[PATCH v16 12/17] rust: sync: lock/global: Rename B to G in trait bounds

Lyude Paul posted 17 patches 3 days, 21 hours ago
[PATCH v16 12/17] rust: sync: lock/global: Rename B to G in trait bounds
Posted by Lyude Paul 3 days, 21 hours ago
Due to the introduction of Backend::BackendInContext, if we want to be able
support Lock types with a Context we need to be able to handle the fact
that the Backend for a returned Guard may not exactly match the Backend for
the lock. Before we add this though, rename B to G in all of our trait
bounds to make sure things don't become more difficult to understand once
we add a Backend bound.

There should be no functional changes in this patch.

Signed-off-by: Lyude Paul <lyude@redhat.com>
---
 rust/kernel/sync/atomic.rs      |  2 +-
 rust/kernel/sync/lock/global.rs | 58 ++++++++++++++++-----------------
 2 files changed, 30 insertions(+), 30 deletions(-)

diff --git a/rust/kernel/sync/atomic.rs b/rust/kernel/sync/atomic.rs
index 3afc376be42d9..c07a53f8360b4 100644
--- a/rust/kernel/sync/atomic.rs
+++ b/rust/kernel/sync/atomic.rs
@@ -21,8 +21,8 @@
 mod predefine;
 
 pub use internal::AtomicImpl;
-pub use ordering::{Acquire, Full, Relaxed, Release};
 pub(crate) use internal::{AtomicArithmeticOps, AtomicBasicOps, AtomicExchangeOps};
+pub use ordering::{Acquire, Full, Relaxed, Release};
 
 use crate::build_error;
 use internal::AtomicRepr;
diff --git a/rust/kernel/sync/lock/global.rs b/rust/kernel/sync/lock/global.rs
index 7030a47bc0ad1..06d62ad02f90d 100644
--- a/rust/kernel/sync/lock/global.rs
+++ b/rust/kernel/sync/lock/global.rs
@@ -33,18 +33,18 @@ pub trait GlobalLockBackend {
 /// Type used for global locks.
 ///
 /// See [`global_lock!`] for examples.
-pub struct GlobalLock<B: GlobalLockBackend> {
-    inner: Lock<B::Item, B::Backend>,
+pub struct GlobalLock<G: GlobalLockBackend> {
+    inner: Lock<G::Item, G::Backend>,
 }
 
-impl<B: GlobalLockBackend> GlobalLock<B> {
+impl<G: GlobalLockBackend> GlobalLock<G> {
     /// Creates a global lock.
     ///
     /// # Safety
     ///
     /// * Before any other method on this lock is called, [`Self::init`] must be called.
-    /// * The type `B` must not be used with any other lock.
-    pub const unsafe fn new(data: B::Item) -> Self {
+    /// * The type `G` must not be used with any other lock.
+    pub const unsafe fn new(data: G::Item) -> Self {
         Self {
             inner: Lock {
                 state: Opaque::uninit(),
@@ -68,23 +68,23 @@ pub unsafe fn init(&'static self) {
         // `init` before using any other methods. As `init` can only be called once, all other
         // uses of this lock must happen after this call.
         unsafe {
-            B::Backend::init(
+            G::Backend::init(
                 self.inner.state.get(),
-                B::NAME.as_char_ptr(),
-                B::get_lock_class().as_ptr(),
+                G::NAME.as_char_ptr(),
+                G::get_lock_class().as_ptr(),
             )
         }
     }
 
     /// Lock this global lock.
-    pub fn lock(&'static self) -> GlobalGuard<B> {
+    pub fn lock(&'static self) -> GlobalGuard<G> {
         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<G>> {
         Some(GlobalGuard {
             inner: self.inner.try_lock()?,
         })
@@ -94,21 +94,21 @@ 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<G: GlobalLockBackend> {
+    inner: Guard<'static, G::Item, G::Backend>,
 }
 
-impl<B: GlobalLockBackend> core::ops::Deref for GlobalGuard<B> {
-    type Target = B::Item;
+impl<G: GlobalLockBackend> core::ops::Deref for GlobalGuard<G> {
+    type Target = G::Item;
 
     fn deref(&self) -> &Self::Target {
         &self.inner
     }
 }
 
-impl<B: GlobalLockBackend> core::ops::DerefMut for GlobalGuard<B>
+impl<G: GlobalLockBackend> core::ops::DerefMut for GlobalGuard<G>
 where
-    B::Item: Unpin,
+    G::Item: Unpin,
 {
     fn deref_mut(&mut self) -> &mut Self::Target {
         &mut self.inner
@@ -118,33 +118,33 @@ fn deref_mut(&mut self) -> &mut Self::Target {
 /// A version of [`LockedBy`] for a [`GlobalLock`].
 ///
 /// See [`global_lock!`] for examples.
-pub struct GlobalLockedBy<T: ?Sized, B: GlobalLockBackend> {
-    _backend: PhantomData<B>,
+pub struct GlobalLockedBy<T: ?Sized, G: GlobalLockBackend> {
+    _backend: PhantomData<G>,
     value: UnsafeCell<T>,
 }
 
 // SAFETY: The same thread-safety rules as `LockedBy` apply to `GlobalLockedBy`.
-unsafe impl<T, B> Send for GlobalLockedBy<T, B>
+unsafe impl<T, G> Send for GlobalLockedBy<T, G>
 where
     T: ?Sized,
-    B: GlobalLockBackend,
-    LockedBy<T, B::Item>: Send,
+    G: GlobalLockBackend,
+    LockedBy<T, G::Item>: Send,
 {
 }
 
