On Thu Jun 26, 2025 at 10:00 PM CEST, Danilo Krummrich wrote:
> diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
> index 60b86f370284..47653c14838b 100644
> --- a/drivers/gpu/nova-core/gpu.rs
> +++ b/drivers/gpu/nova-core/gpu.rs
> @@ -161,14 +161,14 @@ fn new(bar: &Bar0) -> Result<Spec> {
> pub(crate) struct Gpu {
> spec: Spec,
> /// MMIO mapping of PCI BAR 0
> - bar: Devres<Bar0>,
> + bar: Arc<Devres<Bar0>>,
Can't you store it inline, given that you return an `impl PinInit<Self>`
below?
> fw: Firmware,
> }
>
> impl Gpu {
> pub(crate) fn new(
> pdev: &pci::Device<device::Bound>,
> - devres_bar: Devres<Bar0>,
> + devres_bar: Arc<Devres<Bar0>>,
> ) -> Result<impl PinInit<Self>> {
While I see this code, is it really necessary to return `Result`
wrapping the initializer here? I think it's probably better to return
`impl PinInit<Self, Error>` instead. (of course in a different patch/an
issue)
> let bar = devres_bar.access(pdev.as_ref())?;
> let spec = Spec::new(bar)?;
> @@ -44,6 +49,10 @@ struct DevresInner<T: Send> {
> /// [`Devres`] users should make sure to simply free the corresponding backing resource in `T`'s
> /// [`Drop`] implementation.
> ///
> +/// # Invariants
> +///
> +/// [`Self::inner`] is guaranteed to be initialized and is always accessed read-only.
> +///
Let's put this section below the examples, I really ought to write the
safety docs one day and let everyone vote on this kind of stuff...
> /// # Example
> ///
> /// ```no_run
> @@ -213,44 +233,63 @@ pub fn new(dev: &Device<Bound>, data: T, flags: Flags) -> Result<Self> {
> /// }
> /// ```
> pub fn access<'a>(&'a self, dev: &'a Device<Bound>) -> Result<&'a T> {
> - if self.0.dev.as_raw() != dev.as_raw() {
> + if self.dev.as_raw() != dev.as_raw() {
> return Err(EINVAL);
> }
>
> // SAFETY: `dev` being the same device as the device this `Devres` has been created for
> - // proves that `self.0.data` hasn't been revoked and is guaranteed to not be revoked as
> - // long as `dev` lives; `dev` lives at least as long as `self`.
> - Ok(unsafe { self.0.data.access() })
> + // proves that `self.data` hasn't been revoked and is guaranteed to not be revoked as long
> + // as `dev` lives; `dev` lives at least as long as `self`.
What if the device has been unbound and a new device has been allocated
in the exact same memory?
---
Cheers,
Benno
> + Ok(unsafe { self.data().access() })
> }
