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Auto merge of #105426 - flba-eb:fix_tls_destructor_unwinding, r=m-ou-se

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Catch panics/unwinding in destruction of TLS values

`destroy_value` is/can be called from C code (libc). Unwinding from Rust to C code is undefined behavior, which is why unwinding is caught here.

This problem caused an infinite loop inside the unwinding code when running `src/test/ui/threads-sendsync/issue-24313.rs` on a tier 3 target (QNX/Neutrino) on aarch64.

See also https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/Infinite.20unwinding.20bug.
This commit is contained in:
bors 2022-12-30 12:58:50 +00:00
commit 7c991868c6
1 changed files with 14 additions and 7 deletions
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21
library/std/src/thread/local.rs
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@ -905,9 +905,8 @@ pub mod statik {
pub mod fast {
use super::lazy::LazyKeyInner;
use crate::cell::Cell;
use crate::fmt;
use crate::mem;
use crate::sys::thread_local_dtor::register_dtor;
use crate::{fmt, mem, panic};
#[derive(Copy, Clone)]
enum DtorState {
@ -1028,10 +1027,15 @@ pub mod fast {
// `Option<T>` to `None`, and `dtor_state` to `RunningOrHasRun`. This
// causes future calls to `get` to run `try_initialize_drop` again,
// which will now fail, and return `None`.
unsafe {
//
// Wrap the call in a catch to ensure unwinding is caught in the event
// a panic takes place in a destructor.
if let Err(_) = panic::catch_unwind(panic::AssertUnwindSafe(|| unsafe {
let value = (*ptr).inner.take();
(*ptr).dtor_state.set(DtorState::RunningOrHasRun);
drop(value);
})) {
rtabort!("thread local panicked on drop");
}
}
}
@ -1044,10 +1048,8 @@ pub mod fast {
pub mod os {
use super::lazy::LazyKeyInner;
use crate::cell::Cell;
use crate::fmt;
use crate::marker;
use crate::ptr;
use crate::sys_common::thread_local_key::StaticKey as OsStaticKey;
use crate::{fmt, marker, panic, ptr};
/// Use a regular global static to store this key; the state provided will then be
/// thread-local.
@ -1137,12 +1139,17 @@ pub mod os {
//
// Note that to prevent an infinite loop we reset it back to null right
// before we return from the destructor ourselves.
unsafe {
//
// Wrap the call in a catch to ensure unwinding is caught in the event
// a panic takes place in a destructor.
if let Err(_) = panic::catch_unwind(|| unsafe {
let ptr = Box::from_raw(ptr as *mut Value<T>);
let key = ptr.key;
key.os.set(ptr::invalid_mut(1));
drop(ptr);
key.os.set(ptr::null_mut());
}) {
rtabort!("thread local panicked on drop");
}
}
}