client_callbacks test fails (hangs) on Raspberry Pi 5 (aarch64)

[worikgh]

Friends

The test clent_callbacks fails (hangs) when running on Raspberry Pi 5, Debian 13.2

My list of failing tests

Running cargo test client_callbacks -- --nocapture

As far as I can tell it hangs when dropping the async_client

The call to j::jack_set_thread_init_callback(client, None, std::ptr::null_mut()); never completes

I am running this test on commit 49d9ad1

I experiencing odd behavior from the dbg! macro. I placed dbg!("jack_set_thread_init_callback"); as the first line of jack_set_thread_init_callback. I see it on x86_64 but not on aarch64. I am unsure what that means

I am out of my depth, never having done FFI in Rust before, so I am feeling my way.

[worikgh]

Ok. I have a theory and a fix.

The function that is hanging in jack-sys/src/functions.rs is

pub unsafe fn jack_set_thread_init_callback(
    client: *mut jack_client_t,
    thread_init_callback: JackThreadInitCallback,
    arg: *mut ::libc::c_void,
) {

And:
pub type JackThreadInitCallback = ::std::option::Option<unsafe extern "C" fn(arg: *mut ::libc::c_void) -> ()>;

It hangs when thread_init_callback is None

(The return result of jack_set_thread_init_callback is ignored both places it is called.)

So in jack_set_thread_init_callback not calling jack_set_thread_init_callback_impl if thread_init_callback is None fixes the issue.

What are the implications for other architectures than aarch64? Can this safely be skipped?