Now that we removed `VecExt` and the corresponding includes in
prelude.rs, add the new kernel `Vec` type instead.
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/20241004154149.93856-22-dakr@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Now that all existing `Vec` users were moved to the kernel `Vec` type,
remove the `VecExt` extension.
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/20241004154149.93856-21-dakr@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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>
Currently, we can't implement `FromIterator`. There are a couple of
issues with this trait in the kernel, namely:
- Rust's specialization feature is unstable. This prevents us to
optimize for the special case where `I::IntoIter` equals `Vec`'s
`IntoIter` type.
- We also can't use `I::IntoIter`'s type ID either to work around this,
since `FromIterator` doesn't require this type to be `'static`.
- `FromIterator::from_iter` does return `Self` instead of
`Result<Self, AllocError>`, hence we can't properly handle allocation
failures.
- Neither `Iterator::collect` nor `FromIterator::from_iter` can handle
additional allocation flags.
Instead, provide `IntoIter::collect`, such that we can at least convert
`IntoIter` into a `Vec` again.
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20241004154149.93856-19-dakr@kernel.org
[ Added newline in documentation, changed case of section to be
consistent with an existing one, fixed typo. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Implement `IntoIterator` for `Vec`, `Vec`'s `IntoIter` type, as well as
`Iterator` for `IntoIter`.
`Vec::into_iter` disassembles the `Vec` into its raw parts; additionally,
`IntoIter` keeps track of a separate pointer, which is incremented
correspondingly as the iterator advances, while the length, or the count
of elements, is decremented.
This also means that `IntoIter` takes the ownership of the backing
buffer and is responsible to drop the remaining elements and free the
backing buffer, if it's dropped.
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/20241004154149.93856-18-dakr@kernel.org
[ Fixed typos. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
`Vec` provides a contiguous growable array type with contents allocated
with the kernel's allocators (e.g. `Kmalloc`, `Vmalloc` or `KVmalloc`).
In contrast to Rust's stdlib `Vec` type, the kernel `Vec` type considers
the kernel's GFP flags for all appropriate functions, always reports
allocation failures through `Result<_, AllocError>` and remains
independent from unstable features.
[ This patch starts using a new unstable feature, `inline_const`, but
it was stabilized in Rust 1.79.0, i.e. the next version after the
minimum one, thus it will not be an issue. - Miguel ]
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/20241004154149.93856-17-dakr@kernel.org
[ Cleaned `rustdoc` unescaped backtick warning, added a couple more
backticks elsewhere, fixed typos, sorted `feature`s, rewrapped
documentation lines. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
When allocating memory for arrays using allocators, the `Layout::array`
function is typically used. It returns a result, since the given size
might be too big. However, `Vec` and its iterators store their allocated
capacity and thus they already did check that the size is not too big.
The `ArrayLayout` type provides this exact behavior, as it can be
infallibly converted into a `Layout`. Instead of a `usize` capacity,
`Vec` and other similar array-storing types can use `ArrayLayout`
instead.
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20241004154149.93856-16-dakr@kernel.org
[ Formatted a few comments. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Now that we removed `BoxExt` and the corresponding includes in
prelude.rs, add the new kernel `Box` type instead.
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/20241004154149.93856-15-dakr@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Now that all existing `Box` users were moved to the kernel `Box` type,
remove the `BoxExt` extension and all other related extensions.
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/20241004154149.93856-14-dakr@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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>
`Box` provides the simplest way to allocate memory for a generic type
with one of the kernel's allocators, e.g. `Kmalloc`, `Vmalloc` or
`KVmalloc`.
In contrast to Rust's `Box` type, the kernel `Box` type considers the
kernel's GFP flags for all appropriate functions, always reports
allocation failures through `Result<_, AllocError>` and remains
independent from unstable features.
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/20241004154149.93856-12-dakr@kernel.org
[ Added backticks, fixed typos. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Some test cases in subsequent patches provoke allocation failures. Add
`__GFP_NOWARN` to enable test cases to silence unpleasant warnings.
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/20241004154149.93856-11-dakr@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Implement `Allocator` for `KVmalloc`, an `Allocator` that tries to
allocate memory with `kmalloc` first and, on failure, falls back to
`vmalloc`.
All memory allocations made with `KVmalloc` end up in
`kvrealloc_noprof()`; all frees in `kvfree()`.
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/20241004154149.93856-10-dakr@kernel.org
[ Reworded typo. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Implement `Allocator` for `Vmalloc`, the kernel's virtually contiguous
allocator, typically used for larger objects, (much) larger than page
size.
All memory allocations made with `Vmalloc` end up in `vrealloc()`.
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/20241004154149.93856-9-dakr@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
`Allocator`s, such as `Kmalloc`, will be used by e.g. `Box` and `Vec` in
subsequent patches, and hence this dependency propagates throughout the
whole kernel.
Add the `allocator_test` module that provides an empty implementation
for all `Allocator`s in the kernel, such that we don't break the
`rusttest` make target in subsequent patches.
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/20241004154149.93856-8-dakr@kernel.org
[ Added missing `_old_layout` parameter as discussed. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Implement `Allocator` for `Kmalloc`, the kernel's default allocator,
typically used for objects smaller than page size.
All memory allocations made with `Kmalloc` end up in `krealloc()`.
It serves as allocator for the subsequently introduced types `KBox` and
`KVec`.
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/20241004154149.93856-7-dakr@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Subsequent patches implement allocators such as `Kmalloc`, `Vmalloc`,
`KVmalloc`; we need them to be available outside of the kernel crate as
well.
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/20241004154149.93856-6-dakr@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
`ReallocFunc` is an abstraction for the kernel's realloc derivates, such
as `krealloc`, `vrealloc` and `kvrealloc`.
All of the named functions share the same function signature and
implement the same semantics. The `ReallocFunc` abstractions provides a
generalized wrapper around those, to trivialize the implementation of
`Kmalloc`, `Vmalloc` and `KVmalloc` in subsequent patches.
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/20241004154149.93856-5-dakr@kernel.org
[ Added temporary `allow(dead_code)` for `dangling_from_layout` to clean
warning in `rusttest` target as discussed in the list (but it is
needed earlier, i.e. in this patch already). Added colon. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
When building miscdevice with clippy warnings, the following warning is
emitted:
warning: casting to the same type is unnecessary (`u32` -> `u32`)
--> /home/aliceryhl/rust-for-linux/rust/kernel/miscdevice.rs:220:28
|
220 | match T::ioctl(device, cmd as u32, arg as usize) {
| ^^^^^^^^^^ help: try: `cmd`
|
= help: for further information visit
https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_cast
= note: `-W clippy::unnecessary-cast` implied by `-W clippy::all`
= help: to override `-W clippy::all` add `#[allow(clippy::unnecessary_cast)]`
Thus, fix it.
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20241015-miscdevice-cint-cast-v1-1-fcf4b75700ac@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The `Task` struct has several safety comments that aren't so great. For
example, the reason that it's okay to read the `pid` is that the field
is immutable, so there is no data race, which is not what the safety
comment says.
Thus, improve the safety comments. Also add an `as_ptr` helper. This
makes it easier to read the various accessors on Task, as `self.0` may
be confusing syntax for new Rust users.
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20241015-task-safety-cmnts-v1-1-46ee92c82768@google.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Separate `aligned_size` from `krealloc_aligned`.
Subsequent patches implement `Allocator` derivates, such as `Kmalloc`,
that require `aligned_size` and replace the original `krealloc_aligned`.
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/20241004154149.93856-3-dakr@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Add a kernel specific `Allocator` trait, that in contrast to the one in
Rust's core library doesn't require unstable features and supports GFP
flags.
Subsequent patches add the following trait implementors: `Kmalloc`,
`Vmalloc` and `KVmalloc`.
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/20241004154149.93856-2-dakr@kernel.org
[ Fixed typo. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Here is a single driver core fix, and a .mailmap update, for 6.12-rc3.
The fix is for the rust driver core bindings, turned out that the
from_raw binding wasn't a good idea (don't want to pass a pointer to a
reference counted object without actually incrementing the pointer.) So
this change fixes it up as the from_raw binding came in in -rc1.
