-10-10 00:33:42 +02:00
Christian Brauner
70d7f7dbd9
Merge patch series "File abstractions needed by Rust Binder"
Alice Ryhl <aliceryhl@google.com> says:

This patchset contains the file abstractions needed by the Rust
implementation of the Binder driver.

Please see the Rust Binder RFC for usage examples:
https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-0-08ba9197f637@google.com

Users of "rust: types: add `NotThreadSafe`":
	[PATCH 5/9] rust: file: add `FileDescriptorReservation`

Users of "rust: task: add `Task::current_raw`":
	[PATCH 7/9] rust: file: add `Kuid` wrapper
	[PATCH 8/9] rust: file: add `DeferredFdCloser`

Users of "rust: file: add Rust abstraction for `struct file`":
	[PATCH RFC 02/20] rust_binder: add binderfs support to Rust binder
	[PATCH RFC 03/20] rust_binder: add threading support

Users of "rust: cred: add Rust abstraction for `struct cred`":
	[PATCH RFC 05/20] rust_binder: add nodes and context managers
	[PATCH RFC 06/20] rust_binder: add oneway transactions
	[PATCH RFC 11/20] rust_binder: send nodes in transaction
	[PATCH RFC 13/20] rust_binder: add BINDER_TYPE_FD support

Users of "rust: security: add abstraction for secctx":
	[PATCH RFC 06/20] rust_binder: add oneway transactions

Users of "rust: file: add `FileDescriptorReservation`":
	[PATCH RFC 13/20] rust_binder: add BINDER_TYPE_FD support
	[PATCH RFC 14/20] rust_binder: add BINDER_TYPE_FDA support

Users of "rust: file: add `Kuid` wrapper":
	[PATCH RFC 05/20] rust_binder: add nodes and context managers
	[PATCH RFC 06/20] rust_binder: add oneway transactions

Users of "rust: file: add abstraction for `poll_table`":
	[PATCH RFC 07/20] rust_binder: add epoll support

This patchset has some uses of read_volatile in place of READ_ONCE.
Please see the following rfc for context on this:
https://lore.kernel.org/all/20231025195339.1431894-1-boqun.feng@gmail.com/

* patches from https://lore.kernel.org/r/20240915-alice-file-v10-0-88484f7a3dcf@google.com:
  rust: file: add abstraction for `poll_table`
  rust: file: add `Kuid` wrapper
  rust: file: add `FileDescriptorReservation`
  rust: security: add abstraction for secctx
  rust: cred: add Rust abstraction for `struct cred`
  rust: file: add Rust abstraction for `struct file`
  rust: task: add `Task::current_raw`
  rust: types: add `NotThreadSafe`

Link: https://lore.kernel.org/r/20240915-alice-file-v10-0-88484f7a3dcf@google.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-08 14:32:22 +02:00
Gary Guo
c95bbb59a9 rust: enable arbitrary_self_types and remove Receiver
The term "receiver" means that a type can be used as the type of `self`,
and thus enables method call syntax `foo.bar()` instead of
`Foo::bar(foo)`. Stable Rust as of today (1.81) enables a limited
selection of types (primitives and types in std, e.g. `Box` and `Arc`)
to be used as receivers, while custom types cannot.

We want the kernel `Arc` type to have the same functionality as the Rust
std `Arc`, so we use the `Receiver` trait (gated behind `receiver_trait`
unstable feature) to gain the functionality.

The `arbitrary_self_types` RFC [1] (tracking issue [2]) is accepted and
it will allow all types that implement a new `Receiver` trait (different
from today's unstable trait) to be used as receivers. This trait will be
automatically implemented for all `Deref` types, which include our `Arc`
type, so we no longer have to opt-in to be used as receiver. To prepare
us for the change, remove the `Receiver` implementation and the
associated feature. To still allow `Arc` and others to be used as method
receivers, turn on `arbitrary_self_types` feature instead.

This feature gate is introduced in 1.23.0. It used to enable both
`Deref` types and raw pointer types to be used as receivers, but the
latter is now split into a different feature gate in Rust 1.83 nightly.
We do not need receivers on raw pointers so this change would not affect
us and usage of `arbitrary_self_types` feature would work for all Rust
versions that we support (>=1.78).

