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a=openpgp-sha256; l=2383; i=aliceryhl@google.com; h=from:subject:message-id; bh=Y7EveGwaFZVeZYYvVcVUkcGhuSESwjRgqqnewAo3pxw=; b=owEBbQKS/ZANAwAKAQRYvu5YxjlGAcsmYgBmomDXe7TQovfSy+bcM+80aWs50pz7TKA1NVt2F dKLuFFnsZ2JAjMEAAEKAB0WIQSDkqKUTWQHCvFIvbIEWL7uWMY5RgUCZqJg1wAKCRAEWL7uWMY5 RpJIEAC1c3zbht1aNR9FY2+6fNMS99tzB2GUHPJaEdtuUJ4ILd1Eg60NRfZuOdJcp58SdE75C4R DxcTruQkGWaQ6GUOHi9LcnOfO3YgxzHKdjnFeZ2XRdB4o6kP+V4oaT4h9GI0TmllzHOl0iAcP7y iCJe5J+1zEo2PUPeR5sq1dJhzJ1gisMMlqu/kdCZ0hZhpHI3OEF+RPnb2CfZrSGm6ywXyLtrRGT X9idZihV/78sRUhhwXb1OU5xaJgrd2ltriARLf66c4dI/jkqurNSSWMgYZhoAZq4o4BjXuQoVXK kqjrAK06BgJLj2sKp8GR4QqRoZha6rndpSyDkUIfOi1MqFgJLpMUW0Z/SBLyap9Ya56+zsemE2J LzWfzOAT76t8xTPDvN9pNG1jKHgsNGYBFSRyraWlUtVZD7YD7o8Zk6LSP3cF4bDdc7DIJOlKFWh U6IDSZ575oMK4ltRD7KwcKnioadJrujgwOJCobcqzSkRVs5cQ5KNOW4LG9OyBEkhdj6bj32CLHh Ry7preBUES11aSl79B8RNZnVgoD8PRXx0RkXS6lsY914s60hjcYDMDi6PdjCVYhOFGWg1BimRf/ O48jMkZXjXyM2HA8rSAFAwwAhFfyzQSIOKc50Q/E0Go2O+gM2Nd4pzF2WvZxI+Mmq+i3d8zcOLg F/mNAgZB1cBXWOA== X-Mailer: b4 0.13-dev-26615 Message-ID: <20240725-alice-file-v8-2-55a2e80deaa8@google.com> Subject: [PATCH v8 2/8] rust: task: add `Task::current_raw` From: Alice Ryhl To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , "=?utf-8?q?Bj=C3=B6rn_Roy_Baron?=" , Benno Lossin , Andreas Hindborg , Peter Zijlstra , Alexander Viro , Christian Brauner , Greg Kroah-Hartman , "=?utf-8?q?Arve_Hj=C3=B8nnev=C3=A5g?=" , Todd Kjos , Martijn Coenen , Joel Fernandes , Carlos Llamas , Suren Baghdasaryan Cc: Dan Williams , Matthew Wilcox , Thomas Gleixner , Daniel Xu , Martin Rodriguez Reboredo , Trevor Gross , linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-fsdevel@vger.kernel.org, Alice Ryhl , Kees Cook Content-Type: text/plain; charset="utf-8" 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 Reviewed-by: Martin Rodriguez Reboredo Reviewed-by: Trevor Gross Signed-off-by: Alice Ryhl --- rust/kernel/task.rs | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs index 278c623de0c6..367b4bbddd9f 100644 --- a/rust/kernel/task.rs +++ b/rust/kernel/task.rs @@ -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, } } -- 2.45.2.1089.g2a221341d9-goog