The other change is a .mailmap update.
Both have been in linux-next for a while with no reported issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-6.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core fixes from Greg KH:
"Here is a single driver core fix, and a .mailmap update.
The fix is for the rust driver core bindings, turned out that the
from_raw binding wasn't a good idea (don't want to pass a pointer to a
reference counted object without actually incrementing the pointer.)
So this change fixes it up as the from_raw binding came in in -rc1.
The other change is a .mailmap update.
Both have been in linux-next for a while with no reported issues"
* tag 'driver-core-6.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
mailmap: update mail for Fiona Behrens
rust: device: change the from_raw() function
Refactor the `FromBytes` and `AsBytes` traits from `types.rs` into a new
`transmute.rs` module:
- Add `rust/kernel/transmute.rs` with the definitions of `FromBytes`
and `AsBytes`.
- Remove the same trait definitions from `rust/kernel/types.rs`.
- Update `rust/kernel/uaccess.rs` to import `AsBytes` and `FromBytes`
from `transmute.rs`.
The traits and their implementations remain unchanged.
Suggested-by: Benno Lossin <benno.lossin@proton.me>
Link: https://github.com/Rust-for-Linux/linux/issues/1117
Signed-off-by: Aliet Exposito Garcia <aliet.exposito@gmail.com>
Reviewed-by: Fiona Behrens <me@kloenk.dev>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20240918225115.2309224-2-aliet.exposito@gmail.com
[ Rebased on top of the lints series and slightly reworded. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Optimize `Result<(), Error>` size by changing `Error` type to
`NonZero*` for niche optimization.
This reduces the space used by the `Result` type, as the `NonZero*`
type enables the compiler to apply more efficient memory layout.
For example, the `Result<(), Error>` changes size from 8 to 4 bytes.
Link: https://github.com/Rust-for-Linux/linux/issues/1120
Signed-off-by: Filipe Xavier <felipe_life@live.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Fiona Behrens <me@kloenk.dev>
Link: https://lore.kernel.org/r/BL0PR02MB4914B9B088865CF237731207E9732@BL0PR02MB4914.namprd02.prod.outlook.com
[ Removed unneeded block around `match`, added backticks in panic
message and added intra-doc link. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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>
`dbg!` contains adapted code from Rust upstream. Compare the kernel
code with the Rust upstream one and update missing column numbers in
`dbg!` outputs.
Column numbers are not copied but adjusted for the kernel's examples.
Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://github.com/Rust-for-Linux/linux/issues/1124
Signed-off-by: Deepak Thukral <iapain@gmail.com>
Link: https://lore.kernel.org/r/20241004125616.49886-1-iapain@gmail.com
[ Fixed typo and slightly reworded. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Provide a `MiscDevice` trait that lets you specify the file operations
that you wish to provide for your misc device. For now, only three file
operations are provided: open, close, ioctl.
These abstractions only support MISC_DYNAMIC_MINOR. This enforces that
new miscdevices should not hard-code a minor number.
When implementing ioctl, the Result type is used. This means that you
can choose to return either of:
* An integer of type isize.
* An errno using the kernel::error::Error type.
When returning an isize, the integer is returned verbatim. It's mainly
intended for returning positive integers to userspace. However, it is
technically possible to return errors via the isize return value too.
To avoid having a dependency on files, this patch does not provide the
file operations callbacks a pointer to the file. This means that they
cannot check file properties such as O_NONBLOCK (which Binder needs).
Support for that can be added as a follow-up.
To avoid having a dependency on vma, this patch does not provide any way
to implement mmap (which Binder needs). Support for that can be added as
a follow-up.
Rust Binder will use these abstractions to create the /dev/binder file
when binderfs is disabled.
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/rust-for-linux/20240328195457.225001-1-wedsonaf@gmail.com/
Link: https://lore.kernel.org/r/20241001-b4-miscdevice-v2-2-330d760041fa@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This will be used by the miscdevice abstractions, as the C function
`misc_register` is fallible.
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Fiona Behrens <me@kloenk.dev>
Link: https://lore.kernel.org/r/20241001-b4-miscdevice-v2-1-330d760041fa@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The lifetime of `PidNamespace` is bound to `Task` and `struct pid`.
The `PidNamespace` of a `Task` doesn't ever change once the `Task` is
alive. A `unshare(CLONE_NEWPID)` or `setns(fd_pidns/pidfd, CLONE_NEWPID)`
will not have an effect on the calling `Task`'s pid namespace. It will
only effect the pid namespace of children created by the calling `Task`.
This invariant guarantees that after having acquired a reference to a
`Task`'s pid namespace it will remain unchanged.
When a task has exited and been reaped `release_task()` will be called.
This will set the `PidNamespace` of the task to `NULL`. So retrieving
the `PidNamespace` of a task that is dead will return `NULL`. Note, that
neither holding the RCU lock nor holding a referencing count to the
`Task` will prevent `release_task()` being called.
In order to retrieve the `PidNamespace` of a `Task` the
`task_active_pid_ns()` function can be used. There are two cases to
consider:
(1) retrieving the `PidNamespace` of the `current` task (2) retrieving
the `PidNamespace` of a non-`current` task
From system call context retrieving the `PidNamespace` for case (1) is
always safe and requires neither RCU locking nor a reference count to be
held. Retrieving the `PidNamespace` after `release_task()` for current
will return `NULL` but no codepath like that is exposed to Rust.
Retrieving the `PidNamespace` from system call context for (2) requires
RCU protection. Accessing `PidNamespace` outside of RCU protection
requires a reference count that must've been acquired while holding the
RCU lock. Note that accessing a non-`current` task means `NULL` can be
returned as the non-`current` task could have already passed through
`release_task()`.
To retrieve (1) the `current_pid_ns!()` macro should be used which
ensure that the returned `PidNamespace` cannot outlive the calling
scope. The associated `current_pid_ns()` function should not be called
directly as it could be abused to created an unbounded lifetime for
`PidNamespace`. The `current_pid_ns!()` macro allows Rust to handle the
common case of accessing `current`'s `PidNamespace` without RCU
protection and without having to acquire a reference count.
For (2) the `task_get_pid_ns()` method must be used. This will always
acquire a reference on `PidNamespace` and will return an `Option` to
force the caller to explicitly handle the case where `PidNamespace` is
`None`, something that tends to be forgotten when doing the equivalent
operation in `C`. Missing RCU primitives make it difficult to perform
operations that are otherwise safe without holding a reference count as
long as RCU protection is guaranteed. But it is not important currently.
But we do want it in the future.
Note for (2) the required RCU protection around calling
`task_active_pid_ns()` synchronizes against putting the last reference
of the associated `struct pid` of `task->thread_pid`. The `struct pid`
stored in that field is used to retrieve the `PidNamespace` of the
caller. When `release_task()` is called `task->thread_pid` will be
`NULL`ed and `put_pid()` on said `struct pid` will be delayed in
`free_pid()` via `call_rcu()` allowing everyone with an RCU protected
access to the `struct pid` acquired from `task->thread_pid` to finish.
Link: https://lore.kernel.org/r/20241002-brauner-rust-pid_namespace-v5-1-a90e70d44fde@kernel.org
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This adds a simple seq file abstraction that lets you print to a seq
file using ordinary Rust printing syntax.
An example user from Rust Binder:
pub(crate) fn full_debug_print(
&self,
m: &SeqFile,
owner_inner: &mut ProcessInner,
) -> Result<()> {
let prio = self.node_prio();
let inner = self.inner.access_mut(owner_inner);
seq_print!(
m,
" node {}: u{:016x} c{:016x} pri {}:{} hs {} hw {} cs {} cw {}",
self.debug_id,
self.ptr,
self.cookie,
prio.sched_policy,
prio.prio,
inner.strong.has_count,
inner.weak.has_count,
inner.strong.count,
inner.weak.count,
);
if !inner.refs.is_empty() {
seq_print!(m, " proc");
for node_ref in &inner.refs {
seq_print!(m, " {}", node_ref.process.task.pid());
}
}
seq_print!(m, "\n");
for t in &inner.oneway_todo {
t.debug_print_inner(m, " pending async transaction ");
}
Ok(())
}
The `SeqFile` type is marked not thread safe so that `call_printf` can
be a `&self` method. The alternative is to use `self: Pin<&mut Self>`
which is inconvenient, or to have `SeqFile` wrap a pointer instead of
wrapping the C struct directly.