Cc: Adrian Taylor <ade@hohum.me.uk>
Link: https://github.com/rust-lang/rfcs/pull/3519 [1]
Link: https://github.com/rust-lang/rust/issues/44874 [2]
Signed-off-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240915132734.1653004-1-gary@garyguo.net
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-10-07 21:39:57 +02:00
Miguel Ojeda
2f390cc589 rust: provide proper code documentation titles
Rust 1.82.0's Clippy is introducing [1][2] a new warn-by-default lint,
`too_long_first_doc_paragraph` [3], which is intended to catch titles
of code documentation items that are too long (likely because no title
was provided and the item documentation starts with a paragraph).

This lint does not currently trigger anywhere, but it does detect a couple
cases if checking for private items gets enabled (which we will do in
the next commit):

    error: first doc comment paragraph is too long
      --> rust/kernel/init/__internal.rs:18:1
       |
    18 | / /// This is the module-internal type implementing `PinInit` and `Init`. It is unsafe to create this
    19 | | /// type, since the closure needs to fulfill the same safety requirement as the
    20 | | /// `__pinned_init`/`__init` functions.
       | |_
       |
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#too_long_first_doc_paragraph
       = note: `-D clippy::too-long-first-doc-paragraph` implied by `-D warnings`
       = help: to override `-D warnings` add `#[allow(clippy::too_long_first_doc_paragraph)]`

    error: first doc comment paragraph is too long
     --> rust/kernel/sync/arc/std_vendor.rs:3:1
      |
    3 | / //! The contents of this file come from the Rust standard library, hosted in
    4 | | //! the <https://github.com/rust-lang/rust> repository, licensed under
    5 | | //! "Apache-2.0 OR MIT" and adapted for kernel use. For copyright details,
    6 | | //! see <https://github.com/rust-lang/rust/blob/master/COPYRIGHT>.
      | |_
      |
      = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#too_long_first_doc_paragraph

Thus clean those two instances.

In addition, since we have a second `std_vendor.rs` file with a similar
header, do the same there too (even if that one does not trigger the lint,
because it is `doc(hidden)`).

Link: https://github.com/rust-lang/rust/pull/129531 [1]
Link: https://github.com/rust-lang/rust-clippy/pull/12993 [2]
Link: https://rust-lang.github.io/rust-clippy/master/index.html#/too_long_first_doc_paragraph [3]
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Tested-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20240904204347.168520-15-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-10-07 21:39:57 +02:00
Miguel Ojeda
5e7c9b84ad rust: sync: remove unneeded #[allow(clippy::non_send_fields_in_send_ty)]
Rust 1.58.0 (before Rust was merged into the kernel) made Clippy's
`non_send_fields_in_send_ty` lint part of the `suspicious` lint group for
a brief window of time [1] until the minor version 1.58.1 got released
a week after, where the lint was moved back to `nursery`.

By that time, we had already upgraded to that Rust version, and thus we
had `allow`ed the lint here for `CondVar`.

Nowadays, Clippy's `non_send_fields_in_send_ty` would still trigger here
if it were enabled.

Moreover, if enabled, `Lock<T, B>` and `Task` would also require an
`allow`. Therefore, it does not seem like someone is actually enabling it
(in, e.g., a custom flags build).

Finally, the lint does not appear to have had major improvements since
then [2].

Thus remove the `allow` since it is unneeded.

Link: https://github.com/rust-lang/rust/blob/master/RELEASES.md#version-1581-2022-01-20 [1]
Link: https://github.com/rust-lang/rust-clippy/issues/8045 [2]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Tested-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20240904204347.168520-11-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-10-07 21:39:05 +02:00
Miguel Ojeda
c28bfe76e4 rust: enable clippy::unnecessary_safety_comment lint
In Rust 1.67.0, Clippy added the `unnecessary_safety_comment` lint [1],
which is the "inverse" of `undocumented_unsafe_blocks`: it finds places
where safe code has a `// SAFETY` comment attached.

The lint currently finds 3 places where we had such mistakes, thus it
seems already quite useful.

Thus clean those and enable it.

Link: https://rust-lang.github.io/rust-clippy/master/index.html#/unnecessary_safety_comment [1]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Tested-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20240904204347.168520-6-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-10-07 21:39:05 +02:00
Miguel Ojeda
db4f72c904 rust: enable clippy::undocumented_unsafe_blocks lint
Checking that we are not missing any `// SAFETY` comments in our `unsafe`
blocks is something we have wanted to do for a long time, as well as
cleaning up the remaining cases that were not documented [1].

Back when Rust for Linux started, this was something that could have
been done via a script, like Rust's `tidy`. Soon after, in Rust 1.58.0,
Clippy implemented the `undocumented_unsafe_blocks` lint [2].

