RE: [PATCH 62/79] block: rust: add `TagSet::update_hw_queue_count`

[Ken Kurematsu]

Hi Andreas,

> -----Original Message-----
> From: Andreas Hindborg <a.hindborg@xxxxxxxxxx>
> Sent: Monday, February 16, 2026 8:36 AM
> To: Boqun Feng <boqun.feng@xxxxxxxxx>; Jens Axboe <axboe@xxxxxxxxx>;
> Miguel Ojeda <ojeda@xxxxxxxxxx>; Gary Guo <gary@xxxxxxxxxxx>; Björn Roy
> Baron <bjorn3_gh@xxxxxxxxxxxxxx>; Benno Lossin <lossin@xxxxxxxxxx>;
> Alice Ryhl <aliceryhl@xxxxxxxxxx>; Trevor Gross <tmgross@xxxxxxxxx>;
> Danilo Krummrich <dakr@xxxxxxxxxx>; FUJITA Tomonori
> <fujita.tomonori@xxxxxxxxx>; Frederic Weisbecker <frederic@xxxxxxxxxx>;
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> Anna-Maria Behnsen <anna-maria@xxxxxxxxxxxxx>; John Stultz
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> <Liam.Howlett@xxxxxxxxxx>
> Cc: linux-block@xxxxxxxxxxxxxxx; rust-for-linux@xxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx; Andreas Hindborg
> <a.hindborg@xxxxxxxxxx>
> Subject: [PATCH 62/79] block: rust: add `TagSet::update_hw_queue_count`
> 
> Add a method to `TagSet` that allows changing the number of hardware
> queues
> dynamically.
> 
> Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxx>
> ---
>  rust/kernel/block/mq/tag_set.rs | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/rust/kernel/block/mq/tag_set.rs
> b/rust/kernel/block/mq/tag_set.rs
> index 4d00979a83dbd..47a162360e628 100644
> --- a/rust/kernel/block/mq/tag_set.rs
> +++ b/rust/kernel/block/mq/tag_set.rs
> @@ -8,6 +8,7 @@
>      bindings,
>      block::mq::{operations::OperationsVTable, request::RequestDataWrapper,
> Operations},
>      error::{self, Result},
> +    prelude::*,
>      try_pin_init,
>      types::{ForeignOwnable, Opaque},
>  };
> @@ -34,7 +35,7 @@ pub struct TagSet<T: Operations> {
>  }
> 
>  impl<T: Operations> TagSet<T> {
> -    /// Try to create a new tag set
> +    /// Try to create a new tag se }t

Is this a typo?
It looks like an unnecessary ' }'.

>      pub fn new(
>          nr_hw_queues: u32,
>          tagset_data: T::TagSetData,
> @@ -142,6 +143,20 @@ pub fn hw_queue_count(&self) -> u32 {
>          unsafe { (*self.inner.get()).nr_hw_queues }
>      }
> 
> +    /// Update the number of hardware queues for this tag set.
> +    ///
> +    /// This operation may fail if memory for tags cannot be allocated.
> +    pub fn update_hw_queue_count(&self, nr_hw_queues: u32) -> Result {
> +        // SAFETY: blk_mq_update_nr_hw_queues applies internal
> synchronization.
> +        unsafe { bindings::blk_mq_update_nr_hw_queues(self.inner.get(),
> nr_hw_queues) }
> +
> +        if self.hw_queue_count() == nr_hw_queues {
> +            Ok(())
> +        } else {
> +            Err(ENOMEM)
> +        }
> +    }
> +
>      /// Borrow the [`T::TagSetData`] associated with this tag set.
>      pub fn data(&self) -> <T::TagSetData as
> ForeignOwnable>::Borrowed<'_> {
>          // SAFETY: By type invariant, `self.inner` is valid.
> 
> --
> 2.51.2
> 
> 

Best regards,
Ken Kurematsu