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20241001-seqfile-v1-1-dfcd0fc21e96@google.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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>
It is cleaner to have a single inner attribute rather than needing
several hidden lines to wrap the macro invocations.
Thus simplify them.
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
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/20240904204347.168520-20-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
In Rust, it is possible to `allow` particular warnings (diagnostics,
lints) locally, making the compiler ignore instances of a given warning
within a given function, module, block, etc.
It is similar to `#pragma GCC diagnostic push` + `ignored` + `pop` in C:
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
static void f(void) {}
#pragma GCC diagnostic pop
But way less verbose:
#[allow(dead_code)]
fn f() {}
By that virtue, it makes it possible to comfortably enable more
diagnostics by default (i.e. outside `W=` levels) that may have some
false positives but that are otherwise quite useful to keep enabled to
catch potential mistakes.
The `#[expect(...)]` attribute [1] takes this further, and makes the
compiler warn if the diagnostic was _not_ produced. For instance, the
following will ensure that, when `f()` is called somewhere, we will have
to remove the attribute:
#[expect(dead_code)]
fn f() {}
If we do not, we get a warning from the compiler:
warning: this lint expectation is unfulfilled
--> x.rs:3:10
|
3 | #[expect(dead_code)]
| ^^^^^^^^^
|
= note: `#[warn(unfulfilled_lint_expectations)]` on by default
This means that `expect`s do not get forgotten when they are not needed.
See the next commit for more details, nuances on its usage and
documentation on the feature.
The attribute requires the `lint_reasons` [2] unstable feature, but it
is becoming stable in 1.81.0 (to be released on 2024-09-05) and it has
already been useful to clean things up in this patch series, finding
cases where the `allow`s should not have been there.
Thus, enable `lint_reasons` and convert some of our `allow`s to `expect`s
where possible.
This feature was also an example of the ongoing collaboration between
Rust and the kernel -- we tested it in the kernel early on and found an
issue that was quickly resolved [3].
Cc: Fridtjof Stoldt <xfrednet@gmail.com>
Cc: Urgau <urgau@numericable.fr>
Link: https://rust-lang.github.io/rfcs/2383-lint-reasons.html#expect-lint-attribute [1]
Link: https://github.com/rust-lang/rust/issues/54503 [2]
Link: https://github.com/rust-lang/rust/issues/114557 [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/20240904204347.168520-18-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
In Rust 1.76.0, Clippy added the `check-private-items` lint configuration
option. When turned on (the default is off), it makes several lints
check private items as well.
In our case, it affects two lints we have enabled [1]:
`missing_safety_doc` and `unnecessary_safety_doc`.
It also seems to affect the new `too_long_first_doc_paragraph` lint [2],
even though the documentation does not mention it.
Thus allow the few instances remaining we currently hit and enable
the lint.
Link: https://doc.rust-lang.org/nightly/clippy/lint_configuration.html#check-private-items [1]
Link: https://rust-lang.github.io/rust-clippy/master/index.html#/too_long_first_doc_paragraph [2]
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/20240904204347.168520-16-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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>
The tag `SAFETY` is used for safety comments, i.e. `// SAFETY`, while a
`Safety` section is used for safety preconditions in code documentation,
i.e. `/// # Safety`.
Fix the three instances recently added in `rbtree` that Clippy would
have normally caught in a public item, so that we can enable checking
of private items in one of the following commits.
Fixes: 98c14e40e0 ("rust: rbtree: add cursor")
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/20240904204347.168520-14-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Back when we used Rust 1.60.0 (before Rust was merged in the kernel),
we added `-Wclippy::dbg_macro` to the compilation flags. This worked
great with our custom `dbg!` macro (vendored from `std`, but slightly
modified to use the kernel printing facilities).
However, in the very next version, 1.61.0, it stopped working [1] since
the lint started to use a Rust diagnostic item rather than a path to find
the `dbg!` macro [1]. This behavior remains until the current nightly
(1.83.0).
Therefore, currently, the `dbg_macro` is not doing anything, which
explains why we can invoke `dbg!` in samples/rust/rust_print.rs`, as well
as why changing the `#[allow()]`s to `#[expect()]`s in `std_vendor.rs`
doctests does not work since they are not fulfilled.
One possible workaround is using `rustc_attrs` like the standard library
does. However, this is intended to be internal, and we just started
supporting several Rust compiler versions, so it is best to avoid it.
Therefore, instead, use `disallowed_macros`. It is a stable lint and
is more flexible (in that we can provide different macros), although
its diagnostic message(s) are not as nice as the specialized one (yet),
and does not allow to set different lint levels per macro/path [2].
In turn, this requires allowing the (intentional) `dbg!` use in the
sample, as one would have expected.
Finally, in a single case, the `allow` is fixed to be an inner attribute,
since otherwise it was not being applied.
Link: https://github.com/rust-lang/rust-clippy/issues/11303 [1]
Link: https://github.com/rust-lang/rust-clippy/issues/11307 [2]
Tested-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20240904204347.168520-13-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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>
These few cases, unlike others in the same file, did not need the `allow`.
Thus clean them up.
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/20240904204347.168520-10-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
In Rust 1.71.0, `rustdoc` added the `unescaped_backticks` lint, which
detects what are typically typos in Markdown formatting regarding inline
code [1], e.g. from the Rust standard library:
/// ... to `deref`/`deref_mut`` must ...
/// ... use [`from_mut`]`. Specifically, ...
It does not seem to have almost any false positives, from the experience
of enabling it in the Rust standard library [2], which will be checked
starting with Rust 1.82.0. The maintainers also confirmed it is ready
to be used.
Thus enable it.
Link: https://doc.rust-lang.org/rustdoc/lints.html#unescaped_backticks [1]
Link: https://github.com/rust-lang/rust/pull/128307 [2]
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/20240904204347.168520-9-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
In Rust 1.73.0, Clippy introduced the `ignored_unit_patterns` lint [1]:
> Matching with `()` explicitly instead of `_` outlines the fact that
> the pattern contains no data. Also it would detect a type change
> that `_` would ignore.
There is only a single case that requires a change:
error: matching over `()` is more explicit
--> rust/kernel/types.rs:176:45
|
176 | ScopeGuard::new_with_data((), move |_| cleanup())
| ^ help: use `()` instead of `_`: `()`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#ignored_unit_patterns
= note: requested on the command line with `-D clippy::ignored-unit-patterns`
Thus clean it up and enable the lint -- no functional change intended.
Link: https://rust-lang.github.io/rust-clippy/master/index.html#/ignored_unit_patterns [1]
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/20240904204347.168520-8-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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>
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>
In order to provide `// SAFETY` comments for every `unsafe impl`, we would
need to repeat them, which is not very useful and would be harder to read.
We could perhaps allow the lint (ideally within a small module), but we
can take the chance to avoid the repetition of the `impl`s themselves
too by using a small local macro, like in other places where we have
had to do this sort of thing.
Thus add the straightforward `impl_{from,as}bytes!` macros and use them
to implement `FromBytes`.
This, in turn, will allow us in the next patch to place a `// SAFETY`
comment that defers to the actual invocation of the macro.
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/20240904204347.168520-4-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Perform the same clean commit b2516f7af9 ("rust: kernel: remove
`#[allow(clippy::new_ret_no_self)]`") did for a case that appeared in
workqueue in parallel in commit 7324b88975 ("rust: workqueue: add
helper for defining work_struct fields"):
Clippy triggered a false positive on its `new_ret_no_self` lint
when using the `pin_init!` macro. Since Rust 1.67.0, that does
not happen anymore, since Clippy learnt to not warn about
`-> impl Trait<Self>` [1][2].
