linux-kernel - [RFC RESEND v10 09/14] rust: sync: Add a lifetime parameter to lock::global::GlobalGuard

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Message-ID: <20250527222254.565881-10-lyude@redhat.com>
Date: Tue, 27 May 2025 18:21:50 -0400
From: Lyude Paul <lyude@...hat.com>
To: rust-for-linux@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Boqun Feng <boqun.feng@...il.com>,
	linux-kernel@...r.kernel.org,
	Daniel Almeida <daniel.almeida@...labora.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Will Deacon <will@...nel.org>,
	Waiman Long <longman@...hat.com>,
	Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <lossin@...nel.org>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Trevor Gross <tmgross@...ch.edu>,
	Danilo Krummrich <dakr@...nel.org>
Subject: [RFC RESEND v10 09/14] rust: sync: Add a lifetime parameter to lock::global::GlobalGuard

While a GlobalLock is always going to be static, in the case of locks with
explicit backend contexts the GlobalGuard will not be 'static and will
instead share the lifetime of the context. So, add a lifetime parameter to
GlobalGuard to allow for this so we can implement GlobalGuard support for
SpinlockIrq.

Signed-off-by: Lyude Paul <lyude@...hat.com>
---
 rust/kernel/sync/lock/global.rs | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/rust/kernel/sync/lock/global.rs b/rust/kernel/sync/lock/global.rs
index 47e200b750c1d..45400824b0940 100644
--- a/rust/kernel/sync/lock/global.rs
+++ b/rust/kernel/sync/lock/global.rs
@@ -37,7 +37,7 @@ pub struct GlobalLock<B: GlobalLockBackend> {
     inner: Lock<B::Item, B::Backend>,
 }
 
-impl<B: GlobalLockBackend> GlobalLock<B> {
+impl<'a, B: GlobalLockBackend> GlobalLock<B> {
     /// Creates a global lock.
     ///
     /// # Safety
@@ -77,14 +77,14 @@ pub unsafe fn init(&'static self) {
     }
 
     /// Lock this global lock.
-    pub fn lock(&'static self) -> GlobalGuard<B> {
+    pub fn lock(&'static self) -> GlobalGuard<'static, B> {
         GlobalGuard {
             inner: self.inner.lock(),
         }
     }
 
     /// Try to lock this global lock.
-    pub fn try_lock(&'static self) -> Option<GlobalGuard<B>> {
+    pub fn try_lock(&'static self) -> Option<GlobalGuard<'static, B>> {
         Some(GlobalGuard {
             inner: self.inner.try_lock()?,
         })
@@ -94,11 +94,11 @@ pub fn try_lock(&'static self) -> Option<GlobalGuard<B>> {
 /// A guard for a [`GlobalLock`].
 ///
 /// See [`global_lock!`] for examples.
-pub struct GlobalGuard<B: GlobalLockBackend> {
-    inner: Guard<'static, B::Item, B::Backend>,
+pub struct GlobalGuard<'a, B: GlobalLockBackend> {
+    inner: Guard<'a, B::Item, B::Backend>,
 }
 
-impl<B: GlobalLockBackend> core::ops::Deref for GlobalGuard<B> {
+impl<'a, B: GlobalLockBackend> core::ops::Deref for GlobalGuard<'a, B> {
     type Target = B::Item;
 
     fn deref(&self) -> &Self::Target {
@@ -106,7 +106,7 @@ fn deref(&self) -> &Self::Target {
     }
 }
 
-impl<B: GlobalLockBackend> core::ops::DerefMut for GlobalGuard<B> {
+impl<'a, B: GlobalLockBackend> core::ops::DerefMut for GlobalGuard<'a, B> {
     fn deref_mut(&mut self) -> &mut Self::Target {
         &mut self.inner
     }
@@ -154,7 +154,7 @@ impl<T: ?Sized, B: GlobalLockBackend> GlobalLockedBy<T, B> {
     /// Access the value immutably.
     ///
     /// The caller must prove shared access to the lock.
-    pub fn as_ref<'a>(&'a self, _guard: &'a GlobalGuard<B>) -> &'a T {
+    pub fn as_ref<'a>(&'a self, _guard: &'a GlobalGuard<'_, B>) -> &'a T {
         // SAFETY: The lock is globally unique, so there can only be one guard.
         unsafe { &*self.value.get() }
     }
@@ -162,7 +162,7 @@ pub fn as_ref<'a>(&'a self, _guard: &'a GlobalGuard<B>) -> &'a T {
     /// Access the value mutably.
     ///
     /// The caller must prove shared exclusive to the lock.
-    pub fn as_mut<'a>(&'a self, _guard: &'a mut GlobalGuard<B>) -> &'a mut T {
+    pub fn as_mut<'a>(&'a self, _guard: &'a mut GlobalGuard<'_, B>) -> &'a mut T {
         // SAFETY: The lock is globally unique, so there can only be one guard.
         unsafe { &mut *self.value.get() }
     }
@@ -232,7 +232,7 @@ pub fn get_mut(&mut self) -> &mut T {
 ///     /// Increment the counter in this instance.
 ///     ///
 ///     /// The caller must hold the `MY_MUTEX` mutex.
-///     fn increment(&self, guard: &mut GlobalGuard<MY_MUTEX>) -> u32 {
+///     fn increment(&self, guard: &mut GlobalGuard<'_, MY_MUTEX>) -> u32 {
 ///         let my_counter = self.my_counter.as_mut(guard);
 ///         *my_counter += 1;
 ///         *my_counter
-- 
2.49.0