[BUG] SPI sleep die at async fn with_completion()

[xiaguangbo]

Running 10/s, can cause problem in minutes or seconds. Won't trigger watchdog, but tokio won't run tasks. In async fn with_completion and async fn spi_transmit_async ... fut adding log printing wil greatly reduce the probability of occurrence.
If change the way use SPI, be no occurrence problem.
I'm not sure which sentence has problem for the time being in spi_transmit_async.

No problem:

let mut dbuf = [0u8; 16];

for i in 0..8 {
    self.spi
    .transaction_async(&mut [
        Operation::Write(&[0xc0 + (i * 2) as u8]),
        Operation::Write(&dbuf[i * 2..i * 2 + 2]),
    ])
    .await
    .unwrap();
}

Have problem:

let mut dbuf = [0u8; 16];

self.spi
    .transaction_async(&mut [
        Operation::Write(&[0xc0]),
        Operation::Write(&dbuf[0..16]),
    ])
    .await
    .unwrap();

spi.rs:

async fn with_completion<F, D>(fut: F, dtor: D) -> F::Output
where
    F: Future,
    D: FnMut(bool),
{
    struct Completion<D>
    where
        D: FnMut(bool),
    {
        dtor: D,
        completed: bool,
    }

    impl<D> Drop for Completion<D>
    where
        D: FnMut(bool),
    {
        fn drop(&mut self) {
            (self.dtor)(self.completed);
        }
    }

    let mut completion = Completion {
        dtor,
        completed: false,
    };

    let result = fut.await; // There is acertain chance of stop.

    completion.completed = true;

    result
}

[xiaguangbo]

use sync api