From e0bda4677cd02dce219de937e36b193796bf4a51 Mon Sep 17 00:00:00 2001
From: Ruihan Li <lrh2000@pku.edu.cn>
Date: Fri, 11 Apr 2025 16:25:12 +0800
Subject: [PATCH] Remove `Send` trait bound from `NonNullPtr`

---
 ostd/src/sync/rcu/mod.rs          | 18 +++++++++---------
 ostd/src/sync/rcu/non_null/mod.rs |  8 ++++----
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/ostd/src/sync/rcu/mod.rs b/ostd/src/sync/rcu/mod.rs
index 8a86db13..53e81691 100644
--- a/ostd/src/sync/rcu/mod.rs
+++ b/ostd/src/sync/rcu/mod.rs
@@ -121,7 +121,7 @@ unsafe impl<P: NonNullPtr> Send for RcuInner<P> where P: Send {}
 //     of `P` created on another thread.
 unsafe impl<P: NonNullPtr> Sync for RcuInner<P> where P: Send + Sync {}
 
-impl<P: NonNullPtr> RcuInner<P> {
+impl<P: NonNullPtr + Send> RcuInner<P> {
     const fn new_none() -> Self {
         Self {
             ptr: AtomicPtr::new(core::ptr::null_mut()),
@@ -200,7 +200,7 @@ struct RcuReadGuardInner<'a, P: NonNullPtr> {
     _inner_guard: DisabledPreemptGuard,
 }
 
-impl<P: NonNullPtr> RcuReadGuardInner<'_, P> {
+impl<P: NonNullPtr + Send> RcuReadGuardInner<'_, P> {
     fn get(&self) -> Option<P::Ref<'_>> {
         // SAFETY: The guard ensures that `P` will not be dropped. Thus, `P`
         // outlives the lifetime of `&self`. Additionally, during this period,
@@ -240,7 +240,7 @@ impl<P: NonNullPtr> RcuReadGuardInner<'_, P> {
     }
 }
 
-impl<P: NonNullPtr> Rcu<P> {
+impl<P: NonNullPtr + Send> Rcu<P> {
     /// Creates a new RCU primitive with the given pointer.
     pub fn new(pointer: P) -> Self {
         Self(RcuInner::new(pointer))
@@ -281,7 +281,7 @@ impl<P: NonNullPtr> Rcu<P> {
     }
 }
 
-impl<P: NonNullPtr> RcuOption<P> {
+impl<P: NonNullPtr + Send> RcuOption<P> {
     /// Creates a new RCU primitive with the given pointer.
     pub fn new(pointer: Option<P>) -> Self {
         if let Some(pointer) = pointer {
@@ -336,7 +336,7 @@ impl<P: NonNullPtr> RcuOption<P> {
     }
 }
 
-impl<P: NonNullPtr> RcuReadGuard<'_, P> {
+impl<P: NonNullPtr + Send> RcuReadGuard<'_, P> {
     /// Gets the reference of the protected data.
     pub fn get(&self) -> P::Ref<'_> {
         self.0.get().unwrap()
@@ -362,7 +362,7 @@ impl<P: NonNullPtr> RcuReadGuard<'_, P> {
     }
 }
 
-impl<P: NonNullPtr> RcuOptionReadGuard<'_, P> {
+impl<P: NonNullPtr + Send> RcuOptionReadGuard<'_, P> {
     /// Gets the reference of the protected data.
     ///
     /// If the RCU primitive protects nothing, this function returns `None`.
@@ -398,12 +398,12 @@ impl<P: NonNullPtr> RcuOptionReadGuard<'_, P> {
 ///
 /// The pointer must be previously returned by `into_raw` and the pointer
 /// must be only be dropped once.
-unsafe fn delay_drop<P: NonNullPtr>(pointer: NonNull<<P as NonNullPtr>::Target>) {
-    struct ForceSend<P: NonNullPtr>(NonNull<<P as NonNullPtr>::Target>);
+unsafe fn delay_drop<P: NonNullPtr + Send>(pointer: NonNull<<P as NonNullPtr>::Target>) {
+    struct ForceSend<P: NonNullPtr + Send>(NonNull<<P as NonNullPtr>::Target>);
     // SAFETY: Sending a raw pointer to another task is safe as long as
     // the pointer access in another task is safe (guaranteed by the trait
     // bound `P: Send`).
-    unsafe impl<P: NonNullPtr> Send for ForceSend<P> {}
+    unsafe impl<P: NonNullPtr + Send> Send for ForceSend<P> {}
 
     let pointer: ForceSend<P> = ForceSend(pointer);
 
diff --git a/ostd/src/sync/rcu/non_null/mod.rs b/ostd/src/sync/rcu/non_null/mod.rs
index 7ed0d773..a0b1b800 100644
--- a/ostd/src/sync/rcu/non_null/mod.rs
+++ b/ostd/src/sync/rcu/non_null/mod.rs
@@ -23,7 +23,7 @@ use crate::prelude::*;
 /// raw pointers.
 ///
 /// [`Rcu`]: super::Rcu
-pub unsafe trait NonNullPtr: Send + 'static {
+pub unsafe trait NonNullPtr: 'static {
     /// The target type that this pointer refers to.
     // TODO: Support `Target: ?Sized`.
     type Target;
@@ -102,7 +102,7 @@ impl<'a, T> BoxRef<'a, T> {
     }
 }
 
-unsafe impl<T: Send + 'static> NonNullPtr for Box<T> {
+unsafe impl<T: 'static> NonNullPtr for Box<T> {
     type Target = T;
 
     type Ref<'a>
@@ -164,7 +164,7 @@ impl<'a, T> ArcRef<'a, T> {
     }
 }
 
-unsafe impl<T: Send + Sync + 'static> NonNullPtr for Arc<T> {
+unsafe impl<T: 'static> NonNullPtr for Arc<T> {
     type Target = T;
 
     type Ref<'a>
@@ -218,7 +218,7 @@ impl<T> Deref for WeakRef<'_, T> {
     }
 }
 
-unsafe impl<T: Send + Sync + 'static> NonNullPtr for Weak<T> {
+unsafe impl<T: 'static> NonNullPtr for Weak<T> {
     type Target = T;
 
     type Ref<'a>