tokio: avoid temporary references in Link impls #4841

Darksonn · 2022-07-18T19:25:35Z

Tokio uses temporary references in implementations of Link when mapping between a raw pointer for a struct, and a raw pointer for a field. This causes all sorts of miri-related issues. This PR avoids that.

Darksonn · 2022-07-18T19:46:30Z

tokio/src/runtime/task/core.rs

-    pub(super) owned: UnsafeCell<linked_list::Pointers<Header>>,
+    pub(super) owned: linked_list::Pointers<Header>,


This is ok since Pointers already contains an UnsafeCell.

tokio/tokio/src/util/linked_list.rs

Lines 70 to 73 in 922fc91

/// Previous / next pointers.

pub(crate) struct Pointers<T> {

inner: UnsafeCell<PointersInner<T>>,

}

Darksonn · 2022-07-18T19:57:05Z

tokio/src/time/driver/entry.rs

-#[repr(C)] // required by `link_list::Link` impl
+#[repr(C)]


Do we keep this?

you tell me

🤷‍♀️

The layout is pretty stupid if they're not in the order written here. I guess we will keep it. (Though Rust would always pick the same layout, at least today.)

This PR contains the following updates: | Package | Type | Update | Change | |---|---|---|---| | [tokio](https://tokio.rs) ([source](https://github.com/tokio-rs/tokio)) | dependencies | minor | `1.20.1` -> `1.21.0` | | [tokio](https://tokio.rs) ([source](https://github.com/tokio-rs/tokio)) | dev-dependencies | minor | `1.20.1` -> `1.21.0` | --- ### Release Notes <details> <summary>tokio-rs/tokio</summary> ### [`v1.21.0`](https://github.com/tokio-rs/tokio/releases/tag/tokio-1.21.0) [Compare Source](tokio-rs/tokio@tokio-1.20.1...tokio-1.21.0) ##### 1.21.0 (September 2, 2022) This release is the first release of Tokio to intentionally support WASM. The `sync,macros,io-util,rt,time` features are stabilized on WASM. Additionally the wasm32-wasi target is given unstable support for the `net` feature. ##### Added - net: add `device` and `bind_device` methods to TCP/UDP sockets ([#4882]) - net: add `tos` and `set_tos` methods to TCP and UDP sockets ([#4877]) - net: add security flags to named pipe `ServerOptions` ([#4845]) - signal: add more windows signal handlers ([#4924]) - sync: add `mpsc::Sender::max_capacity` method ([#4904]) - sync: implement Weak version of `mpsc::Sender` ([#4595]) - task: add `LocalSet::enter` ([#4765]) - task: stabilize `JoinSet` and `AbortHandle` ([#4920]) - tokio: add `track_caller` to public APIs ([#4805], [#4848], [#4852]) - wasm: initial support for `wasm32-wasi` target ([#4716]) ##### Fixed - miri: improve miri compatibility by avoiding temporary references in `linked_list::Link` impls ([#4841]) - signal: don't register write interest on signal pipe ([#4898]) - sync: add `#[must_use]` to lock guards ([#4886]) - sync: fix hang when calling `recv` on closed and reopened broadcast channel ([#4867]) - task: propagate attributes on task-locals ([#4837]) ##### Changed - fs: change panic to error in `File::start_seek` ([#4897]) - io: reduce syscalls in `poll_read` ([#4840]) - process: use blocking threadpool for child stdio I/O ([#4824]) - signal: make `SignalKind` methods const ([#4956]) ##### Internal changes - rt: extract `basic_scheduler::Config` ([#4935]) - rt: move I/O driver into `runtime` module ([#4942]) - rt: rename internal scheduler types ([#4945]) ##### Documented - chore: fix typos and grammar ([#4858], [#4894], [#4928]) - io: fix typo in `AsyncSeekExt::rewind` docs ([#4893]) - net: add documentation to `try_read()` for zero-length buffers ([#4937]) - runtime: remove incorrect panic section for `Builder::worker_threads` ([#4849]) - sync: doc of `watch::Sender::send` improved ([#4959]) - task: add cancel safety docs to `JoinHandle` ([#4901]) - task: expand on cancellation of `spawn_blocking` ([#4811]) - time: clarify that the first tick of `Interval::tick` happens immediately ([#4951]) ##### Unstable - rt: add unstable option to disable the LIFO slot ([#4936]) - task: fix incorrect signature in `Builder::spawn_on` ([#4953]) - task: make `task::Builder::spawn*` methods fallible ([#4823]) [#4595]: tokio-rs/tokio#4595 [#4716]: tokio-rs/tokio#4716 [#4765]: tokio-rs/tokio#4765 [#4805]: tokio-rs/tokio#4805 [#4811]: tokio-rs/tokio#4811 [#4823]: tokio-rs/tokio#4823 [#4824]: tokio-rs/tokio#4824 [#4837]: tokio-rs/tokio#4837 [#4840]: tokio-rs/tokio#4840 [#4841]: tokio-rs/tokio#4841 [#4845]: tokio-rs/tokio#4845 [#4848]: tokio-rs/tokio#4848 [#4849]: tokio-rs/tokio#4849 [#4852]: tokio-rs/tokio#4852 [#4858]: tokio-rs/tokio#4858 [#4867]: tokio-rs/tokio#4867 [#4877]: tokio-rs/tokio#4877 [#4882]: tokio-rs/tokio#4882 [#4886]: tokio-rs/tokio#4886 [#4893]: tokio-rs/tokio#4893 [#4894]: tokio-rs/tokio#4894 [#4897]: tokio-rs/tokio#4897 [#4898]: tokio-rs/tokio#4898 [#4901]: tokio-rs/tokio#4901 [#4904]: tokio-rs/tokio#4904 [#4920]: tokio-rs/tokio#4920 [#4924]: tokio-rs/tokio#4924 [#4928]: tokio-rs/tokio#4928 [#4935]: tokio-rs/tokio#4935 [#4936]: tokio-rs/tokio#4936 [#4937]: tokio-rs/tokio#4937 [#4942]: tokio-rs/tokio#4942 [#4945]: tokio-rs/tokio#4945 [#4951]: tokio-rs/tokio#4951 [#4953]: tokio-rs/tokio#4953 [#4956]: tokio-rs/tokio#4956 [#4959]: tokio-rs/tokio#4959 </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this PR and you won't be reminded about these updates again. --- - [ ] If you want to rebase/retry this PR, click this checkbox. --- This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).  Co-authored-by: cabr2-bot <cabr2.help@gmail.com> Reviewed-on: https://codeberg.org/Calciumdibromid/CaBr2/pulls/1532 Reviewed-by: crapStone <crapstone@noreply.codeberg.org> Co-authored-by: Calciumdibromid Bot <cabr2_bot@noreply.codeberg.org> Co-committed-by: Calciumdibromid Bot <cabr2_bot@noreply.codeberg.org>