The kernel nowadays uses Rust 1.72.1, thus remove the `#[allow]`.
Link: https://github.com/rust-lang/rust-clippy/issues/7344 [1]
Link: https://github.com/rust-lang/rust-clippy/pull/9733 [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/20240904204347.168520-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
device_table in module_phy_driver macro is defined only when the
driver is built as a module. So a PHY driver imports phy::DeviceId
module in the following way then hits `unused import` warning when
it's compiled as built-in:
use kernel::net::phy::DeviceId;
kernel::module_phy_driver! {
drivers: [PhyQT2025],
device_table: [
DeviceId::new_with_driver::<PhyQT2025>(),
],
Put device_table in a const. It's not included in the kernel image if
unused (when the driver is compiled as built-in), and the compiler
doesn't complain.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://patch.msgid.link/20240930134038.1309-1-fujita.tomonori@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The function Device::from_raw() increments a refcount by a call to
bindings::get_device(ptr). This can be confused because usually
from_raw() functions don't increment a refcount.
Hence, rename Device::from_raw() to avoid confuion with other "from_raw"
semantics.
The new name of function should be "get_device" to be consistent with
the function get_device() already exist in .c files.
This function body also changed, because the `into()` will convert the
`&'a Device` into `ARef<Device>` and also call `inc_ref` from the
`AlwaysRefCounted` trait implemented for Device.
Signed-off-by: Guilherme Giacomo Simoes <trintaeoitogc@gmail.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Closes: https://github.com/Rust-for-Linux/linux/issues/1088
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20241001205603.106278-1-trintaeoitogc@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Starting with upstream Rust commit a5e3a3f9b6bd ("move
`manual_c_str_literals` to complexity"), to be released in Rust 1.83.0
[1], Clippy now warns on `manual_c_str_literals` by default, e.g.:
error: manually constructing a nul-terminated string
--> rust/kernel/kunit.rs:21:13
|
21 | b"\x013%pA\0".as_ptr() as _,
| ^^^^^^^^^^^^^ help: use a `c""` literal: `c"\x013%pA"`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_c_str_literals
= note: `-D clippy::manual-c-str-literals` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(clippy::manual_c_str_literals)]`
Apply the suggestion to clean up the warnings.
Link: https://github.com/rust-lang/rust-clippy/pull/13263 [1]
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20240927164414.560906-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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>
Adds a wrapper around `kuid_t` called `Kuid`. This allows us to define
various operations on kuids such as equality and current_euid. It also
lets us provide conversions from kuid into userspace values.
Rust Binder needs these operations because it needs to compare kuids for
equality, and it needs to tell userspace about the pid and uid of
incoming transactions.
To read kuids from a `struct task_struct`, you must currently use
various #defines that perform the appropriate field access under an RCU
read lock. Currently, we do not have a Rust wrapper for rcu_read_lock,
which means that for this patch, there are two ways forward:
1. Inline the methods into Rust code, and use __rcu_read_lock directly
rather than the rcu_read_lock wrapper. This gives up lockdep for
these usages of RCU.
2. Wrap the various #defines in helpers and call the helpers from Rust.
This patch uses the second option. One possible disadvantage of the
second option is the possible introduction of speculation gadgets, but
as discussed in [1], the risk appears to be acceptable.
Of course, once a wrapper for rcu_read_lock is available, it is
preferable to use that over either of the two above approaches.
Link: https://lore.kernel.org/all/202312080947.674CD2DC7@keescook/ [1]
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-v10-7-88484f7a3dcf@google.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Allow for the creation of a file descriptor in two steps: first, we
reserve a slot for it, then we commit or drop the reservation. The first
step may fail (e.g., the current process ran out of available slots),
but commit and drop never fail (and are mutually exclusive).
This is needed by Rust Binder when fds are sent from one process to
another. It has to be a two-step process to properly handle the case
where multiple fds are sent: The operation must fail or succeed
atomically, which we achieve by first reserving the fds we need, and
only installing the files once we have reserved enough fds to send the
files.
Fd reservations assume that the value of `current` does not change
between the call to get_unused_fd_flags and the call to fd_install (or
put_unused_fd). By not implementing the Send trait, this abstraction
ensures that the `FileDescriptorReservation` cannot be moved into a
different process.
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240915-alice-file-v10-6-88484f7a3dcf@google.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Add an abstraction for viewing the string representation of a security
context.
This is needed by Rust Binder because it has a feature where a process
can view the string representation of the security context for incoming
transactions. The process can use that to authenticate incoming
transactions, and since the feature is provided by the kernel, the
process can trust that the security context is legitimate.
This abstraction makes the following assumptions about the C side:
* When a call to `security_secid_to_secctx` is successful, it returns a
pointer and length. The pointer references a byte string and is valid
for reading for that many bytes.
* The string may be referenced until `security_release_secctx` is
called.
* If CONFIG_SECURITY is set, then the three methods mentioned in
rust/helpers are available without a helper. (That is, they are not a
#define or `static inline`.)
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240915-alice-file-v10-5-88484f7a3dcf@google.com
Acked-by: Paul Moore <paul@paul-moore.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Add a wrapper around `struct cred` called `Credential`, and provide
functionality to get the `Credential` associated with a `File`.
Rust Binder must check the credentials of processes when they attempt to
perform various operations, and these checks usually take a
`&Credential` as parameter. The security_binder_set_context_mgr function
would be one example. This patch is necessary to access these security_*
methods from Rust.
This Rust abstraction makes the following assumptions about the C side:
* `struct cred` is refcounted with `get_cred`/`put_cred`.
* It's okay to transfer a `struct cred` across threads, that is, you do
not need to call `put_cred` on the same thread as where you called
`get_cred`.
* The `euid` field of a `struct cred` never changes after
initialization.
* The `f_cred` field of a `struct file` never changes after
initialization.
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.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-v10-4-88484f7a3dcf@google.com
Reviewed-by: Kees Cook <kees@kernel.org>
Reviewed-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This abstraction makes it possible to manipulate the open files for a
process. The new `File` struct wraps the C `struct file`. When accessing
it using the smart pointer `ARef<File>`, the pointer will own a
reference count to the file. When accessing it as `&File`, then the
reference does not own a refcount, but the borrow checker will ensure
that the reference count does not hit zero while the `&File` is live.
Since this is intended to manipulate the open files of a process, we
introduce an `fget` constructor that corresponds to the C `fget`
method. In future patches, it will become possible to create a new fd in
a process and bind it to a `File`. Rust Binder will use these to send
fds from one process to another.
We also provide a method for accessing the file's flags. Rust Binder
will use this to access the flags of the Binder fd to check whether the
non-blocking flag is set, which affects what the Binder ioctl does.
This introduces a struct for the EBADF error type, rather than just
using the Error type directly. This has two advantages:
* `File::fget` returns a `Result<ARef<File>, BadFdError>`, which the
compiler will represent as a single pointer, with null being an error.
This is possible because the compiler understands that `BadFdError`
has only one possible value, and it also understands that the
`ARef<File>` smart pointer is guaranteed non-null.
* Additionally, we promise to users of the method that the method can
only fail with EBADF, which means that they can rely on this promise
without having to inspect its implementation.
That said, there are also two disadvantages:
* Defining additional error types involves boilerplate.
* The question mark operator will only utilize the `From` trait once,
which prevents you from using the question mark operator on
`BadFdError` in methods that return some third error type that the
kernel `Error` is convertible into. (However, it works fine in methods
that return `Error`.)
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Co-developed-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240915-alice-file-v10-3-88484f7a3dcf@google.com
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Introduces a safe function for getting a raw pointer to the current
task.
When writing bindings that need to access the current task, it is often
more convenient to call a method that directly returns a raw pointer
than to use the existing `Task::current` method. However, the only way
to do that is `bindings::get_current()` which is unsafe since it calls
into C. By introducing `Task::current_raw()`, it becomes possible to
obtain a pointer to the current task without using unsafe.
