rust: sync: Inline various lock related methods

While debugging a different issue [1], the following relocation was
noticed in the rust_binder.ko file:

	R_AARCH64_CALL26	_RNvXNtNtNtCsdfZWD8DztAw_6kernel4sync4lock8spinlockNtB2_15SpinLockBackendNtB4_7Backend6unlock

This relocation (and a similar one for lock) occurred many times
throughout the module. That is not really useful because all this
function does is call spin_unlock(), so what we actually want here is
that a call to spin_unlock() dirctly is generated in favor of this
wrapper method.

Thus, mark these methods inline.

[boqun: Reword the commit message a bit]

Link: https://lore.kernel.org/p/20251111-binder-fix-list-remove-v1-0-8ed14a0da63d@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20251218-inline-lock-unlock-v2-1-fbadac8bd61b@google.com

rust/kernel/sync/lock.rs

@@ -156,6 +156,7 @@ impl<B: Backend> Lock<(), B> {
     /// the whole lifetime of `'a`.
     ///
     /// [`State`]: Backend::State
+    #[inline]
     pub unsafe fn from_raw<'a>(ptr: *mut B::State) -> &'a Self {
         // SAFETY:
         // - By the safety contract `ptr` must point to a valid initialised instance of `B::State`
@@ -169,6 +170,7 @@ impl<B: Backend> Lock<(), B> {
 
 impl<T: ?Sized, B: Backend> Lock<T, B> {
     /// Acquires the lock and gives the caller access to the data protected by it.
+    #[inline]
     pub fn lock(&self) -> Guard<'_, T, B> {
         // SAFETY: The constructor of the type calls `init`, so the existence of the object proves
         // that `init` was called.
@@ -182,6 +184,7 @@ impl<T: ?Sized, B: Backend> Lock<T, B> {
     /// Returns a guard that can be used to access the data protected by the lock if successful.
     // `Option<T>` is not `#[must_use]` even if `T` is, thus the attribute is needed here.
     #[must_use = "if unused, the lock will be immediately unlocked"]
+    #[inline]
     pub fn try_lock(&self) -> Option<Guard<'_, T, B>> {
         // SAFETY: The constructor of the type calls `init`, so the existence of the object proves
         // that `init` was called.
@@ -275,6 +278,7 @@ impl<'a, T: ?Sized, B: Backend> Guard<'a, T, B> {
 impl<T: ?Sized, B: Backend> core::ops::Deref for Guard<'_, T, B> {
     type Target = T;
 
+    #[inline]
     fn deref(&self) -> &Self::Target {
         // SAFETY: The caller owns the lock, so it is safe to deref the protected data.
         unsafe { &*self.lock.data.get() }
@@ -285,6 +289,7 @@ impl<T: ?Sized, B: Backend> core::ops::DerefMut for Guard<'_, T, B>
 where
     T: Unpin,
 {
+    #[inline]
     fn deref_mut(&mut self) -> &mut Self::Target {
         // SAFETY: The caller owns the lock, so it is safe to deref the protected data.
         unsafe { &mut *self.lock.data.get() }
@@ -292,6 +297,7 @@ where
 }
 
 impl<T: ?Sized, B: Backend> Drop for Guard<'_, T, B> {
+    #[inline]
     fn drop(&mut self) {
         // SAFETY: The caller owns the lock, so it is safe to unlock it.
         unsafe { B::unlock(self.lock.state.get(), &self.state) };
@@ -304,6 +310,7 @@ impl<'a, T: ?Sized, B: Backend> Guard<'a, T, B> {
     /// # Safety
     ///
     /// The caller must ensure that it owns the lock.
+    #[inline]
     pub unsafe fn new(lock: &'a Lock<T, B>, state: B::GuardState) -> Self {
         // SAFETY: The caller can only hold the lock if `Backend::init` has already been called.
         unsafe { B::assert_is_held(lock.state.get()) };

rust/kernel/sync/lock/global.rs

@@ -77,6 +77,7 @@ impl<B: GlobalLockBackend> GlobalLock<B> {
     }
 
     /// Lock this global lock.
+    #[inline]
     pub fn lock(&'static self) -> GlobalGuard<B> {
         GlobalGuard {
             inner: self.inner.lock(),
@@ -84,6 +85,7 @@ impl<B: GlobalLockBackend> GlobalLock<B> {
     }
 
