5a41bb32dd
Rust Binder cleanup is reworked to match the order in which C Binder cleans up things. A few notes on the changes: * Actually dropping thread objects is done at the very end because they contain a call to synchronize_rcu() which is slow. This ensures that death notifications are sent without waiting for those calls. This avoids failures in rustBinderTest. (The test is already flaky, but this extra sleep makes the flake much more likely to happen.) * We now free refs on remote nodes in release explicitly. Previously that only happened implicitly when everything keeping the ref alive has been dropped. To avoid spurious warnings from this, the warning print about dropping a ref that doesn't exist is only printed if the process is alive. Bug: 431914626 Change-Id: I3d1f4f15ffac7587d1bb0113a41330b2aea69b3d Signed-off-by: Alice Ryhl <aliceryhl@google.com>
110 lines
3.3 KiB
Rust
110 lines
3.3 KiB
Rust
// SPDX-License-Identifier: GPL-2.0
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// Copyright (C) 2024 Google LLC.
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//! Utilities for working with `struct poll_table`.
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use crate::{
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bindings,
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fs::File,
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prelude::*,
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sync::{CondVar, LockClassKey},
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};
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use core::{marker::PhantomData, ops::Deref};
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/// Creates a [`PollCondVar`] initialiser with the given name and a newly-created lock class.
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#[macro_export]
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macro_rules! new_poll_condvar {
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($($name:literal)?) => {
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$crate::sync::poll::PollCondVar::new(
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$crate::optional_name!($($name)?), $crate::static_lock_class!()
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)
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};
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}
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/// Wraps the kernel's `poll_table`.
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///
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/// # Invariants
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///
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/// The pointer must be null or reference a valid `poll_table`.
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#[repr(transparent)]
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pub struct PollTable<'a> {
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table: *mut bindings::poll_table,
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_lifetime: PhantomData<&'a bindings::poll_table>,
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}
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impl<'a> PollTable<'a> {
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/// Creates a [`PollTable`] from a valid pointer.
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///
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/// # Safety
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///
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/// The pointer must be null or reference a valid `poll_table` for the duration of `'a`.
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pub unsafe fn from_raw(table: *mut bindings::poll_table) -> Self {
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// INVARIANTS: The safety requirements are the same as the struct invariants.
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PollTable {
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table,
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_lifetime: PhantomData,
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}
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}
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/// Register this [`PollTable`] with the provided [`PollCondVar`], so that it can be notified
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/// using the condition variable.
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pub fn register_wait(&self, file: &File, cv: &PollCondVar) {
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// SAFETY:
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// * `file.as_ptr()` references a valid file for the duration of this call.
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// * `self.table` is null or references a valid poll_table for the duration of this call.
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// * Since `PollCondVar` is pinned, its destructor is guaranteed to run before the memory
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// containing `cv.wait_queue_head` is invalidated. Since the destructor clears all
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// waiters and then waits for an rcu grace period, it's guaranteed that
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// `cv.wait_queue_head` remains valid for at least an rcu grace period after the removal
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// of the last waiter.
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unsafe { bindings::poll_wait(file.as_ptr(), cv.wait_queue_head.get(), self.table) }
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}
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}
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/// A wrapper around [`CondVar`] that makes it usable with [`PollTable`].
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///
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/// [`CondVar`]: crate::sync::CondVar
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#[pin_data(PinnedDrop)]
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pub struct PollCondVar {
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#[pin]
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inner: CondVar,
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}
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impl PollCondVar {
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/// Constructs a new condvar initialiser.
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pub fn new(name: &'static CStr, key: &'static LockClassKey) -> impl PinInit<Self> {
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pin_init!(Self {
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inner <- CondVar::new(name, key),
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})
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}
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/// Clear anything registered using `register_wait`.
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pub fn clear(&self) {
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// SAFETY: The pointer points at a valid `wait_queue_head`. The destructor waits an rcu
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// grace period before the wait queue is freed.
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unsafe { bindings::__wake_up_pollfree(self.inner.wait_queue_head.get()) };
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}
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}
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// Make the `CondVar` methods callable on `PollCondVar`.
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impl Deref for PollCondVar {
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type Target = CondVar;
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fn deref(&self) -> &CondVar {
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&self.inner
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}
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}
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#[pinned_drop]
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impl PinnedDrop for PollCondVar {
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fn drop(self: Pin<&mut Self>) {
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self.clear();
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// Wait for epoll items to be properly removed.
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//
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// SAFETY: Just an FFI call.
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unsafe { bindings::synchronize_rcu() };
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}
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}
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