X Tutup
Skip to content

Save errno inside allow_threads in semaphore acquire #7391

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
youknowone merged 1 commit into from
Mar 10, 2026
+68 −19
Merged

Save errno inside allow_threads in semaphore acquire #7391

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
83 changes: 65 additions & 18 deletions crates/stdlib/src/multiprocessing.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -706,41 +706,69 @@ mod _multiprocessing {

// if (res < 0 && errno == EAGAIN && blocking)
if res < 0 && Errno::last() == Errno::EAGAIN && blocking {
// Couldn't acquire immediately, need to block
// Couldn't acquire immediately, need to block.
//
// Save errno inside the allow_threads closure, before
// attach_thread() runs — matches CPython which saves
// `err = errno` before Py_END_ALLOW_THREADS.

#[cfg(not(target_vendor = "apple"))]
{
let mut saved_errno;
loop {
let sem_ptr = self.handle.as_ptr();
// Py_BEGIN_ALLOW_THREADS / Py_END_ALLOW_THREADS
res = if let Some(ref dl) = deadline {
vm.allow_threads(|| unsafe { libc::sem_timedwait(sem_ptr, dl) })
let (r, e) = if let Some(ref dl) = deadline {
vm.allow_threads(|| {
let r = unsafe { libc::sem_timedwait(sem_ptr, dl) };
(
r,
if r < 0 {
Errno::last()
} else {
Errno::from_raw(0)
},
)
})
} else {
vm.allow_threads(|| unsafe { libc::sem_wait(sem_ptr) })
vm.allow_threads(|| {
let r = unsafe { libc::sem_wait(sem_ptr) };
(
r,
if r < 0 {
Errno::last()
} else {
Errno::from_raw(0)
},
)
})
};
res = r;
saved_errno = e;

if res >= 0 {
break;
}
let err = Errno::last();
if err == Errno::EINTR {
if saved_errno == Errno::EINTR {
vm.check_signals()?;
continue;
}
break;
}
if res < 0 {
return handle_wait_error(vm, saved_errno);
}
}
#[cfg(target_vendor = "apple")]
{
// macOS: use polled fallback since sem_timedwait is not available
if let Some(ref dl) = deadline {
match sem_timedwait_polled(self.handle.as_ptr(), dl, vm) {
Ok(()) => res = 0,
Ok(()) => {}
Err(SemWaitError::Timeout) => {
// Timeout occurred - return false directly
return Ok(false);
}
Err(SemWaitError::SignalException(exc)) => {
// Propagate the original exception (e.g., KeyboardInterrupt)
return Err(exc);
}
Err(SemWaitError::OsError(e)) => {
Expand All @@ -749,31 +777,42 @@ mod _multiprocessing {
}
} else {
// No timeout: use sem_wait (available on macOS)
let mut saved_errno;
loop {
let sem_ptr = self.handle.as_ptr();
res = vm.allow_threads(|| unsafe { libc::sem_wait(sem_ptr) });
let (r, e) = vm.allow_threads(|| {
let r = unsafe { libc::sem_wait(sem_ptr) };
(
r,
if r < 0 {
Errno::last()
} else {
Errno::from_raw(0)
},
)
});
res = r;
saved_errno = e;
if res >= 0 {
break;
}
let err = Errno::last();
if err == Errno::EINTR {
if saved_errno == Errno::EINTR {
vm.check_signals()?;
continue;
}
break;
}
if res < 0 {
return handle_wait_error(vm, saved_errno);
}
}
}
}

// result handling:
if res < 0 {
} else if res < 0 {
// Non-blocking path failed, or blocking=false
let err = Errno::last();
match err {
Errno::EAGAIN | Errno::ETIMEDOUT => return Ok(false),
Errno::EINTR => {
// EINTR should be handled by the check_signals() loop above
// If we reach here, check signals again and propagate any exception
return vm.check_signals().map(|_| false);
}
_ => return Err(os_error(vm, err)),
Expand Down Expand Up @@ -1081,6 +1120,14 @@ mod _multiprocessing {
CString::new(full).map_err(|_| vm.new_value_error("embedded null character"))
}

fn handle_wait_error(vm: &VirtualMachine, saved_errno: Errno) -> PyResult<bool> {
match saved_errno {
Errno::EAGAIN | Errno::ETIMEDOUT => Ok(false),
Errno::EINTR => vm.check_signals().map(|_| false),
_ => Err(os_error(vm, saved_errno)),
}
}

fn os_error(vm: &VirtualMachine, err: Errno) -> PyBaseExceptionRef {
// _PyMp_SetError maps to PyErr_SetFromErrno
let exc_type = match err {
Expand Down
4 changes: 3 additions & 1 deletion crates/vm/src/builtins/tuple.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -108,7 +108,9 @@ impl PyPayload for PyTuple {

#[inline]
unsafe fn freelist_push(obj: *mut PyObject) -> bool {
let len = unsafe { &*(obj as *const crate::Py<PyTuple>) }.elements.len();
let len = unsafe { &*(obj as *const crate::Py<PyTuple>) }
.elements
.len();
if len == 0 || len > TupleFreeList::MAX_SAVE_SIZE {
return false;
}
Expand Down
Loading
X Tutup