Originally, `Atomic::from_ptr()` requires `T` being a `Sync` because I
thought having the ability to do `from_ptr()` meant multiplle
`&Atomic<T>`s shared by different threads, which was identical (or
similar) to multiple `&T`s shared by different threads. Hence `T` was
required to be `Sync`. However this is not true, since `&Atomic<T>` is
not the same at `&T`. Moreover, having this bound makes `Atomic::<*mut
T>::from_ptr()` impossible, which is definitely not intended. Therefore
remove the `T: Sync` bound.

Fixes: 29c32c405e53 ("rust: sync: atomic: Add generic atomics")
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
---
 rust/kernel/sync/atomic.rs | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/rust/kernel/sync/atomic.rs b/rust/kernel/sync/atomic.rs
index 224bd57da1ab..d49ee45c6eb7 100644
--- a/rust/kernel/sync/atomic.rs
+++ b/rust/kernel/sync/atomic.rs
@@ -215,10 +215,7 @@ pub const fn new(v: T) -> Self {
     /// // no data race.
     /// unsafe { Atomic::from_ptr(foo_a_ptr) }.store(2, Release);
     /// ```
-    pub unsafe fn from_ptr<'a>(ptr: *mut T) -> &'a Self
-    where
-        T: Sync,
-    {
+    pub unsafe fn from_ptr<'a>(ptr: *mut T) -> &'a Self {
         // CAST: `T` and `Atomic<T>` have the same size, alignment and bit validity.
         // SAFETY: Per function safety requirement, `ptr` is a valid pointer and the object will
         // live long enough. It's safe to return a `&Atomic<T>` because function safety requirement
-- 
2.51.0

On Tue Jan 20, 2026 at 11:52 AM GMT, Boqun Feng wrote:
> Originally, `Atomic::from_ptr()` requires `T` being a `Sync` because I
> thought having the ability to do `from_ptr()` meant multiplle
> `&Atomic<T>`s shared by different threads, which was identical (or
> similar) to multiple `&T`s shared by different threads. Hence `T` was
> required to be `Sync`. However this is not true, since `&Atomic<T>` is
> not the same at `&T`. Moreover, having this bound makes `Atomic::<*mut
> T>::from_ptr()` impossible, which is definitely not intended. Therefore
> remove the `T: Sync` bound.
> 
> Fixes: 29c32c405e53 ("rust: sync: atomic: Add generic atomics")
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>

Title has "Atomci" instead of "Atomic"

Reviewed-by: Gary Guo <gary@garyguo.net>

> ---
>  rust/kernel/sync/atomic.rs | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)

On Tue, Jan 20, 2026 at 07:52:06PM +0800, Boqun Feng wrote:
> Originally, `Atomic::from_ptr()` requires `T` being a `Sync` because I
> thought having the ability to do `from_ptr()` meant multiplle
> `&Atomic<T>`s shared by different threads, which was identical (or
> similar) to multiple `&T`s shared by different threads. Hence `T` was
> required to be `Sync`. However this is not true, since `&Atomic<T>` is
> not the same at `&T`. Moreover, having this bound makes `Atomic::<*mut
> T>::from_ptr()` impossible, which is definitely not intended. Therefore
> remove the `T: Sync` bound.
> 
> Fixes: 29c32c405e53 ("rust: sync: atomic: Add generic atomics")
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>

Reviewed-by: Alice Ryhl <aliceryhl@google.com>

On Tue, Jan 20, 2026 at 07:52:06PM +0800, Boqun Feng wrote:
> Originally, `Atomic::from_ptr()` requires `T` being a `Sync` because I
> thought having the ability to do `from_ptr()` meant multiplle
> `&Atomic<T>`s shared by different threads, which was identical (or
> similar) to multiple `&T`s shared by different threads. Hence `T` was
> required to be `Sync`. However this is not true, since `&Atomic<T>` is
> not the same at `&T`. Moreover, having this bound makes `Atomic::<*mut
> T>::from_ptr()` impossible, which is definitely not intended. Therefore
> remove the `T: Sync` bound.
> 
> Fixes: 29c32c405e53 ("rust: sync: atomic: Add generic atomics")
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>

there is a typo in patch title