Reintroduce dynamically-allocated LockClassKeys such that they are automatically (de)registered. Require that all usages of LockClassKeys ensure that they are Pin'd. Closes: https://github.com/Rust-for-Linux/linux/issues/1102 Suggested-by: Benno Lossin <benno.lossin@xxxxxxxxx> Suggested-by: Boqun Feng <boqun.feng@xxxxxxxxx> Signed-off-by: Mitchell Levy <levymitchell0@xxxxxxxxx> --- rust/helpers/helpers.c | 1 + rust/helpers/sync.c | 13 ++++++++++ rust/kernel/sync.rs | 57 ++++++++++++++++++++++++++++++++++++++--- rust/kernel/sync/condvar.rs | 5 ++-- rust/kernel/sync/lock.rs | 9 +++---- rust/kernel/sync/lock/global.rs | 5 ++-- rust/kernel/sync/poll.rs | 2 +- rust/kernel/workqueue.rs | 3 ++- 8 files changed, 79 insertions(+), 16 deletions(-) diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c index dcf827a61b52..572af343212c 100644 --- a/rust/helpers/helpers.c +++ b/rust/helpers/helpers.c @@ -25,6 +25,7 @@ #include "signal.c" #include "slab.c" #include "spinlock.c" +#include "sync.c" #include "task.c" #include "uaccess.c" #include "vmalloc.c" diff --git a/rust/helpers/sync.c b/rust/helpers/sync.c new file mode 100644 index 000000000000..ff7e68b48810 --- /dev/null +++ b/rust/helpers/sync.c @@ -0,0 +1,13 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/lockdep.h> + +void rust_helper_lockdep_register_key(struct lock_class_key *k) +{ + lockdep_register_key(k); +} + +void rust_helper_lockdep_unregister_key(struct lock_class_key *k) +{ + lockdep_unregister_key(k); +} diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs index ae16bfd98de2..13bfdc647c5b 100644 --- a/rust/kernel/sync.rs +++ b/rust/kernel/sync.rs @@ -5,6 +5,8 @@ //! This module contains the kernel APIs related to synchronisation that have been ported or //! wrapped for usage by Rust code in the kernel. +use crate::pin_init; +use crate::prelude::*; use crate::types::Opaque; mod arc; @@ -22,15 +24,64 @@ /// Represents a lockdep class. It's a wrapper around C's `lock_class_key`. #[repr(transparent)] -pub struct LockClassKey(Opaque<bindings::lock_class_key>); +#[pin_data(PinnedDrop)] +pub struct LockClassKey { + #[pin] + inner: Opaque<bindings::lock_class_key>, +} // SAFETY: `bindings::lock_class_key` is designed to be used concurrently from multiple threads and // provides its own synchronization. unsafe impl Sync for LockClassKey {} impl LockClassKey { + /// Initializes a dynamically allocated lock class key. In the common case of using a + /// statically allocated lock class key, the static_lock_class! macro should be used instead. + /// + /// # Example + /// ``` + /// # use kernel::{c_str, stack_pin_init}; + /// # use kernel::alloc::KBox; + /// # use kernel::types::ForeignOwnable; + /// # use kernel::sync::{LockClassKey, SpinLock}; + /// + /// let key = KBox::pin_init(LockClassKey::new_dynamic(), GFP_KERNEL)?; + /// let key_ptr = key.into_foreign(); + /// + /// // SAFETY: `key_ptr` is returned by the above `into_foreign()`, whose `from_foreign()` has + /// // not yet been called. + /// stack_pin_init!(let num: SpinLock<u32> = SpinLock::new( + /// 0, + /// c_str!("my_spinlock"), + /// unsafe { <Pin<KBox<LockClassKey>> as ForeignOwnable>::borrow(key_ptr) } + /// )); + /// + /// drop(num); + /// + /// // SAFETY: We dropped `num`, the only use of the key, so the result of the previous + /// // `borrow` has also been dropped. Thus, it's safe to use from_foreign. + /// unsafe { drop(<Pin<KBox<LockClassKey>> as ForeignOwnable>::from_foreign(key_ptr)) }; + /// + /// # Ok::<(), Error>(()) + /// ``` + pub fn new_dynamic() -> impl PinInit<Self> { + pin_init!