diff options
| -rw-r--r-- | library/std/src/sys/common/thread_local/fast_local.rs | 22 | ||||
| -rw-r--r-- | library/std/src/sys/common/thread_local/mod.rs | 21 | ||||
| -rw-r--r-- | library/std/src/thread/mod.rs | 2 |
3 files changed, 33 insertions, 12 deletions
diff --git a/library/std/src/sys/common/thread_local/fast_local.rs b/library/std/src/sys/common/thread_local/fast_local.rs index 447044a798b..bc5da1a1896 100644 --- a/library/std/src/sys/common/thread_local/fast_local.rs +++ b/library/std/src/sys/common/thread_local/fast_local.rs @@ -33,20 +33,21 @@ pub macro thread_local_inner { // 1 == dtor registered, dtor not run // 2 == dtor registered and is running or has run #[thread_local] - static mut STATE: $crate::primitive::u8 = 0; + static STATE: $crate::cell::Cell<$crate::primitive::u8> = $crate::cell::Cell::new(0); + // Safety: Performs `drop_in_place(ptr as *mut $t)`, and requires + // all that comes with it. unsafe extern "C" fn destroy(ptr: *mut $crate::primitive::u8) { - let ptr = ptr as *mut $t; - - unsafe { - $crate::debug_assert_eq!(STATE, 1); - STATE = 2; - $crate::ptr::drop_in_place(ptr); - } + $crate::thread::local_impl::abort_on_dtor_unwind(|| { + let old_state = STATE.replace(2); + $crate::debug_assert_eq!(old_state, 1); + // Safety: safety requirement is passed on to caller. + unsafe { $crate::ptr::drop_in_place(ptr.cast::<$t>()); } + }); } unsafe { - match STATE { + match STATE.get() { // 0 == we haven't registered a destructor, so do // so now. 0 => { @@ -54,7 +55,7 @@ pub macro thread_local_inner { $crate::ptr::addr_of_mut!(VAL) as *mut $crate::primitive::u8, destroy, ); - STATE = 1; + STATE.set(1); $crate::option::Option::Some(&VAL) } // 1 == the destructor is registered and the value @@ -148,7 +149,6 @@ impl<T> fmt::Debug for Key<T> { f.debug_struct("Key").finish_non_exhaustive() } } - impl<T> Key<T> { pub const fn new() -> Key<T> { Key { inner: LazyKeyInner::new(), dtor_state: Cell::new(DtorState::Unregistered) } diff --git a/library/std/src/sys/common/thread_local/mod.rs b/library/std/src/sys/common/thread_local/mod.rs index 77f64588310..975509bd412 100644 --- a/library/std/src/sys/common/thread_local/mod.rs +++ b/library/std/src/sys/common/thread_local/mod.rs @@ -101,3 +101,24 @@ mod lazy { } } } + +/// Run a callback in a scenario which must not unwind (such as a `extern "C" +/// fn` declared in a user crate). If the callback unwinds anyway, then +/// `rtabort` with a message about thread local panicking on drop. +#[inline] +pub fn abort_on_dtor_unwind(f: impl FnOnce()) { + // Using a guard like this is lower cost. + let guard = DtorUnwindGuard; + f(); + core::mem::forget(guard); + + struct DtorUnwindGuard; + impl Drop for DtorUnwindGuard { + #[inline] + fn drop(&mut self) { + // This is not terribly descriptive, but it doesn't need to be as we'll + // already have printed a panic message at this point. + rtabort!("thread local panicked on drop"); + } + } +} diff --git a/library/std/src/thread/mod.rs b/library/std/src/thread/mod.rs index f712c872708..d9973185bc4 100644 --- a/library/std/src/thread/mod.rs +++ b/library/std/src/thread/mod.rs @@ -206,7 +206,7 @@ cfg_if::cfg_if! { #[doc(hidden)] #[unstable(feature = "thread_local_internals", issue = "none")] pub mod local_impl { - pub use crate::sys::common::thread_local::{thread_local_inner, Key}; + pub use crate::sys::common::thread_local::{thread_local_inner, Key, abort_on_dtor_unwind}; } } } |