Something went wrong. Try again.
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Something went wrong. Try again.
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2024 Google LLC.
//! Utilities for working with `struct poll_table`.
use crate::{ bindings, fs::File, prelude::*, sync::{CondVar, LockClassKey},};use core::{marker::PhantomData, ops::Deref};
/// Creates a [`PollCondVar`] initialiser with the given name and a newly-created lock class.#[macro_export]macro_rules! new_poll_condvar { ($($name:literal)?) => { $crate::sync::poll::PollCondVar::new( $crate::optional_name!($($name)?), $crate::static_lock_class!() ) };}
/// Wraps the kernel's `poll_table`.////// # Invariants////// The pointer must be null or reference a valid `poll_table`.#[repr(transparent)]pub struct PollTable<'a> { table: *mut bindings::poll_table, _lifetime: PhantomData<&'a bindings::poll_table>,}
impl<'a> PollTable<'a> { /// Creates a [`PollTable`] from a valid pointer. /// /// # Safety /// /// 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(&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() }; }}