3 files changed, 36 insertions, 8 deletions
diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
index f6c34ca4d819..d6e9bab114b8 100644
--- a/rust/kernel/sync/lock.rs
+++ b/rust/kernel/sync/lock.rs
@@ -6,8 +6,13 @@
 //! spinlocks, raw spinlocks) to be provided with minimal effort.
 
 use super::LockClassKey;
-use crate::{init::PinInit, pin_init, str::CStr, types::Opaque, types::ScopeGuard};
-use core::{cell::UnsafeCell, marker::PhantomData, marker::PhantomPinned};
+use crate::{
+    init::PinInit,
+    pin_init,
+    str::CStr,
+    types::{NotThreadSafe, Opaque, ScopeGuard},
+};
+use core::{cell::UnsafeCell, marker::PhantomPinned};
 use macros::pin_data;
 
 pub mod mutex;
@@ -139,7 +144,7 @@ impl<T: ?Sized, B: Backend> Lock<T, B> {
 pub struct Guard<'a, T: ?Sized, B: Backend> {
     pub(crate) lock: &'a Lock<T, B>,
     pub(crate) state: B::GuardState,
-    _not_send: PhantomData<*mut ()>,
+    _not_send: NotThreadSafe,
 }
 
 // SAFETY: `Guard` is sync when the data protected by the lock is also sync.
@@ -191,7 +196,7 @@ impl<'a, T: ?Sized, B: Backend> Guard<'a, T, B> {
         Self {
             lock,
             state,
-            _not_send: PhantomData,
+            _not_send: NotThreadSafe,
         }
     }
 }
diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs
index 55dff7e088bf..278c623de0c6 100644
--- a/rust/kernel/task.rs
+++ b/rust/kernel/task.rs
@@ -4,10 +4,12 @@
 //!
 //! C header: [`include/linux/sched.h`](srctree/include/linux/sched.h).
 
-use crate::types::Opaque;
+use crate::{
+    bindings,
+    types::{NotThreadSafe, Opaque},
+};
 use core::{
     ffi::{c_int, c_long, c_uint},
-    marker::PhantomData,
     ops::Deref,
     ptr,
 };
@@ -106,7 +108,7 @@ impl Task {
     pub unsafe fn current() -> impl Deref<Target = Task> {
         struct TaskRef<'a> {
             task: &'a Task,
-            _not_send: PhantomData<*mut ()>,
+            _not_send: NotThreadSafe,
         }
 
         impl Deref for TaskRef<'_> {
@@ -125,7 +127,7 @@ impl Task {
             // that `TaskRef` is not `Send`, we know it cannot be transferred to another thread
             // (where it could potentially outlive the caller).
             task: unsafe { &*ptr.cast() },
-            _not_send: PhantomData,
+            _not_send: NotThreadSafe,
         }
     }
 
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index 9e7ca066355c..3238ffaab031 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -532,3 +532,24 @@ unsafe impl AsBytes for str {}
 // does not have any uninitialized portions either.
 unsafe impl<T: AsBytes> AsBytes for [T] {}
 unsafe impl<T: AsBytes, const N: usize> AsBytes for [T; N] {}
+
+/// Zero-sized type to mark types not [`Send`].
+///
+/// Add this type as a field to your struct if your type should not be sent to a different task.
+/// Since [`Send`] is an auto trait, adding a single field that is `!Send` will ensure that the
+/// whole type is `!Send`.
+///
+/// If a type is `!Send` it is impossible to give control over an instance of the type to another
+/// task. This is useful to include in types that store or reference task-local information. A file
+/// descriptor is an example of such task-local information.
+///
+/// This type also makes the type `!Sync`, which prevents immutable access to the value from
+/// several threads in parallel.
+pub type NotThreadSafe = PhantomData<*mut ()>;
+
+/// Used to construct instances of type [`NotThreadSafe`] similar to how `PhantomData` is
+/// constructed.
+///
+/// [`NotThreadSafe`]: type@NotThreadSafe
+#[allow(non_upper_case_globals)]
+pub const NotThreadSafe: NotThreadSafe = PhantomData;