     /// Try to lock this global lock.
+    #[inline]
     pub fn try_lock(&'static self) -> Option<GlobalGuard<B>> {
         Some(GlobalGuard {
             inner: self.inner.try_lock()?,

rust/kernel/sync/lock/mutex.rs

@@ -102,6 +102,7 @@ unsafe impl super::Backend for MutexBackend {
     type State = bindings::mutex;
     type GuardState = ();
 
+    #[inline]
     unsafe fn init(
         ptr: *mut Self::State,
         name: *const crate::ffi::c_char,
@@ -112,18 +113,21 @@ unsafe impl super::Backend for MutexBackend {
         unsafe { bindings::__mutex_init(ptr, name, key) }
     }
 
+    #[inline]
     unsafe fn lock(ptr: *mut Self::State) -> Self::GuardState {
         // SAFETY: The safety requirements of this function ensure that `ptr` points to valid
         // memory, and that it has been initialised before.
         unsafe { bindings::mutex_lock(ptr) };
     }
 
+    #[inline]
     unsafe fn unlock(ptr: *mut Self::State, _guard_state: &Self::GuardState) {
         // SAFETY: The safety requirements of this function ensure that `ptr` is valid and that the
         // caller is the owner of the mutex.
         unsafe { bindings::mutex_unlock(ptr) };
     }
 
+    #[inline]
     unsafe fn try_lock(ptr: *mut Self::State) -> Option<Self::GuardState> {
         // SAFETY: The `ptr` pointer is guaranteed to be valid and initialized before use.
         let result = unsafe { bindings::mutex_trylock(ptr) };
@@ -135,6 +139,7 @@ unsafe impl super::Backend for MutexBackend {
         }
     }
 
+    #[inline]
     unsafe fn assert_is_held(ptr: *mut Self::State) {
         // SAFETY: The `ptr` pointer is guaranteed to be valid and initialized before use.
         unsafe { bindings::mutex_assert_is_held(ptr) }

rust/kernel/sync/lock/spinlock.rs

@@ -101,6 +101,7 @@ unsafe impl super::Backend for SpinLockBackend {
     type State = bindings::spinlock_t;
     type GuardState = ();
 
+    #[inline]
     unsafe fn init(
         ptr: *mut Self::State,
         name: *const crate::ffi::c_char,
@@ -111,18 +112,21 @@ unsafe impl super::Backend for SpinLockBackend {
         unsafe { bindings::__spin_lock_init(ptr, name, key) }
     }
 
+    #[inline]
     unsafe fn lock(ptr: *mut Self::State) -> Self::GuardState {
         // SAFETY: The safety requirements of this function ensure that `ptr` points to valid
         // memory, and that it has been initialised before.
         unsafe { bindings::spin_lock(ptr) }
     }
 
+    #[inline]
     unsafe fn unlock(ptr: *mut Self::State, _guard_state: &Self::GuardState) {
         // SAFETY: The safety requirements of this function ensure that `ptr` is valid and that the
         // caller is the owner of the spinlock.
         unsafe { bindings::spin_unlock(ptr) }
     }
 
+    #[inline]
     unsafe fn try_lock(ptr: *mut Self::State) -> Option<Self::GuardState> {
         // SAFETY: The `ptr` pointer is guaranteed to be valid and initialized before use.
         let result = unsafe { bindings::spin_trylock(ptr) };
@@ -134,6 +138,7 @@ unsafe impl super::Backend for SpinLockBackend {
         }
     }
 
+    #[inline]
     unsafe fn assert_is_held(ptr: *mut Self::State) {
         // SAFETY: The `ptr` pointer is guaranteed to be valid and initialized before use.
         unsafe { bindings::spin_assert_is_held(ptr) }