rust/tests/pass-dep/concurrency/tls_pthread_drop_order.rs

74 lines
2.6 KiB
Rust

//@ignore-target-windows: No libc on Windows
//! Test that pthread_key destructors are run in the right order.
//! Note that these are *not* used by actual `thread_local!` on Linux! Those use
//! `thread_local_dtor::register_dtor` from the stdlib instead. In Miri this hits the fallback path
//! in `register_dtor_fallback`, which uses a *single* pthread_key to manage a thread-local list of
//! dtors to call.
use std::mem;
use std::ptr;
pub type Key = libc::pthread_key_t;
static mut RECORD: usize = 0;
static mut KEYS: [Key; 2] = [0; 2];
static mut GLOBALS: [u64; 2] = [1, 0];
static mut CANNARY: *mut u64 = ptr::null_mut(); // this serves as a cannary: if TLS dtors are not run properly, this will not get deallocated, making the test fail.
pub unsafe fn create(dtor: Option<unsafe extern "C" fn(*mut u8)>) -> Key {
let mut key = 0;
assert_eq!(libc::pthread_key_create(&mut key, mem::transmute(dtor)), 0);
key
}
pub unsafe fn set(key: Key, value: *mut u8) {
let r = libc::pthread_setspecific(key, value as *mut _);
assert_eq!(r, 0);
}
pub fn record(r: usize) {
assert!(r < 10);
unsafe { RECORD = RECORD * 10 + r };
}
unsafe extern "C" fn dtor(ptr: *mut u64) {
assert!(CANNARY != ptr::null_mut()); // make sure we do not get run too often
let val = *ptr;
let which_key =
GLOBALS.iter().position(|global| global as *const _ == ptr).expect("Should find my global");
record(which_key);
if val > 0 {
*ptr = val - 1;
set(KEYS[which_key], ptr as *mut _);
}
// Check if the records matches what we expect. If yes, clear the cannary.
// If the record is wrong, the cannary will never get cleared, leading to a leak -> test fails.
// If the record is incomplete (i.e., more dtor calls happen), the check at the beginning of this function will fail -> test fails.
// The correct sequence is: First key 0, then key 1, then key 0.
// Note that this relies on dtor order, which is not specified by POSIX, but seems to be
// consistent between Miri and Linux currently (as of Aug 2022).
if RECORD == 0_1_0 {
drop(Box::from_raw(CANNARY));
CANNARY = ptr::null_mut();
}
}
fn main() {
unsafe {
create(None); // check that the no-dtor case works
// Initialize the keys we use to check destructor ordering
for (key, global) in KEYS.iter_mut().zip(GLOBALS.iter_mut()) {
*key = create(Some(mem::transmute(dtor as unsafe extern "C" fn(*mut u64))));
set(*key, global as *mut _ as *mut u8);
}
// Initialize cannary
CANNARY = Box::into_raw(Box::new(0u64));
}
}