 // SAFETY: The same thread-safety rules as `LockedBy` apply to `GlobalLockedBy`.
-unsafe impl<T, B> Sync for GlobalLockedBy<T, B>
+unsafe impl<T, G> Sync for GlobalLockedBy<T, G>
 where
     T: ?Sized,
-    B: GlobalLockBackend,
-    LockedBy<T, B::Item>: Sync,
+    G: GlobalLockBackend,
+    LockedBy<T, G::Item>: Sync,
 {
 }
 
-impl<T, B: GlobalLockBackend> GlobalLockedBy<T, B> {
+impl<T, G: GlobalLockBackend> GlobalLockedBy<T, G> {
     /// Create a new [`GlobalLockedBy`].
     ///
-    /// The provided value will be protected by the global lock indicated by `B`.
+    /// The provided value will be protected by the global lock indicated by `G`.
     pub fn new(val: T) -> Self {
         Self {
             value: UnsafeCell::new(val),
@@ -153,11 +153,11 @@ pub fn new(val: T) -> Self {
     }
 }
 
-impl<T: ?Sized, B: GlobalLockBackend> GlobalLockedBy<T, B> {
+impl<T: ?Sized, G: GlobalLockBackend> GlobalLockedBy<T, G> {
     /// 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<G>) -> &'a T {
         // SAFETY: The lock is globally unique, so there can only be one guard.
         unsafe { &*self.value.get() }
     }
@@ -165,7 +165,7 @@ 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<G>) -> &'a mut T {
         // SAFETY: The lock is globally unique, so there can only be one guard.
         unsafe { &mut *self.value.get() }
     }
-- 
2.52.0
Re: [PATCH v16 12/17] rust: sync: lock/global: Rename B to G in trait bounds
Posted by Dirk Behme 2 days, 23 hours ago
On 15.12.25 18:57, Lyude Paul wrote:
> Due to the introduction of Backend::BackendInContext, if we want to be able
> support Lock types with a Context we need to be able to handle the fact
> that the Backend for a returned Guard may not exactly match the Backend for
> the lock. Before we add this though, rename B to G in all of our trait
> bounds to make sure things don't become more difficult to understand once
> we add a Backend bound.
> 
> There should be no functional changes in this patch.
> 
> Signed-off-by: Lyude Paul <lyude@redhat.com>
> ---
>  rust/kernel/sync/atomic.rs      |  2 +-
>  rust/kernel/sync/lock/global.rs | 58 ++++++++++++++++-----------------
>  2 files changed, 30 insertions(+), 30 deletions(-)
> 
> diff --git a/rust/kernel/sync/atomic.rs b/rust/kernel/sync/atomic.rs
> index 3afc376be42d9..c07a53f8360b4 100644
> --- a/rust/kernel/sync/atomic.rs
> +++ b/rust/kernel/sync/atomic.rs
> @@ -21,8 +21,8 @@
>  mod predefine;
>  
>  pub use internal::AtomicImpl;
> -pub use ordering::{Acquire, Full, Relaxed, Release};
>  pub(crate) use internal::{AtomicArithmeticOps, AtomicBasicOps, AtomicExchangeOps};
> +pub use ordering::{Acquire, Full, Relaxed, Release};

Just fyi, there is a (trivial) conflict of this with Miguel's recently
merged

commit 309e49039f124a ("rust: sync: atomic: separate import "blocks"")
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/rust/kernel/sync/atomic.rs?id=309e49039f124a9dcb99c05651af8eb8fa05bc29

If I haven't missed anything this is just to fix the alphabetical
order? So maybe this should go as an independent patch like Miguel's one?

Dirk
Re: [PATCH v16 12/17] rust: sync: lock/global: Rename B to G in trait bounds
Posted by Boqun Feng 1 day, 18 hours ago
On Tue, Dec 16, 2025 at 05:15:18PM +0100, Dirk Behme wrote:
> On 15.12.25 18:57, Lyude Paul wrote:
> > Due to the introduction of Backend::BackendInContext, if we want to be able
> > support Lock types with a Context we need to be able to handle the fact
> > that the Backend for a returned Guard may not exactly match the Backend for
> > the lock. Before we add this though, rename B to G in all of our trait
> > bounds to make sure things don't become more difficult to understand once
> > we add a Backend bound.
> > 
> > There should be no functional changes in this patch.
> > 
> > Signed-off-by: Lyude Paul <lyude@redhat.com>
> > ---
> >  rust/kernel/sync/atomic.rs      |  2 +-
> >  rust/kernel/sync/lock/global.rs | 58 ++++++++++++++++-----------------
> >  2 files changed, 30 insertions(+), 30 deletions(-)
> > 
> > diff --git a/rust/kernel/sync/atomic.rs b/rust/kernel/sync/atomic.rs
> > index 3afc376be42d9..c07a53f8360b4 100644
> > --- a/rust/kernel/sync/atomic.rs
> > +++ b/rust/kernel/sync/atomic.rs
> > @@ -21,8 +21,8 @@
> >  mod predefine;
> >  
> >  pub use internal::AtomicImpl;
> > -pub use ordering::{Acquire, Full, Relaxed, Release};
> >  pub(crate) use internal::{AtomicArithmeticOps, AtomicBasicOps, AtomicExchangeOps};
> > +pub use ordering::{Acquire, Full, Relaxed, Release};
> 
> Just fyi, there is a (trivial) conflict of this with Miguel's recently
> merged
> 

I think what Lyude has here is probably automatically added by rustfmt,
rebasing on v6.19-rc1 should avoid this.

Regards,
Boqun

> commit 309e49039f124a ("rust: sync: atomic: separate import "blocks"")
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/rust/kernel/sync/atomic.rs?id=309e49039f124a9dcb99c05651af8eb8fa05bc29
> 
> If I haven't missed anything this is just to fix the alphabetical
> order? So maybe this should go as an independent patch like Miguel's one?
> 
> Dirk