tokio: avoid temporary references in Link impls

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Darksonn added the A-tokio Area: The main tokio crate label Jul 18, 2022

github-actions bot added the R-loom Run loom tests on this PR label Jul 18, 2022

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Darksonn commented Jul 18, 2022

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carllerche approved these changes Jul 18, 2022

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Darksonn merged commit 6f048ca into master Jul 18, 2022

Darksonn deleted the alice/cleanup-link-impls branch July 18, 2022 20:47

Darksonn mentioned this pull request Jul 25, 2022

chore: fix version detection for addr_of #4863

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Darksonn mentioned this pull request Sep 1, 2022

chore: prepare Tokio v1.21.0 #4967

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tokio: avoid temporary references in Link impls #4841

tokio: avoid temporary references in Link impls #4841

Darksonn commented Jul 18, 2022

Darksonn Jul 18, 2022

Darksonn Jul 18, 2022

carllerche Jul 18, 2022

Darksonn Jul 18, 2022

		pub(super) owned: UnsafeCell<linked_list::Pointers<Header>>,
		pub(super) owned: linked_list::Pointers<Header>,

	/// Previous / next pointers.
	pub(crate) struct Pointers<T> {
	inner: UnsafeCell<PointersInner<T>>,
	}

tokio: avoid temporary references in Link impls #4841

tokio: avoid temporary references in Link impls #4841

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