Link: https://lore.kernel.org/all/CAH5fLgjT48X-zYtidv31mox3C4_Ogoo_2cBOCmX0Ang3tAgGHA@mail.gmail.com/
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240915-alice-file-v10-2-88484f7a3dcf@google.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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>
In case CONFIG_PREEMPT_RT is enabled __mutex_init() becomes a macro
instead of an extern function (simplified from
include/linux/mutex.h):
#ifndef CONFIG_PREEMPT_RT
extern void __mutex_init(struct mutex *lock, const char *name,
struct lock_class_key *key);
#else
#define __mutex_init(mutex, name, key) \
do { \
rt_mutex_base_init(&(mutex)->rtmutex); \
__mutex_rt_init((mutex), name, key); \
} while (0)
#endif
The macro isn't resolved by bindgen, then. What results in a build
error:
error[E0425]: cannot find function `__mutex_init` in crate `bindings`
--> rust/kernel/sync/lock/mutex.rs:104:28
|
104 | unsafe { bindings::__mutex_init(ptr, name, key) }
| ^^^^^^^^^^^^ help: a function with a similar name exists: `__mutex_rt_init`
|
::: rust/bindings/bindings_generated.rs:23722:5
|
23722 | / pub fn __mutex_rt_init(
23723 | | lock: *mut mutex,
23724 | | name: *const core::ffi::c_char,
23725 | | key: *mut lock_class_key,
23726 | | );
| |_____- similarly named function `__mutex_rt_init` defined here
Fix this by adding a helper.
As explained by Gary Guo in [1] no #ifdef CONFIG_PREEMPT_RT
is needed here as rust/bindings/lib.rs prefers externed function to
helpers if an externed function exists.
Reported-by: Conor Dooley <conor@kernel.org>
Link: https://lore.kernel.org/rust-for-linux/20240913-shack-estate-b376a65921b1@spud/
Link: https://lore.kernel.org/rust-for-linux/20240915123626.1a170103.gary@garyguo.net/ [1]
Fixes: 6d20d629c6 ("rust: lock: introduce `Mutex`")
Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20240916073752.3123484-1-dirk.behme@de.bosch.com
[ Reworded to include the proper example by Dirk. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
We use const helpers in form of
const size_t RUST_CONST_HELPER_ARCH_SLAB_MINALIGN = ARCH_SLAB_MINALIGN;
to aid generation of constants by bindgen because it is otherwise a
macro definition of an expression and bindgen doesn't expand the
constant. The helpers are then have `RUST_CONST_HELPER` prefix stripped
and exposed to Rust code as if `ARCH_SLAB_MISALIGN` is generated
natively by bindgen.
This works well for most constants, but on RISC-V, `ARCH_SLAB_MINALIGN`
is defined directly as literal constant if `!CONFIG_MMU`, and bindgen
would generate `ARCH_SLAB_MINALIGN` directly, thus conflict with the
one generated through the helper.
To fix this, we simply need to block bindgen from generating directly
without going through helper.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202409160804.eSg9zh1e-lkp@intel.com/
Signed-off-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Christian Schrefl <chrisi.schrefl@gmail.com>
Link: https://lore.kernel.org/r/20240916003347.1744345-1-gary@garyguo.net
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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>
Toolchain and infrastructure:
- Support 'MITIGATION_{RETHUNK,RETPOLINE,SLS}' (which cleans up objtool
warnings), teach objtool about 'noreturn' Rust symbols and mimic
'___ADDRESSABLE()' for 'module_{init,exit}'. With that, we should be
objtool-warning-free, so enable it to run for all Rust object files.
- KASAN (no 'SW_TAGS'), KCFI and shadow call sanitizer support.
- Support 'RUSTC_VERSION', including re-config and re-build on change.
- Split helpers file into several files in a folder, to avoid conflicts
in it. Eventually those files will be moved to the right places with
the new build system. In addition, remove the need to manually export
the symbols defined there, reusing existing machinery for that.
- Relax restriction on configurations with Rust + GCC plugins to just
the RANDSTRUCT plugin.
'kernel' crate:
- New 'list' module: doubly-linked linked list for use with reference
counted values, which is heavily used by the upcoming Rust Binder.
This includes 'ListArc' (a wrapper around 'Arc' that is guaranteed
unique for the given ID), 'AtomicTracker' (tracks whether a 'ListArc'
exists using an atomic), 'ListLinks' (the prev/next pointers for an
item in a linked list), 'List' (the linked list itself), 'Iter' (an
iterator over a 'List'), 'Cursor' (a cursor into a 'List' that allows
to remove elements), 'ListArcField' (a field exclusively owned by a
'ListArc'), as well as support for heterogeneous lists.
- New 'rbtree' module: red-black tree abstractions used by the upcoming
Rust Binder. This includes 'RBTree' (the red-black tree itself),
'RBTreeNode' (a node), 'RBTreeNodeReservation' (a memory reservation
for a node), 'Iter' and 'IterMut' (immutable and mutable iterators),
'Cursor' (bidirectional cursor that allows to remove elements), as
well as an entry API similar to the Rust standard library one.
- 'init' module: add 'write_[pin_]init' methods and the 'InPlaceWrite'
trait. Add the 'assert_pinned!' macro.
- 'sync' module: implement the 'InPlaceInit' trait for 'Arc' by
introducing an associated type in the trait.
- 'alloc' module: add 'drop_contents' method to 'BoxExt'.
- 'types' module: implement the 'ForeignOwnable' trait for
'Pin<Box<T>>' and improve the trait's documentation. In addition,
add the 'into_raw' method to the 'ARef' type.
- 'error' module: in preparation for the upcoming Rust support for
32-bit architectures, like arm, locally allow Clippy lint for those.
Documentation:
- https://rust.docs.kernel.org has been announced, so link to it.
- Enable rustdoc's "jump to definition" feature, making its output a
bit closer to the experience in a cross-referencer.
- Debian Testing now also provides recent Rust releases (outside of
the freeze period), so add it to the list.
MAINTAINERS:
- Trevor is joining as reviewer of the "RUST" entry.
And a few other small bits.
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Merge tag 'rust-6.12' of https://github.com/Rust-for-Linux/linux
Pull Rust updates from Miguel Ojeda:
"Toolchain and infrastructure:
- Support 'MITIGATION_{RETHUNK,RETPOLINE,SLS}' (which cleans up
objtool warnings), teach objtool about 'noreturn' Rust symbols and
mimic '___ADDRESSABLE()' for 'module_{init,exit}'. With that, we
should be objtool-warning-free, so enable it to run for all Rust
object files.
- KASAN (no 'SW_TAGS'), KCFI and shadow call sanitizer support.
- Support 'RUSTC_VERSION', including re-config and re-build on
change.
- Split helpers file into several files in a folder, to avoid
conflicts in it. Eventually those files will be moved to the right
places with the new build system. In addition, remove the need to
manually export the symbols defined there, reusing existing
machinery for that.
- Relax restriction on configurations with Rust + GCC plugins to just
the RANDSTRUCT plugin.
'kernel' crate:
- New 'list' module: doubly-linked linked list for use with reference
counted values, which is heavily used by the upcoming Rust Binder.
This includes 'ListArc' (a wrapper around 'Arc' that is guaranteed
unique for the given ID), 'AtomicTracker' (tracks whether a
'ListArc' exists using an atomic), 'ListLinks' (the prev/next
pointers for an item in a linked list), 'List' (the linked list
itself), 'Iter' (an iterator over a 'List'), 'Cursor' (a cursor
into a 'List' that allows to remove elements), 'ListArcField' (a
field exclusively owned by a 'ListArc'), as well as support for
heterogeneous lists.
- New 'rbtree' module: red-black tree abstractions used by the
upcoming Rust Binder.
This includes 'RBTree' (the red-black tree itself), 'RBTreeNode' (a
node), 'RBTreeNodeReservation' (a memory reservation for a node),
'Iter' and 'IterMut' (immutable and mutable iterators), 'Cursor'
(bidirectional cursor that allows to remove elements), as well as
an entry API similar to the Rust standard library one.
- 'init' module: add 'write_[pin_]init' methods and the
'InPlaceWrite' trait. Add the 'assert_pinned!' macro.
