[PATCH v3 2/3] rust: sync: Introduce lock::Backend::Context
From: Lyude Paul <lyude@redhat.com>
Date: 2024-08-02 00:15:30
Also in:
lkml
Subsystem:
locking primitives, rust, the rest · Maintainers:
Peter Zijlstra, Ingo Molnar, Will Deacon, Boqun Feng, Miguel Ojeda, Linus Torvalds
Now that we've introduced an `IrqDisabled` token for marking contexts in which IRQs are disabled, we need a way to be able to pass it to locks that require that IRQs are disabled. In order to continue using the `lock::Backend` type instead of inventing our own thing, we accomplish this by adding the associated Context type, along with a `lock_with()` function that can accept a Context when acquiring a lock. To allow current users of context-less locks to keep using the normal `lock()` method, we take an example from Wedson Almeida Filho's work and add a `where T<'a>: Default` bound to `lock()` so that it can only be called on lock types where the context is simply a placeholder value, then re-implement it through the new `lock_with()` function. Signed-off-by: Lyude Paul <lyude@redhat.com> --- V3: * Use explicit lifetimes in lock_with() to ensure self and _context have the same lifetime (Benno) * Use () for locks that don't need a Context instead of PhantomData (Benno) --- rust/kernel/sync/lock.rs | 17 +++++++++++++++-- rust/kernel/sync/lock/mutex.rs | 1 + rust/kernel/sync/lock/spinlock.rs | 1 + 3 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
index f6c34ca4d819f..0c72677233946 100644
--- a/rust/kernel/sync/lock.rs
+++ b/rust/kernel/sync/lock.rs@@ -38,6 +38,9 @@ pub unsafe trait Backend { /// [`unlock`]: Backend::unlock type GuardState; + /// The context which much be provided to acquire the lock. + type Context<'a>; + /// Initialises the lock. /// /// # Safety
@@ -120,14 +123,24 @@ pub fn new(t: T, name: &'static CStr, key: &'static LockClassKey) -> impl PinIni } impl<T: ?Sized, B: Backend> Lock<T, B> { - /// Acquires the lock and gives the caller access to the data protected by it. - pub fn lock(&self) -> Guard<'_, T, B> { + /// Acquires the lock with the given context and gives the caller access to the data protected + /// by it. + pub fn lock_with<'a>(&'a self, _context: B::Context<'a>) -> Guard<'a, T, B> { // SAFETY: The constructor of the type calls `init`, so the existence of the object proves // that `init` was called. let state = unsafe { B::lock(self.state.get()) }; // SAFETY: The lock was just acquired. unsafe { Guard::new(self, state) } } + + /// Acquires the lock and gives the caller access to the data protected by it. + #[inline] + pub fn lock<'a>(&'a self) -> Guard<'a, T, B> + where + B::Context<'a>: Default, + { + self.lock_with(B::Context::default()) + } } /// A lock guard.
diff --git a/rust/kernel/sync/lock/mutex.rs b/rust/kernel/sync/lock/mutex.rs
index 30632070ee670..7c2c239944931 100644
--- a/rust/kernel/sync/lock/mutex.rs
+++ b/rust/kernel/sync/lock/mutex.rs@@ -93,6 +93,7 @@ macro_rules! new_mutex { unsafe impl super::Backend for MutexBackend { type State = bindings::mutex; type GuardState = (); + type Context<'a> = (); unsafe fn init( ptr: *mut Self::State,
diff --git a/rust/kernel/sync/lock/spinlock.rs b/rust/kernel/sync/lock/spinlock.rs
index ea5c5bc1ce12e..97d85a5576615 100644
--- a/rust/kernel/sync/lock/spinlock.rs
+++ b/rust/kernel/sync/lock/spinlock.rs@@ -92,6 +92,7 @@ macro_rules! new_spinlock { unsafe impl super::Backend for SpinLockBackend { type State = bindings::spinlock_t; type GuardState = (); + type Context<'a> = (); unsafe fn init( ptr: *mut Self::State,
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2.45.2