Re: [PATCH] rust: sync: export lock::do_unlocked

["Benno Lossin" <lossin@kernel.org>]

On Sun Feb 15, 2026 at 9:15 PM CET, Andreas Hindborg wrote:
> Export lock::do_unlocked publicly. Add documentation for the method.
>
> Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>

Reviewed-by: Benno Lossin <lossin@kernel.org>

> ---
>  rust/kernel/sync/lock.rs | 26 +++++++++++++++++++++++++-
>  1 file changed, 25 insertions(+), 1 deletion(-)
>
> diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
> index 46a57d1fc309d..f390cd7ba0762 100644
> --- a/rust/kernel/sync/lock.rs
> +++ b/rust/kernel/sync/lock.rs
> @@ -235,7 +235,31 @@ pub fn lock_ref(&self) -> &'a Lock<T, B> {
>          self.lock
>      }
>  
> -    pub(crate) fn do_unlocked<U>(&mut self, cb: impl FnOnce() -> U) -> U {
> +    /// Temporarily unlock the lock to execute the given closure.
> +    ///
> +    /// This method unlocks the lock before calling the closure `cb`, and re-locks it afterwards.
> +    /// This is useful when you need to perform operations that are not allowed while holding
> +    /// certain locks, such as allocating memory (which is prohibited while holding a spinlock).
> +    ///
> +    /// # Examples
> +    ///
> +    /// ```
> +    /// # use kernel::{new_spinlock, prelude::*};
> +    /// # use pin_init::stack_pin_init;
> +    ///
> +    /// stack_pin_init!{
> +    ///     let lock = new_spinlock!(())
> +    /// }
> +    ///
> +    /// let mut guard = lock.lock();
> +    /// let mut buffer = KVec::new();
> +    /// // Temporarily unlock to allocate memory, which should not be done while holding a spinlock.
> +    ///  guard.do_unlocked(|| {
           ^
Spurious space.

Cheers,
Benno

> +    ///     buffer.push(5u32, GFP_KERNEL)
> +    /// })?;
> +    /// # Ok::<(), Error>(())
> +    /// ```
> +    pub fn do_unlocked<U>(&mut self, cb: impl FnOnce() -> U) -> U {
>          // SAFETY: The caller owns the lock, so it is safe to unlock it.
>          unsafe { B::unlock(self.lock.state.get(), &self.state) };
>  
>
> ---
> base-commit: 05f7e89ab9731565d8a62e3b5d1ec206485eeb0b
> change-id: 20260215-export-do-unlocked-00a6ac9373d4
>
> Best regards,