- 'sync' module: implement the 'InPlaceInit' trait for 'Arc' by
introducing an associated type in the trait.
- 'alloc' module: add 'drop_contents' method to 'BoxExt'.
- 'types' module: implement the 'ForeignOwnable' trait for
'Pin<Box<T>>' and improve the trait's documentation. In addition,
add the 'into_raw' method to the 'ARef' type.
- 'error' module: in preparation for the upcoming Rust support for
32-bit architectures, like arm, locally allow Clippy lint for
those.
Documentation:
- https://rust.docs.kernel.org has been announced, so link to it.
- Enable rustdoc's "jump to definition" feature, making its output a
bit closer to the experience in a cross-referencer.
- Debian Testing now also provides recent Rust releases (outside of
the freeze period), so add it to the list.
MAINTAINERS:
- Trevor is joining as reviewer of the "RUST" entry.
And a few other small bits"
* tag 'rust-6.12' of https://github.com/Rust-for-Linux/linux: (54 commits)
kasan: rust: Add KASAN smoke test via UAF
kbuild: rust: Enable KASAN support
rust: kasan: Rust does not support KHWASAN
kbuild: rust: Define probing macros for rustc
kasan: simplify and clarify Makefile
rust: cfi: add support for CFI_CLANG with Rust
cfi: add CONFIG_CFI_ICALL_NORMALIZE_INTEGERS
rust: support for shadow call stack sanitizer
docs: rust: include other expressions in conditional compilation section
kbuild: rust: replace proc macros dependency on `core.o` with the version text
kbuild: rust: rebuild if the version text changes
kbuild: rust: re-run Kconfig if the version text changes
kbuild: rust: add `CONFIG_RUSTC_VERSION`
rust: avoid `box_uninit_write` feature
MAINTAINERS: add Trevor Gross as Rust reviewer
rust: rbtree: add `RBTree::entry`
rust: rbtree: add cursor
rust: rbtree: add mutable iterator
rust: rbtree: add iterator
rust: rbtree: add red-black tree implementation backed by the C version
...
Make it possible to use the Control Flow Integrity (CFI) sanitizer when
Rust is enabled. Enabling CFI with Rust requires that CFI is configured
to normalize integer types so that all integer types of the same size
and signedness are compatible under CFI.
Rust and C use the same LLVM backend for code generation, so Rust KCFI
is compatible with the KCFI used in the kernel for C. In the case of
FineIBT, CFI also depends on -Zpatchable-function-entry for rewriting
the function prologue, so we set that flag for Rust as well. The flag
for FineIBT requires rustc 1.80.0 or later, so include a Kconfig
requirement for that.
Enabling Rust will select CFI_ICALL_NORMALIZE_INTEGERS because the flag
is required to use Rust with CFI. Using select rather than `depends on`
avoids the case where Rust is not visible in menuconfig due to
CFI_ICALL_NORMALIZE_INTEGERS not being enabled. One disadvantage of
select is that RUST must `depends on` all of the things that
CFI_ICALL_NORMALIZE_INTEGERS depends on to avoid invalid configurations.
Alice has been using KCFI on her phone for several months, so it is
reasonably well tested on arm64.
Signed-off-by: Matthew Maurer <mmaurer@google.com>
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Gatlin Newhouse <gatlin.newhouse@gmail.com>
Acked-by: Kees Cook <kees@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240801-kcfi-v2-2-c93caed3d121@google.com
[ Replaced `!FINEIBT` requirement with `!CALL_PADDING` to prevent
a build error on older Rust compilers. Fixed typo. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
With the `RUSTC_VERSION_TEXT` rebuild support in place, now proc macros
can depend on that instead of `core.o`.
This means that both the `core` and `macros` crates can be built in
parallel, and that touching `core.o` does not trigger a rebuild of the
proc macros.
This could be accomplished using the same approach as for `core`
(i.e. depending directly on `include/config/RUSTC_VERSION_TEXT`). However,
that is considered an implementation detail [1], and thus it is best
to avoid it. Instead, let fixdep find a string that we explicitly
write down in the source code for this purpose (like it is done for
`include/linux/compiler-version.h`), which we can easily do (unlike for
`core`) since this is our own source code.
Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/rust-for-linux/CAK7LNAQBG0nDupXSgAAk-6nOqeqGVkr3H1RjYaqRJ1OxmLm6xA@mail.gmail.com/ [1]
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Tested-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20240902165535.1101978-5-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Now that `RUSTC_VERSION_TEXT` exists, use it to rebuild `core` when the
version text changes (which in turn will trigger a rebuild of all the
kernel Rust code).
This also applies to proc macros (which only work with the `rustc` that
compiled them), via the already existing dependency on `core.o`. That
is cleaned up in the next commit.
However, this does not cover host programs written in Rust, which is
the same case in the C side.
This is accomplished by referencing directly the generated file, instead
of using the `fixdep` header trick, since we cannot change the Rust
standard library sources. This is not too much of a burden, since it
only needs to be done for `core`.
Tested-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20240902165535.1101978-4-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Currently while defining `THIS_MODULE` symbol in `module!()`, the
pointer used to construct `ThisModule` is derived from an immutable
reference of `__this_module`, which means the pointer doesn't have
the provenance for writing, and that means any write to that pointer
is UB regardless of data races or not. However, the usage of
`THIS_MODULE` includes passing this pointer to functions that may write
to it (probably in unsafe code), and this will create soundness issues.
One way to fix this is using `addr_of_mut!()` but that requires the
unstable feature "const_mut_refs". So instead of `addr_of_mut()!`,
an extern static `Opaque` is used here: since `Opaque<T>` is transparent
to `T`, an extern static `Opaque` will just wrap the C symbol (defined
in a C compile unit) in an `Opaque`, which provides a pointer with
writable provenance via `Opaque::get()`. This fix the potential UBs
because of pointer provenance unmatched.
Reported-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Gary Guo <gary@garyguo.net>
Closes: https://rust-for-linux.zulipchat.com/#narrow/stream/x/topic/x/near/465412664
Fixes: 1fbde52bde ("rust: add `macros` crate")
Cc: stable@vger.kernel.org # 6.6.x: be2ca1e039: ("rust: types: Make Opaque::get const")
Link: https://lore.kernel.org/r/20240828180129.4046355-1-boqun.feng@gmail.com
[ Fixed two typos, reworded title. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This mirrors the entry API [1] from the Rust standard library on
`RBTree`. This API can be used to access the entry at a specific key and
make modifications depending on whether the key is vacant or occupied.
This API is useful because it can often be used to avoid traversing the
tree multiple times.
This is used by binder to look up and conditionally access or insert a
value, depending on whether it is there or not [2].
Link: https://doc.rust-lang.org/stable/std/collections/btree_map/enum.Entry.html [1]
Link: https://android-review.googlesource.com/c/kernel/common/+/2849906 [2]
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Tested-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Matt Gilbride <mattgilbride@google.com>
Link: https://lore.kernel.org/r/20240822-b4-rbtree-v12-5-014561758a57@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Add a cursor interface to `RBTree`, supporting the following use cases:
- Inspect the current node pointed to by the cursor, inspect/move to
it's neighbors in sort order (bidirectionally).
- Mutate the tree itself by removing the current node pointed to by the
cursor, or one of its neighbors.
Add functions to obtain a cursor to the tree by key:
- The node with the smallest key
- The node with the largest key
- The node matching the given key, or the one with the next larger key
The cursor abstraction is needed by the binder driver to efficiently
search for nodes and (conditionally) modify them, as well as their
neighbors [1].
Link: https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-6-08ba9197f637@google.com/ [1]
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Tested-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Matt Gilbride <mattgilbride@google.com>
Link: https://lore.kernel.org/r/20240822-b4-rbtree-v12-4-014561758a57@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Add mutable Iterator implementation for `RBTree`,
allowing iteration over (key, value) pairs in key order. Only values are
mutable, as mutating keys implies modifying a node's position in the tree.
Mutable iteration is used by the binder driver during shutdown to
clean up the tree maintained by the "range allocator" [1].
