rust: irq: add `'static` bounds to irq callbacks

These callback functions take a generic `T` that is used in the body as
the generic argument in `Registration` and `ThreadedRegistration`. Those
types require `T: 'static`, but due to a compiler bug this requirement
isn't propagated to the function. Thus add the bound. This was caught in
the upstream Rust CI [1].

[ The three errors looked similar and will start appearing with Rust
  1.95.0 (expected 2026-04-16). The first one was:

      error[E0310]: the parameter type `T` may not live long enough
      Error:    --> rust/kernel/irq/request.rs:266:43
          |
      266 |     let registration = unsafe { &*(ptr as *const Registration<T>) };
          |                                           ^^^^^^^^^^^^^^^^^^^^^^
          |                                           |
          |                                           the parameter type `T` must be valid for the static lifetime...
          |                                           ...so that the type `T` will meet its required lifetime bounds
          |
      help: consider adding an explicit lifetime bound
          |
      264 | unsafe extern "C" fn handle_irq_callback<T: Handler + 'static>(_irq: i32, ptr: *mut c_void) -> c_uint {
          |                                                     +++++++++

    - Miguel ]

Link: https://github.com/rust-lang/rust/pull/149389 [1]
Signed-off-by: Benno Lossin <lossin@kernel.org>
Cc: stable@vger.kernel.org
Fixes: 29e16fcd67ee ("rust: irq: add &Device<Bound> argument to irq callbacks")
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/rust-for-linux/20260217222425.8755-1-cole@unwrap.rs/
Link: https://patch.msgid.link/20260214092740.3201946-1-lossin@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 9 insertions, 3 deletions

diff --git a/rust/kernel/irq/request.rs b/rust/kernel/irq/request.rs
index b150563fdef8..2ceeaeb0543a 100644
--- a/rust/kernel/irq/request.rs
+++ b/rust/kernel/irq/request.rs
@@ -261,7 +261,10 @@ impl<T: Handler + 'static> Registration<T> {
 /// # Safety
 ///
 /// 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 {
+unsafe extern "C" fn handle_irq_callback<T: Handler + 'static>(
+    _irq: i32,
+    ptr: *mut c_void,
+) -> 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
@@ -480,7 +483,7 @@ impl<T: ThreadedHandler + 'static> ThreadedRegistration<T> {
 /// # Safety
 ///
 /// This function should be only used as the callback in `request_threaded_irq`.
-unsafe extern "C" fn handle_threaded_irq_callback<T: ThreadedHandler>(
+unsafe extern "C" fn handle_threaded_irq_callback<T: ThreadedHandler + 'static>(
     _irq: i32,
     ptr: *mut c_void,
 ) -> c_uint {
@@ -496,7 +499,10 @@ unsafe extern "C" fn handle_threaded_irq_callback<T: ThreadedHandler>(
 /// # 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 {
+unsafe extern "C" fn thread_fn_callback<T: ThreadedHandler + 'static>(
+    _irq: i32,
+    ptr: *mut c_void,
+) -> 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