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std: abort the process on failure to allocate a TLS key

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The panic machinery uses TLS, so panicking if no TLS keys are left can lead to infinite recursion (see https://github.com/rust-lang/rust/issues/140798#issuecomment-2872307377). Rather than having separate logic for the panic count and the thread name, just always abort the process if a TLS key allocation fails. This also has the benefit of aligning the key-based TLS implementation with the documentation, which does not mention that a panic could also occur because of resource exhaustion.
This commit is contained in:
joboet 2025-05-23 18:00:09 +02:00
parent 163cb4ea3f
commit 8bf515330f
No known key found for this signature in database
GPG key ID: 704E0149B0194B3C
2 changed files with 10 additions and 11 deletions
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4
library/std/src/sys/thread_local/key/unix.rs
View file

@ -25,7 +25,9 @@ pub type Key = libc::pthread_key_t;
#[inline]
pub fn create(dtor: Option<unsafe extern "C" fn(*mut u8)>) -> Key {
let mut key = 0;
assert_eq!(unsafe { libc::pthread_key_create(&mut key, mem::transmute(dtor)) }, 0);
if unsafe { libc::pthread_key_create(&mut key, mem::transmute(dtor)) } != 0 {
rtabort!("out of TLS keys");
}
key
}

17
library/std/src/sys/thread_local/key/windows.rs
View file

@ -81,15 +81,10 @@ impl LazyKey {
} else {
let key = unsafe { c::TlsAlloc() };
if key == c::TLS_OUT_OF_INDEXES {
// Wakeup the waiting threads before panicking to avoid deadlock.
unsafe {
c::InitOnceComplete(
self.once.get(),
c::INIT_ONCE_INIT_FAILED,
ptr::null_mut(),
);
}
panic!("out of TLS indexes");
// Since we abort the process, there is no need to wake up
// the waiting threads. If this were a panic, the wakeup
// would need to occur first in order to avoid deadlock.
rtabort!("out of TLS indexes");
}
unsafe {
@ -112,7 +107,9 @@ impl LazyKey {
// If there is no destructor to clean up, we can use racy initialization.
let key = unsafe { c::TlsAlloc() };
assert_ne!(key, c::TLS_OUT_OF_INDEXES, "out of TLS indexes");
if key == c::TLS_OUT_OF_INDEXES {
rtabort!("out of TLS indexes");
}
match self.key.compare_exchange(0, key + 1, AcqRel, Acquire) {
Ok(_) => key,