Even though the lint has a few false positives, e.g. in some cases where
attributes appear between the comment and the `unsafe` block [3], there
are workarounds and the lint seems quite usable already.

Thus enable the lint now.

We still have a few cases to clean up, so just allow those for the moment
by writing a `TODO` comment -- some of those may be good candidates for
new contributors.

Link: https://github.com/Rust-for-Linux/linux/issues/351 [1]
Link: https://rust-lang.github.io/rust-clippy/master/#/undocumented_unsafe_blocks [2]
Link: https://github.com/rust-lang/rust-clippy/issues/13189 [3]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Tested-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20240904204347.168520-5-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-10-07 21:39:05 +02:00
Alice Ryhl
ac681835b6
rust: file: add abstraction for poll_table
The existing `CondVar` abstraction is a wrapper around
`wait_queue_head`, but it does not support all use-cases of the C
`wait_queue_head` type. To be specific, a `CondVar` cannot be registered
with a `struct poll_table`. This limitation has the advantage that you
do not need to call `synchronize_rcu` when destroying a `CondVar`.

However, we need the ability to register a `poll_table` with a
`wait_queue_head` in Rust Binder. To enable this, introduce a type
called `PollCondVar`, which is like `CondVar` except that you can
register a `poll_table`. We also introduce `PollTable`, which is a safe
wrapper around `poll_table` that is intended to be used with
`PollCondVar`.

The destructor of `PollCondVar` unconditionally calls `synchronize_rcu`
to ensure that the removal of epoll waiters has fully completed before
the `wait_queue_head` is destroyed.

That said, `synchronize_rcu` is rather expensive and is not needed in
all cases: If we have never registered a `poll_table` with the
`wait_queue_head`, then we don't need to call `synchronize_rcu`. (And
this is a common case in Binder - not all processes use Binder with
epoll.) The current implementation does not account for this, but if we
find that it is necessary to improve this, a future patch could store a
boolean next to the `wait_queue_head` to keep track of whether a
`poll_table` has ever been registered.

Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240915-alice-file-v10-8-88484f7a3dcf@google.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-09-30 13:02:29 +02:00
Alice Ryhl
e7572e5dea
rust: types: add NotThreadSafe
This introduces a new marker type for types that shouldn't be thread
safe. By adding a field of this type to a struct, it becomes non-Send
and non-Sync, which means that it cannot be accessed in any way from
threads other than the one it was created on.

This is useful for APIs that require globals such as `current` to remain
constant while the value exists.

We update two existing users in the Kernel to use this helper:

 * `Task::current()` - moving the return type of this value to a
   different thread would not be safe as you can no longer be guaranteed
   that the `current` pointer remains valid.
 * Lock guards. Mutexes and spinlocks should be unlocked on the same
   thread as where they were locked, so we enforce this using the Send
   trait.

There are also additional users in later patches of this patchset. See
[1] and [2] for the discussion that led to the introduction of this
patch.

Link: https://lore.kernel.org/all/nFDPJFnzE9Q5cqY7FwSMByRH2OAn_BpI4H53NQfWIlN6I2qfmAqnkp2wRqn0XjMO65OyZY4h6P4K2nAGKJpAOSzksYXaiAK_FoH_8QbgBI4=@proton.me/ [1]
Link: https://lore.kernel.org/all/nFDPJFnzE9Q5cqY7FwSMByRH2OAn_BpI4H53NQfWIlN6I2qfmAqnkp2wRqn0XjMO65OyZY4h6P4K2nAGKJpAOSzksYXaiAK_FoH_8QbgBI4=@proton.me/ [2]
Suggested-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240915-alice-file-v10-1-88484f7a3dcf@google.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-09-30 13:02:27 +02:00
Alice Ryhl
a8ee30f45d rust: sync: require T: Sync for LockedBy::access
The `LockedBy::access` method only requires a shared reference to the
owner, so if we have shared access to the `LockedBy` from several
threads at once, then two threads could call `access` in parallel and
both obtain a shared reference to the inner value. Thus, require that
`T: Sync` when calling the `access` method.

An alternative is to require `T: Sync` in the `impl Sync for LockedBy`.
This patch does not choose that approach as it gives up the ability to
use `LockedBy` with `!Sync` types, which is okay as long as you only use
`access_mut`.

Cc: stable@vger.kernel.org
Fixes: 7b1f55e3a9 ("rust: sync: introduce `LockedBy`")
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20240915-locked-by-sync-fix-v2-1-1a8d89710392@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-09-26 17:51:49 +02:00