(Self { + // SAFETY: lockdep_register_key expects an uninitialized block of memory + inner <- Opaque::ffi_init(|slot| unsafe { bindings::lockdep_register_key(slot) }) + }) + } + pub(crate) fn as_ptr(&self) -> *mut bindings::lock_class_key { - self.0.get() + self.inner.get() + } +} + +#[pinned_drop] +impl PinnedDrop for LockClassKey { + fn drop(self: Pin<&mut Self>) { + // SAFETY: self.as_ptr was registered with lockdep and self is pinned, so the address + // hasn't changed. Thus, it's safe to pass to unregister. + unsafe { bindings::lockdep_unregister_key(self.as_ptr()) } } } @@ -43,7 +94,7 @@ macro_rules! static_lock_class { // lock_class_key static CLASS: $crate::sync::LockClassKey = unsafe { ::core::mem::MaybeUninit::uninit().assume_init() }; - &CLASS + $crate::prelude::Pin::static_ref(&CLASS) }}; } diff --git a/rust/kernel/sync/condvar.rs b/rust/kernel/sync/condvar.rs index 7df565038d7d..29289ccf55cc 100644 --- a/rust/kernel/sync/condvar.rs +++ b/rust/kernel/sync/condvar.rs @@ -15,8 +15,7 @@ time::Jiffies, types::Opaque, }; -use core::marker::PhantomPinned; -use core::ptr; +use core::{marker::PhantomPinned, pin::Pin, ptr}; use macros::pin_data; /// Creates a [`CondVar`] initialiser with the given name and a newly-created lock class. @@ -101,7 +100,7 @@ unsafe impl Sync for CondVar {} impl CondVar { /// Constructs a new condvar initialiser. - pub fn new(name: &'static CStr, key: &'static LockClassKey) -> impl PinInit<Self> { + pub fn new(name: &'static CStr, key: Pin<&'static LockClassKey>) -> impl PinInit<Self> { pin_init!(Self { _pin: PhantomPinned, // SAFETY: `slot` is valid while the closure is called and both `name` and `key` have diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs index 41dcddac69e2..119e5f569bdb 100644 --- a/rust/kernel/sync/lock.rs +++ b/rust/kernel/sync/lock.rs @@ -7,12 +7,9 @@ use super::LockClassKey; use crate::{ - init::PinInit, - pin_init, - str::CStr, - types::{NotThreadSafe, Opaque, ScopeGuard}, + init::PinInit, pin_init, str::CStr, types::NotThreadSafe, types::Opaque, types::ScopeGuard, }; -use core::{cell::UnsafeCell, marker::PhantomPinned}; +use core::{cell::UnsafeCell, marker::PhantomPinned, pin::Pin}; use macros::pin_data; pub mod mutex; @@ -121,7 +118,7 @@ unsafe impl<T: ?Sized + Send, B: Backend> Sync for Lock<T, B> {} impl<T, B: Backend> Lock<T, B> { /// Constructs a new lock initialiser. - pub fn new(t: T, name: &'static CStr, key: &'static LockClassKey) -> impl PinInit<Self> { + pub fn new(t: T, name: &'static CStr, key: Pin<&'static LockClassKey>) -> impl PinInit<Self> { pin_init!(Self { data: UnsafeCell::new(t), _pin: PhantomPinned, diff --git a/rust/kernel/sync/lock/global.rs b/rust/kernel/sync/lock/global.rs index 480ee724e3cc..d65f94b5caf2 100644 --- a/rust/kernel/sync/lock/global.rs +++ b/rust/kernel/sync/lock/global.rs @@ -13,6 +13,7 @@ use core::{ cell::UnsafeCell, marker::{PhantomData, PhantomPinned}, + pin::Pin, }; /// Trait implemented for marker types for global locks. @@ -26,7 +27,7 @@ pub trait GlobalLockBackend { /// The backend used for this global lock. type Backend: Backend + 'static; /// The class for this global lock. - fn get_lock_class() -> &'static LockClassKey; + fn get_lock_class() -> Pin<&'static LockClassKey>; } /// Type used for global locks. @@ -270,7 +271,7 @@ impl $crate::sync::lock::GlobalLockBackend for $name { type Item = $valuety; type Backend = $crate::global_lock_inner!(backend $kind); - fn get_lock_class() -> &'static $crate::sync::LockClassKey { + fn get_lock_class() -> Pin<&'static $crate::sync::LockClassKey> { $crate::static_lock_class!() } } diff --git a/rust/kernel/sync/poll.rs b/rust/kernel/sync/poll.rs index d5f17153b424..c4934f82d68b 100644 --- a/rust/kernel/sync/poll.rs +++ b/rust/kernel/sync/poll.rs @@ -89,7 +89,7 @@ pub struct PollCondVar { impl PollCondVar { /// Constructs a new condvar initialiser. - pub fn new(name: &'static CStr, key: &'static LockClassKey) -> impl PinInit<Self> { + pub fn new(name: &'static CStr, key: Pin<&'static LockClassKey>) -> impl PinInit<Self> { pin_init!(Self { inner <- CondVar::new(name, key), }) diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs index 1dcd53478edd..f8f2f971f985 100644 --- a/rust/kernel/workqueue.rs +++ b/rust/kernel/workqueue.rs @@ -369,7 +369,8 @@ unsafe impl<T: ?Sized, const ID: u64> Sync for Work<T, ID> {} impl<T: ?Sized, const ID: u64> Work<T, ID> { /// Creates a new instance of [`Work`]. #[inline] - pub fn new(name: &'static CStr, key: &'static LockClassKey) -> impl PinInit<Self> + #[allow(clippy::new_ret_no_self)] + pub fn new(name: &'static CStr, key: Pin<&'static LockClassKey>) -> impl PinInit<Self> where T: WorkItem<ID>, { -- 2.34.1
