From: Alice Ryhl <aliceryhl@xxxxxxxxxx>
When working with a bus device, many operations are only possible while
the device is still bound. The &Device<Bound> type represents a proof in
the type system that you are in a scope where the device is guaranteed
to still be bound. Since we deregister irq callbacks when unbinding a
device, if an irq callback is running, that implies that the device has
not yet been unbound.
To allow drivers to take advantage of that, add an additional argument
to irq callbacks.
Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
---
rust/kernel/irq/request.rs | 95 +++++++++++++++++++++++++++-------------------
1 file changed, 57 insertions(+), 38 deletions(-)
diff --git a/rust/kernel/irq/request.rs b/rust/kernel/irq/request.rs
index 4033df7d0dce1dbc9cc9b0b0f32fb9f8aa285d6b..b150563fdef809899c7ca39221c4928238e31110 100644
--- a/rust/kernel/irq/request.rs
+++ b/rust/kernel/irq/request.rs
@@ -36,18 +36,18 @@ pub trait Handler: Sync {
/// All work that does not necessarily need to be executed from
/// interrupt context, should be deferred to a threaded handler.
/// See also [`ThreadedRegistration`].
- fn handle(&self) -> IrqReturn;
+ fn handle(&self, device: &Device<Bound>) -> IrqReturn;
}
impl<T: ?Sized + Handler + Send> Handler for Arc<T> {
- fn handle(&self) -> IrqReturn {
- T::handle(self)
+ fn handle(&self, device: &Device<Bound>) -> IrqReturn {
+ T::handle(self, device)
}
}
impl<T: ?Sized + Handler, A: Allocator> Handler for Box<T, A> {
- fn handle(&self) -> IrqReturn {
- T::handle(self)
+ fn handle(&self, device: &Device<Bound>) -> IrqReturn {
+ T::handle(self, device)
}
}
@@ -140,7 +140,7 @@ pub fn irq(&self) -> u32 {
///
/// ```
/// use kernel::c_str;
-/// use kernel::device::Bound;
+/// use kernel::device::{Bound, Device};
/// use kernel::irq::{self, Flags, IrqRequest, IrqReturn, Registration};
/// use kernel::prelude::*;
/// use kernel::sync::{Arc, Completion};
@@ -154,7 +154,7 @@ pub fn irq(&self) -> u32 {
///
/// impl irq::Handler for Data {
/// // Executed in IRQ context.
-/// fn handle(&self) -> IrqReturn {
+/// fn handle(&self, _dev: &Device<Bound>) -> IrqReturn {
/// self.completion.complete_all();
/// IrqReturn::Handled
/// }
@@ -180,7 +180,7 @@ pub fn irq(&self) -> u32 {
///
/// # Invariants
///
-/// * We own an irq handler using `&self.handler` as its private data.
+/// * We own an irq handler whose cookie is a pointer to `Self`.
#[pin_data]
pub struct Registration<T: Handler + 'static> {
#[pin]
@@ -208,21 +208,24 @@ pub fn new<'a>(
inner <- Devres::new(
request.dev,
try_pin_init!(RegistrationInner {
- // SAFETY: `this` is a valid pointer to the `Registration` instance
- cookie: unsafe { &raw mut (*this.as_ptr()).handler }.cast(),
+ // INVARIANT: `this` is a valid pointer to the `Registration` instance
+ cookie: this.as_ptr().cast::<c_void>(),
irq: {
// SAFETY:
// - The callbacks are valid for use with request_irq.
// - If this succeeds, the slot is guaranteed to be valid until the
// destructor of Self runs, which will deregister the callbacks
// before the memory location becomes invalid.
+ // - When request_irq is called, everything that handle_irq_callback will
+ // touch has already been initialized, so it's safe for the callback to
+ // be called immediately.
to_result(unsafe {
bindings::request_irq(
request.irq,
Some(handle_irq_callback::<T>),
flags.into_inner(),
name.as_char_ptr(),
- (&raw mut (*this.as_ptr()).handler).cast(),
+ this.as_ptr().cast::<c_void>(),
)
})?;
request.irq
@@ -259,9 +262,13 @@ pub fn synchronize(&self, dev: &Device<Bound>) -> Result {
///
/// This function should be only used as the callback in `request_irq`.
unsafe extern "C" fn handle_irq_callback<T: Handler>(_irq: i32, ptr: *mut c_void) -> c_uint {
- // SAFETY: `ptr` is a pointer to T set in `Registration::new`
- let handler = unsafe { &*(ptr as *const T) };
- T::handle(handler) as c_uint
+ // SAFETY: `ptr` is a pointer to `Registration<T>` set in `Registration::new`
+ let registration = unsafe { &*(ptr as *const Registration<T>) };
+ // SAFETY: The irq callback is removed before the device is unbound, so the fact that the irq
+ // callback is running implies that the device has not yet been unbound.
+ let device = unsafe { registration.inner.device().as_bound() };
+
+ T::handle(®istration.handler, device) as c_uint
}
/// The value that can be returned from [`ThreadedHandler::handle`].
@@ -287,7 +294,8 @@ pub trait ThreadedHandler: Sync {
/// handler, i.e. [`ThreadedHandler::handle_threaded`].
///
/// The default implementation returns [`ThreadedIrqReturn::WakeThread`].
- fn handle(&self) -> ThreadedIrqReturn {
+ #[expect(unused_variables)]
+ fn handle(&self, device: &Device<Bound>) -> ThreadedIrqReturn {
ThreadedIrqReturn::WakeThread
}
@@ -295,26 +303,26 @@ fn handle(&self) -> ThreadedIrqReturn {
///
/// This is executed in process context. The kernel creates a dedicated
/// `kthread` for this purpose.