Link: https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-6-08ba9197f637@google.com/ [1]
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Tested-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Matt Gilbride <mattgilbride@google.com>
Link: https://lore.kernel.org/r/20240822-b4-rbtree-v12-3-014561758a57@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
- Add Iterator implementation for `RBTree`, allowing
iteration over (key, value) pairs in key order.
- Add individual `keys()` and `values()` functions to iterate over keys
or values alone.
- Update doctests to use iteration instead of explicitly getting items.
Iteration is needed by the binder driver to enumerate all values in a
tree for oneway spam detection [1].
Link: https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-17-08ba9197f637@google.com/ [1]
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Tested-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Matt Gilbride <mattgilbride@google.com>
Link: https://lore.kernel.org/r/20240822-b4-rbtree-v12-2-014561758a57@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
The rust rbtree exposes a map-like interface over keys and values,
backed by the kernel red-black tree implementation. Values can be
inserted, deleted, and retrieved from a `RBTree` by key.
This base abstraction is used by binder to store key/value
pairs and perform lookups, for example the patch
"[PATCH RFC 03/20] rust_binder: add threading support"
in the binder RFC [1].
Link: https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-3-08ba9197f637@google.com/ [1]
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Tested-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Matt Gilbride <mattgilbride@google.com>
Link: https://lore.kernel.org/r/20240822-b4-rbtree-v12-1-014561758a57@google.com
[ Updated link to docs.kernel.org. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Add unified genphy_read_status function for C22 and C45
registers. Instead of having genphy_c22 and genphy_c45 methods, this
unifies genphy_read_status functions for C22 and C45.
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add the unified read/write API for C22 and C45 registers. The
abstractions support access to only C22 registers now. Instead of
adding read/write_c45 methods specifically for C45, a new reg module
supports the unified API to access C22 and C45 registers with trait,
by calling an appropriate phylib functions.
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Implement AsRef<kernel::device::Device> trait for Device. A PHY driver
needs a reference to device::Device to call the firmware API.
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Support phy_driver probe callback, used to set up device-specific
structures.
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add rust equivalent to include/linux/sizes.h, makes code more
readable. Only SZ_*K that QT2025 PHY driver uses are added.
Make generated constants accessible with a proper type.
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Upstream Rust's libs-api team has consensus for stabilizing some of
`feature(new_uninit)`, but not for `Box<MaybeUninit<T>>::write`. Instead,
we can use `MaybeUninit<T>::write`, so Rust for Linux can drop the
feature after stabilization. That will happen after merging, as the FCP
has completed [1].
This is required before stabilization because remaining-unstable API
will be divided into new features. This code doesn't know about those
yet. It can't: they haven't landed, as the relevant PR is blocked on
rustc's CI testing Rust-for-Linux without this patch.
[ The PR has landed [2] and will be released in Rust 1.82.0 (expected on
2024-10-17), so we could conditionally enable the new unstable feature
(`box_uninit_write` [3]) instead, but just for a single `unsafe` block
it is probably not worth it. For the time being, I added it to the
"nice to have" section of our unstable features list. - Miguel ]
Link: https://github.com/rust-lang/rust/issues/63291#issuecomment-2183022955 [1]
Link: https://github.com/rust-lang/rust/pull/129416 [2]
Link: https://github.com/rust-lang/rust/issues/129397 [3]
Signed-off-by: Jubilee Young <workingjubilee@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
[ Reworded slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
In Rust 1.56.0 [1], rustdoc introduced the "jump to definition"
feature [2], i.e. the unstable flag `--generate-link-to-definition`.
It adds links to the source view of the documentation.
For instance, in the source view of `rust/kernel/sync.rs`, for this code:
impl Default for LockClassKey {
fn default() -> Self {
Self::new()
}
}
It will add three hyperlinks:
- `Default` points to the rendered "Trait `core::default::Default`"
page (not the source view, since it goes to another crate, though
this may change).
- `LockClassKey` points to the `pub struct LockClassKey(...);` line
in the same page, highlighting the line number.
- `Self::new()` points to the `pub const fn new() -> Self { ... }`
associated function, highlighting its line numbers (i.e. for the
full function).
This makes the source view more useful and a bit closer to the experience
in e.g. the Elixir Cross Referencer [3].
I have provisionally enabled it for rust.docs.kernel.org [4] -- one can
take a look at the source view there for an example of how it looks like.
Thus enable it.
Cc: Guillaume Gomez <guillaume1.gomez@gmail.com>
Link: https://github.com/rust-lang/rust/pull/84176 [1]
Link: https://github.com/rust-lang/rust/issues/89095 [2]
Link: https://elixir.bootlin.com [3]
Link: https://rust.docs.kernel.org [4]
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20240818141249.387166-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Add a method for `ARef` that is analogous to `Arc::into_raw`. It is the
inverse operation of `ARef::from_raw`, and allows you to convert the
`ARef` back into a raw pointer while retaining ownership of the
refcount.
This new function will be used by [1] for converting the type in an
`ARef` using `ARef::from_raw(ARef::into_raw(me).cast())`. Alice has
also needed the same function for other use-cases in the past, but [1]
is the first to go upstream.
This was implemented independently by Kartik and Alice. The two versions
were merged by Alice, so all mistakes are Alice's.
Link: https://lore.kernel.org/r/20240801-vma-v3-1-db6c1c0afda9@google.com [1]
Link: https://github.com/Rust-for-Linux/linux/issues/1044
Signed-off-by: Kartik Prajapati <kartikprajapati987@gmail.com>
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
[ Reworded to correct the author reference and changed tag to Link
since it is not a bug. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Use links to docs.kernel.org instead of www.kernel.org/doc/html/latest
in the code documentation. The links are shorter and cleaner.
Link: https://github.com/Rust-for-Linux/linux/issues/1101
Signed-off-by: Michael Vetter <jubalh@iodoru.org>
[ Reworded slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
One way to explain what `ListArc` does is that it controls exclusive
access to the prev/next pointer field in a refcounted object. The
feature of having a special reference to a refcounted object with
exclusive access to specific fields is useful for other things, so
provide a general utility for that.
This is used by Rust Binder to keep track of which processes have a
reference to a given node. This involves an object for each process/node
pair, that is referenced by both the process and the node. For some
fields in this object, only the process's reference needs to access
them (and it needs mutable access), so Binder uses a ListArc to give the
process's reference exclusive access.
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240814-linked-list-v5-10-f5f5e8075da0@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Support linked lists that can hold many different structs at once. This
is generally done using trait objects. The main challenge is figuring
what the struct is given only a pointer to the ListLinks.
We do this by storing a pointer to the struct next to the ListLinks
field. The container_of operation will then just read that pointer. When
the type is a trait object, that pointer will be a fat pointer whose
metadata is a vtable that tells you what kind of struct it is.
Heterogeneous lists are heavily used by Rust Binder. There are a lot of
so-called todo lists containing various events that need to be delivered
to userspace next time userspace calls into the driver. And there are
quite a few different todo item types: incoming transaction, changes to
refcounts, death notifications, and more.
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240814-linked-list-v5-9-f5f5e8075da0@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
The cursor is very similar to the list iterator, but it has one
important feature that the iterator doesn't: it can be used to remove
items from the linked list.
This feature cannot be added to the iterator because the references you
get from the iterator are considered borrows of the original list,
rather than borrows of the iterator. This means that there's no way to
prevent code like this:
let item = iter.next();
iter.remove();
use(item);
If `iter` was a cursor instead of an iterator, then `item` will be
considered a borrow of `iter`. Since `remove` destroys `iter`, this
means that the borrow-checker will prevent uses of `item` after the call
to `remove`.
So there is a trade-off between supporting use in traditional for loops,
and supporting removal of elements as you iterate. Iterators and cursors
represents two different choices on that spectrum.
Rust Binder needs cursors for the list of death notifications that a
process is currently handling. When userspace tells Binder that it has
finished processing the death notification, Binder will iterate the list
to search for the relevant item and remove it.
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240814-linked-list-v5-8-f5f5e8075da0@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Rust Binder has lists containing stuff such as all contexts or all
processes, and sometimes needs to iterate over them. This patch enables
Rust Binder to do that using a normal for loop.
