rust/kernel/sync/poll.rs

Source file repositories/reference/linux-study-clean/rust/kernel/sync/poll.rs

File Facts

System
Linux kernel
Corpus path
rust/kernel/sync/poll.rs
Extension
.rs
Size
3317 bytes
Lines
107
Domain
Rust Kernel Layer
Bucket
Rust API Membrane
Inferred role
Rust Kernel Layer: implementation source
Status
source implementation candidate

Why This File Exists

Rust-side wrappers and abstractions around kernel C APIs, ownership contracts, allocation, synchronization, and module integration.

Dependency Surface

Detected Declarations

Annotated Snippet

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) }
    }
}

/// A wrapper around [`CondVar`] that makes it usable with [`PollTable`].
///
/// [`CondVar`]: crate::sync::CondVar
#[pin_data(PinnedDrop)]
pub struct PollCondVar {
    #[pin]
    inner: CondVar,
}

impl PollCondVar {
    /// Constructs a new condvar initialiser.
    pub fn new(name: &'static CStr, key: Pin<&'static LockClassKey>) -> impl PinInit<Self> {
        pin_init!(Self {
            inner <- CondVar::new(name, key),
        })
    }
}

// Make the `CondVar` methods callable on `PollCondVar`.
impl Deref for PollCondVar {
    type Target = CondVar;

    fn deref(&self) -> &CondVar {
        &self.inner
    }
}

#[pinned_drop]
impl PinnedDrop for PollCondVar {
    #[inline]
    fn drop(self: Pin<&mut Self>) {
        // Clear anything registered using `register_wait`.
        //
        // SAFETY: The pointer points at a valid `wait_queue_head`.
        unsafe { bindings::__wake_up_pollfree(self.inner.wait_queue_head.get()) };

        // Wait for epoll items to be properly removed.
        //
        // SAFETY: Just an FFI call.
        unsafe { bindings::synchronize_rcu() };
    }
}

Annotation

Implementation Notes