Re: [PATCH 2/2] rust: sync: add `CondVar::wait_timeout`

[Martin Rodriguez Reboredo <yakoyoku@gmail.com>]

On 12/6/23 07:09, Alice Ryhl wrote:
> Sleep on a condition variable with a timeout.
> 
> This is used by Rust Binder for process freezing. There, we want to
> sleep until the freeze operation completes, but we want to be able to
> abort the process freezing if it doesn't complete within some timeout.
> 
> Signed-off-by: Alice Ryhl <aliceryhl@google.com>
> ---
> [...]
>   
> +    /// Atomically releases the given lock (whose ownership is proven by the guard) and puts the
> +    /// thread to sleep. It wakes up when notified by [`CondVar::notify_one`] or
> +    /// [`CondVar::notify_all`], or when the thread receives a signal.
> +    ///
> +    /// Returns whether there is a signal pending.

Remaining jiffies or zero on timeout?

> +    fn wait_internal_timeout<T, B>(
> +        &self,
> +        wait_state: u32,
> +        guard: &mut Guard<'_, T, B>,
> +        timeout: u64,
> +    ) -> u64
> [...]
> +
> +    /// Releases the lock and waits for a notification in interruptible mode.
> +    ///
> +    /// Atomically releases the given lock (whose ownership is proven by the guard) and puts the
> +    /// thread to sleep. It wakes up when notified by [`CondVar::notify_one`] or
> +    /// [`CondVar::notify_all`], or when a timeout occurs, or when the thread receives a signal.
> +    ///
> +    /// Returns whether there is a signal pending.

This one is correct.

> +    #[must_use = "wait_timeout returns if a signal is pending, so the caller must check the return value"]
> +    pub fn wait_timeout<T: ?Sized, B: Backend>(
> +        &self,
> +        guard: &mut Guard<'_, T, B>,
> +        jiffies: u64,
> +    ) -> CondVarTimeoutResult {
> [...]