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Auto merge of #113861 - ibraheemdev:mpsc-tls-bug, r=Mark-Simulacrum 

Avoid tls access while iterating through mpsc thread entries

Upstream fix: https://github.com/crossbeam-rs/crossbeam/pull/802. Possibly fixes https://github.com/rust-lang/rust/issues/113726.
This commit is contained in:
bors 2023-07-20 12:30:12 +00:00
parent b14fd2359f fb31a1ac21
commit 6b53175b5d
1 changed files with 26 additions and 20 deletions
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46
library/std/src/sync/mpmc/waker.rs
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@ -66,26 +66,32 @@ impl Waker {
/// Attempts to find another thread's entry, select the operation, and wake it up.
#[inline]
pub(crate) fn try_select(&mut self) -> Option<Entry> {
self.selectors
.iter()
.position(|selector| {
// Does the entry belong to a different thread?
selector.cx.thread_id() != current_thread_id()
&& selector // Try selecting this operation.
.cx
.try_select(Selected::Operation(selector.oper))
.is_ok()
&& {
// Provide the packet.
selector.cx.store_packet(selector.packet);
// Wake the thread up.
selector.cx.unpark();
true
}
})
// Remove the entry from the queue to keep it clean and improve
// performance.
.map(|pos| self.selectors.remove(pos))
if self.selectors.is_empty() {
None
} else {
let thread_id = current_thread_id();
self.selectors
.iter()
.position(|selector| {
// Does the entry belong to a different thread?
selector.cx.thread_id() != thread_id
&& selector // Try selecting this operation.
.cx
.try_select(Selected::Operation(selector.oper))
.is_ok()
&& {
// Provide the packet.
selector.cx.store_packet(selector.packet);
// Wake the thread up.
selector.cx.unpark();
true
}
})
// Remove the entry from the queue to keep it clean and improve
// performance.
.map(|pos| self.selectors.remove(pos))
}
}
/// Notifies all operations waiting to be ready.