- fn handle_threaded(&self) -> IrqReturn;
+ fn handle_threaded(&self, device: &Device<Bound>) -> IrqReturn;
}
impl<T: ?Sized + ThreadedHandler + Send> ThreadedHandler for Arc<T> {
- fn handle(&self) -> ThreadedIrqReturn {
- T::handle(self)
+ fn handle(&self, device: &Device<Bound>) -> ThreadedIrqReturn {
+ T::handle(self, device)
}
- fn handle_threaded(&self) -> IrqReturn {
- T::handle_threaded(self)
+ fn handle_threaded(&self, device: &Device<Bound>) -> IrqReturn {
+ T::handle_threaded(self, device)
}
}
impl<T: ?Sized + ThreadedHandler, A: Allocator> ThreadedHandler for Box<T, A> {
- fn handle(&self) -> ThreadedIrqReturn {
- T::handle(self)
+ fn handle(&self, device: &Device<Bound>) -> ThreadedIrqReturn {
+ T::handle(self, device)
}
- fn handle_threaded(&self) -> IrqReturn {
- T::handle_threaded(self)
+ fn handle_threaded(&self, device: &Device<Bound>) -> IrqReturn {
+ T::handle_threaded(self, device)
}
}
@@ -333,7 +341,7 @@ fn handle_threaded(&self) -> IrqReturn {
///
/// ```
/// use kernel::c_str;
-/// use kernel::device::Bound;
+/// use kernel::device::{Bound, Device};
/// use kernel::irq::{
/// self, Flags, IrqRequest, IrqReturn, ThreadedHandler, ThreadedIrqReturn,
/// ThreadedRegistration,
@@ -357,7 +365,7 @@ fn handle_threaded(&self) -> IrqReturn {
/// // This will run (in a separate kthread) if and only if
/// // [`ThreadedHandler::handle`] returns [`WakeThread`], which it does by
/// // default.
-/// fn handle_threaded(&self) -> IrqReturn {
+/// fn handle_threaded(&self, _dev: &Device<Bound>) -> IrqReturn {
/// let mut data = self.value.lock();
/// *data += 1;
/// IrqReturn::Handled
@@ -390,7 +398,7 @@ fn handle_threaded(&self) -> IrqReturn {
///
/// # Invariants
///
-/// * We own an irq handler using `&T` as its private data.
+/// * We own an irq handler whose cookie is a pointer to `Self`.
#[pin_data]
pub struct ThreadedRegistration<T: ThreadedHandler + 'static> {
#[pin]
@@ -418,14 +426,17 @@ pub fn new<'a>(
inner <- Devres::new(
request.dev,
try_pin_init!(RegistrationInner {
- // SAFETY: `this` is a valid pointer to the `ThreadedRegistration` instance.
- cookie: unsafe { &raw mut (*this.as_ptr()).handler }.cast(),
+ // INVARIANT: `this` is a valid pointer to the `ThreadedRegistration` instance.
+ cookie: this.as_ptr().cast::<c_void>(),
irq: {
// SAFETY:
// - The callbacks are valid for use with request_threaded_irq.
// - If this succeeds, the slot is guaranteed to be valid until the
- // destructor of Self runs, which will deregister the callbacks
- // before the memory location becomes invalid.
+ // destructor of Self runs, which will deregister the callbacks
+ // before the memory location becomes invalid.
+ // - When request_threaded_irq is called, everything that the two callbacks
+ // will touch has already been initialized, so it's safe for the
+ // callbacks to be called immediately.
to_result(unsafe {
bindings::request_threaded_irq(
request.irq,
@@ -433,7 +444,7 @@ pub fn new<'a>(
Some(thread_fn_callback::<T>),
flags.into_inner(),
name.as_char_ptr(),
- (&raw mut (*this.as_ptr()).handler).cast(),
+ this.as_ptr().cast::<c_void>(),
)
})?;
request.irq
@@ -473,16 +484,24 @@ pub fn synchronize(&self, dev: &Device<Bound>) -> Result {
_irq: i32,
ptr: *mut c_void,
) -> c_uint {
- // SAFETY: `ptr` is a pointer to T set in `ThreadedRegistration::new`
- let handler = unsafe { &*(ptr as *const T) };
- T::handle(handler) as c_uint
+ // SAFETY: `ptr` is a pointer to `ThreadedRegistration<T>` set in `ThreadedRegistration::new`
+ let registration = unsafe { &*(ptr as *const ThreadedRegistration<T>) };
+ // SAFETY: The irq callback is removed before the device is unbound, so the fact that the irq
+ // callback is running implies that the device has not yet been unbound.
+ let device = unsafe { registration.inner.device().as_bound() };
+
+ T::handle(®istration.handler, device) as c_uint
}
/// # Safety
///
/// This function should be only used as the callback in `request_threaded_irq`.
unsafe extern "C" fn thread_fn_callback<T: ThreadedHandler>(_irq: i32, ptr: *mut c_void) -> c_uint {
- // SAFETY: `ptr` is a pointer to T set in `ThreadedRegistration::new`
- let handler = unsafe { &*(ptr as *const T) };
- T::handle_threaded(handler) as c_uint
+ // SAFETY: `ptr` is a pointer to `ThreadedRegistration<T>` set in `ThreadedRegistration::new`
+ let registration = unsafe { &*(ptr as *const ThreadedRegistration<T>) };
+ // SAFETY: The irq callback is removed before the device is unbound, so the fact that the irq
+ // callback is running implies that the device has not yet been unbound.
+ let device = unsafe { registration.inner.device().as_bound() };
+
+ T::handle_threaded(®istration.handler, device) as c_uint
}
--
2.50.1
