Unverified Commit 913f8cf4 authored Sep 15, 2024 by Alice Ryhl Committed by Christian Brauner Sep 30, 2024

rust: task: add `Task::current_raw`

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>

parent e7572e5d

rust/kernel/task.rs

+11 −4

Original line number	Diff line number	Diff line
		@@ -97,6 +97,15 @@ unsafe impl Sync for Task {}
		type Pid = bindings::pid_t;

		impl Task {
		/// Returns a raw pointer to the current task.
		///
		/// It is up to the user to use the pointer correctly.
		#[inline]
		pub fn current_raw() -> *mut bindings::task_struct {
		// SAFETY: Getting the current pointer is always safe.
		unsafe { bindings::get_current() }
		}

		/// Returns a task reference for the currently executing task/thread.
		///
		/// The recommended way to get the current task/thread is to use the
		@@ -119,14 +128,12 @@ fn deref(&self) -> &Self::Target {
		}
		}

		// SAFETY: Just an FFI call with no additional safety requirements.
		let ptr = unsafe { bindings::get_current() };

		let current = Task::current_raw();
		TaskRef {
		// SAFETY: If the current thread is still running, the current task is valid. Given
		// that `TaskRef` is not `Send`, we know it cannot be transferred to another thread
		// (where it could potentially outlive the caller).
		task: unsafe { &*ptr.cast() },
		task: unsafe { &*current.cast() },
		_not_send: NotThreadSafe,
		}
		}