The iterator returns the ArcBorrow type, so it is possible to grab a
refcount to values while iterating.
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240814-linked-list-v5-7-f5f5e8075da0@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Add the actual linked list itself.
The linked list uses the following design: The List type itself just has
a single pointer to the first element of the list. And the actual list
items then form a cycle. So the last item is `first->prev`.
This is slightly different from the usual kernel linked list. Matching
that exactly would amount to giving List two pointers, and having it be
part of the cycle of items. This alternate design has the advantage that
the cycle is never completely empty, which can reduce the number of
branches in some cases. However, it also has the disadvantage that List
must be pinned, which this design is trying to avoid.
Having the list items form a cycle rather than having null pointers at
the beginning/end is convenient for several reasons. For one, it lets us
store only one pointer in List, and it simplifies the implementation of
several functions.
Unfortunately, the `remove` function that removes an arbitrary element
from the list has to be unsafe. This is needed because there is no way
to handle the case where you pass an element from the wrong list. For
example, if it is the first element of some other list, then that other
list's `first` pointer would not be updated. Similarly, it could be a
data race if you try to remove it from two different lists in parallel.
(There's no problem with passing `remove` an item that's not in any
list. Additionally, other removal methods such as `pop_front` need not
be unsafe, as they can't be used to remove items from another list.)
A future patch in this series will introduce support for cursors that
can be used to remove arbitrary items without unsafe code.
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240814-linked-list-v5-6-f5f5e8075da0@google.com
[ Fixed a few typos. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Adds a macro for safely implementing the ListItem trait. As part of the
implementation of the macro, we also provide a HasListLinks trait
similar to the workqueue's HasWorkItem trait.
The HasListLinks trait is only necessary if you are implementing
ListItem using the impl_list_item macro.
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240814-linked-list-v5-5-f5f5e8075da0@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Define the ListLinks struct, which wraps the prev/next pointers that
will be used to insert values into a List in a future patch. Also
define the ListItem trait, which is implemented by structs that have a
ListLinks field.
The ListItem trait provides four different methods that are all
essentially container_of or the reverse of container_of. Two of them are
used before inserting/after removing an item from the list, and the two
others are used when looking at a value without changing whether it is
in a list. This distinction is introduced because it is needed for the
patch that adds support for heterogeneous lists, which are implemented
by adding a third pointer field with a fat pointer to the full struct.
When inserting into the heterogeneous list, the pointer-to-self is
updated to have the right vtable, and the container_of operation is
implemented by just returning that pointer instead of using the real
container_of operation.
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240814-linked-list-v5-4-f5f5e8075da0@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Add the ability to track whether a ListArc exists for a given value,
allowing for the creation of ListArcs without going through UniqueArc.
The `impl_list_arc_safe!` macro is extended with a `tracked_by` strategy
that defers the tracking of ListArcs to a field of the struct.
Additionally, the AtomicListArcTracker type is introduced, which can
track whether a ListArc exists using an atomic. By deferring the
tracking to a field of type AtomicListArcTracker, structs gain the
ability to create ListArcs without going through a UniqueArc.
Rust Binder uses this for some objects where we want to be able to
insert them into a linked list at any time. Using the
AtomicListArcTracker, we are able to check whether an item is already in
the list, and if not, we can create a `ListArc` and push it.
The macro has the ability to defer the tracking of ListArcs to a field,
using whatever strategy that field has. Since we don't add any
strategies other than AtomicListArcTracker, another similar option would
be to hard-code that the field should be an AtomicListArcTracker.
However, Rust Binder has a case where the AtomicListArcTracker is not
stored directly in the struct, but in a sub-struct. Furthermore, the
outer struct is generic:
struct Wrapper<T: ?Sized> {
links: ListLinks,
inner: T,
}
Here, the Wrapper struct implements ListArcSafe with `tracked_by inner`,
and then the various types used with `inner` also uses the macro to
implement ListArcSafe. Some of them use the untracked strategy, and some
of them use tracked_by with an AtomicListArcTracker. This way, Wrapper
just inherits whichever choice `inner` has made.
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240814-linked-list-v5-3-f5f5e8075da0@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
The `ListArc` type can be thought of as a special reference to a
refcounted object that owns the permission to manipulate the
`next`/`prev` pointers stored in the refcounted object. By ensuring that
each object has only one `ListArc` reference, the owner of that
reference is assured exclusive access to the `next`/`prev` pointers.
When a `ListArc` is inserted into a `List`, the `List` takes ownership
of the `ListArc` reference.
There are various strategies for ensuring that a value has only one
`ListArc` reference. The simplest is to convert a `UniqueArc` into a
`ListArc`. However, the refcounted object could also keep track of
whether a `ListArc` exists using a boolean, which could allow for the
creation of new `ListArc` references from an `Arc` reference. Whatever
strategy is used, the relevant tracking is referred to as "the tracking
inside `T`", and the `ListArcSafe` trait (and its subtraits) are used to
update the tracking when a `ListArc` is created or destroyed.
Note that we allow the case where the tracking inside `T` thinks that a
`ListArc` exists, but actually, there isn't a `ListArc`. However, we do
not allow the opposite situation where a `ListArc` exists, but the
tracking thinks it doesn't. This is because the former can at most
result in us failing to create a `ListArc` when the operation could
succeed, whereas the latter can result in the creation of two `ListArc`
references. Only the latter situation can lead to memory safety issues.
This patch introduces the `impl_list_arc_safe!` macro that allows you to
implement `ListArcSafe` for types using the strategy where a `ListArc`
can only be created from a `UniqueArc`. Other strategies are introduced
in later patches.
This is part of the linked list that Rust Binder will use for many
different things. The strategy where a `ListArc` can only be created
from a `UniqueArc` is actually sufficient for most of the objects that
Rust Binder needs to insert into linked lists. Usually, these are todo
items that are created and then immediately inserted into a queue.
The const generic ID allows objects to have several prev/next pointer
pairs so that the same object can be inserted into several different
lists. You are able to have several `ListArc` references as long as they
correspond to different pointer pairs. The ID itself is purely a
compile-time concept and will not be present in the final binary. Both
the `List` and the `ListArc` will need to agree on the ID for them to
work together. Rust Binder uses this in a few places (e.g. death
recipients) where the same object can be inserted into both generic todo
lists and some other lists for tracking the status of the object.
The ID is a const generic rather than a type parameter because the
`pair_from_unique` method needs to be able to assert that the two ids
are different. There's no easy way to assert that when using types
instead of integers.
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240814-linked-list-v5-2-f5f5e8075da0@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Add a macro to statically check if a field of a struct is marked with
`#[pin]` ie that it is structurally pinned. This can be used when
`unsafe` code needs to rely on fields being structurally pinned.
The macro has a special "inline" mode for the case where the type
depends on generic parameters from the surrounding scope.
Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240814-linked-list-v5-1-f5f5e8075da0@google.com
[ Replaced `compile_fail` with `ignore` and a TODO note. Removed
`pub` from example to clean `unreachable_pub` lint. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Sometimes it is necessary to split allocation and initialization into
two steps. One such situation is when reusing existing allocations
obtained via `Box::drop_contents`. See [1] for an example.
In order to support this use case add `write_[pin_]init` functions to the
pin-init API. These functions operate on already allocated smart
pointers that wrap `MaybeUninit<T>`.
Link: https://lore.kernel.org/rust-for-linux/f026532f-8594-4f18-9aa5-57ad3f5bc592@proton.me/ [1]
Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20240819112415.99810-2-benno.lossin@proton.me
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Sometimes (see [1]) it is necessary to drop the value inside of a
`Box<T>`, but retain the allocation. For example to reuse the allocation
in the future.
Introduce a new function `drop_contents` that turns a `Box<T>` into
`Box<MaybeUninit<T>>` by dropping the value.
Link: https://lore.kernel.org/rust-for-linux/20240418-b4-rbtree-v3-5-323e134390ce@google.com/ [1]
Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240819112415.99810-1-benno.lossin@proton.me
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
