3 files changed, 32 insertions, 42 deletions

diff --git a/rust/kernel/sync/condvar.rs b/rust/kernel/sync/condvar.rs
index caebf03f553b..c6ec64295c9f 100644
--- a/rust/kernel/sync/condvar.rs
+++ b/rust/kernel/sync/condvar.rs
@@ -216,6 +216,7 @@ impl CondVar {
     /// This method behaves like `notify_one`, except that it hints to the scheduler that the
     /// current thread is about to go to sleep, so it should schedule the target thread on the same
     /// CPU.
+    #[inline]
     pub fn notify_sync(&self) {
         // SAFETY: `wait_queue_head` points to valid memory.
         unsafe { bindings::__wake_up_sync(self.wait_queue_head.get(), TASK_NORMAL) };
@@ -225,6 +226,7 @@ impl CondVar {
     ///
     /// This is not 'sticky' in the sense that if no thread is waiting, the notification is lost
     /// completely (as opposed to automatically waking up the next waiter).
+    #[inline]
     pub fn notify_one(&self) {
         self.notify(1);
     }
@@ -233,6 +235,7 @@ impl CondVar {
     ///
     /// This is not 'sticky' in the sense that if no thread is waiting, the notification is lost
     /// completely (as opposed to automatically waking up the next waiter).
+    #[inline]
     pub fn notify_all(&self) {
         self.notify(0);
     }
diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
index e82fa5be289c..27202beef90c 100644
--- a/rust/kernel/sync/lock.rs
+++ b/rust/kernel/sync/lock.rs
@@ -175,6 +175,8 @@ impl<T: ?Sized, B: Backend> Lock<T, B> {
     /// Tries to acquire the lock.
     ///
     /// 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"]
     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.
diff --git a/rust/kernel/sync/poll.rs b/rust/kernel/sync/poll.rs
index d7e6e59e124b..0ec985d560c8 100644
--- a/rust/kernel/sync/poll.rs
+++ b/rust/kernel/sync/poll.rs
@@ -9,9 +9,8 @@ use crate::{
     fs::File,
     prelude::*,
     sync::{CondVar, LockClassKey},
-    types::Opaque,
 };
-use core::ops::Deref;
+use core::{marker::PhantomData, ops::Deref};
 
 /// Creates a [`PollCondVar`] initialiser with the given name and a newly-created lock class.
 #[macro_export]
@@ -23,58 +22,43 @@ macro_rules! new_poll_condvar {
     };
 }
 
-/// Wraps the kernel's `struct poll_table`.
+/// Wraps the kernel's `poll_table`.
 ///
 /// # Invariants
 ///
-/// This struct contains a valid `struct poll_table`.
-///
-/// For a `struct poll_table` to be valid, its `_qproc` function must follow the safety
-/// requirements of `_qproc` functions:
-///
-/// * The `_qproc` function is given permission to enqueue a waiter to the provided `poll_table`
-///   during the call. Once the waiter is removed and an rcu grace period has passed, it must no
-///   longer access the `wait_queue_head`.
+/// The pointer must be null or reference a valid `poll_table`.
 #[repr(transparent)]
-pub struct PollTable(Opaque<bindings::poll_table>);
+pub struct PollTable<'a> {
+    table: *mut bindings::poll_table,
+    _lifetime: PhantomData<&'a bindings::poll_table>,
+}
 
-impl PollTable {
-    /// Creates a reference to a [`PollTable`] from a valid pointer.
+impl<'a> PollTable<'a> {
+    /// Creates a [`PollTable`] from a valid pointer.
     ///
     /// # Safety
     ///
-    /// The caller must ensure that for the duration of `'a`, the pointer will point at a valid poll
-    /// table (as defined in the type invariants).
-    ///
-    /// The caller must also ensure that the `poll_table` is only accessed via the returned
-    /// reference for the duration of `'a`.
-    pub unsafe fn from_ptr<'a>(ptr: *mut bindings::poll_table) -> &'a mut PollTable {
-        // SAFETY: The safety requirements guarantee the validity of the dereference, while the
-        // `PollTable` type being transparent makes the cast ok.
-        unsafe { &mut *ptr.cast() }
-    }
-
-    fn get_qproc(&self) -> bindings::poll_queue_proc {
-        let ptr = self.0.get();
-        // SAFETY: The `ptr` is valid because it originates from a reference, and the `_qproc`
-        // field is not modified concurrently with this call since we have an immutable reference.
-        unsafe { (*ptr)._qproc }
+    /// The pointer must be null or reference a valid `poll_table` for the duration of `'a`.
+    pub unsafe fn from_raw(table: *mut bindings::poll_table) -> Self {
+        // INVARIANTS: The safety requirements are the same as the struct invariants.
+        PollTable {
+            table,
+            _lifetime: PhantomData,
+        }
     }
 
     /// Register this [`PollTable`] with the provided [`PollCondVar`], so that it can be notified
     /// using the condition variable.
-    pub fn register_wait(&mut self, file: &File, cv: &PollCondVar) {
-        if let Some(qproc) = self.get_qproc() {
-            // SAFETY: The pointers to `file` and `self` need to be valid for the duration of this
-            // call to `qproc`, which they are because they are references.
-            //
-            // The `cv.wait_queue_head` pointer must be valid until an rcu grace period after the
-            // waiter is removed. The `PollCondVar` is pinned, so before `cv.wait_queue_head` can
-            // be destroyed, the destructor must run. That destructor first removes all waiters,
-            // and then waits for an rcu grace period. Therefore, `cv.wait_queue_head` is valid for
-            // long enough.
-            unsafe { qproc(file.as_ptr() as _, cv.wait_queue_head.get(), self.0.get()) };
-        }
+    pub fn register_wait(&self, file: &File, cv: &PollCondVar) {
+        // SAFETY:
+        // * `file.as_ptr()` references a valid file for the duration of this call.
+        // * `self.table` is null or references a valid poll_table for the duration of this call.
+        // * Since `PollCondVar` is pinned, its destructor is guaranteed to run before the memory
+        //   containing `cv.wait_queue_head` is invalidated. Since the destructor clears all
+        //   waiters and then waits for an rcu grace period, it's guaranteed that
+        //   `cv.wait_queue_head` remains valid for at least an rcu grace period after the removal
+        //   of the last waiter.
+        unsafe { bindings::poll_wait(file.as_ptr(), cv.wait_queue_head.get(), self.table) }
     }
 }
 
@@ -107,6 +91,7 @@ impl Deref for PollCondVar {
 
 #[pinned_drop]
 impl PinnedDrop for PollCondVar {
+    #[inline]
     fn drop(self: Pin<&mut Self>) {
         // Clear anything registered using `register_wait`.
         //