On Sun, Oct 27, 2024 at 03:42:41PM -0700, Boqun Feng wrote: > Hi Danilo, > > On Tue, Oct 22, 2024 at 11:31:48PM +0200, Danilo Krummrich wrote: > [...] > > +/// The PCI device representation. > > +/// > > +/// A PCI device is based on an always reference counted `device:Device` instance. Cloning a PCI > > +/// device, hence, also increments the base device' reference count. > > +#[derive(Clone)] > > +pub struct Device(ARef<device::Device>); > > + > > Similar to https://lore.kernel.org/rust-for-linux/ZgG7TlybSa00cuoy@boqun-archlinux/ > > Could you also avoid wrapping a point to a PCI device? Instead, wrap the > object type: It's not wrapping a pointer, but an `ARef<device::Device>`. > > #[repr(transparent)] > pub struct Device(Opaque<bindings::pci_dev>); > > impl AlwaysRefCounted for Device { > <put_device() and get_device() on ->dev> > } This implementation is currently implicit, since `pci::Device` just wraps an `ARef<device::Device>` (like any other bus specific device structure does), and hence increments and decrements the reference count of the underlying `struct device` automatically. However, what I dislike about it is that with that, `pci::Device` behaves like an `ARef<T>`, but isn't wrapped by `ARef` itself. Just doing what you proposed is probably cleaner is this aspect, but generates a bit of duplicated code in reference counting the underlying `struct device`. - Danilo > > Regards, > Boqun > > > +impl Device { > > + /// Create a PCI Device instance from an existing `device::Device`. > > + /// > > + /// # Safety > > + /// > > + /// `dev` must be an `ARef<device::Device>` whose underlying `bindings::device` is a member of > > + /// a `bindings::pci_dev`. > > + pub unsafe fn from_dev(dev: ARef<device::Device>) -> Self { > > + Self(dev) > > + } > > + > > + fn as_raw(&self) -> *mut bindings::pci_dev { > > + // SAFETY: By the type invariant `self.0.as_raw` is a pointer to the `struct device` > > + // embedded in `struct pci_dev`. > > + unsafe { container_of!(self.0.as_raw(), bindings::pci_dev, dev) as _ } > > + } > > + > > + /// Enable memory resources for this device. > > + pub fn enable_device_mem(&self) -> Result { > > + // SAFETY: `self.as_raw` is guaranteed to be a pointer to a valid `struct pci_dev`. > > + let ret = unsafe { bindings::pci_enable_device_mem(self.as_raw()) }; > > + if ret != 0 { > > + Err(Error::from_errno(ret)) > > + } else { > > + Ok(()) > > + } > > + } > > + > > + /// Enable bus-mastering for this device. > > + pub fn set_master(&self) { > > + // SAFETY: `self.as_raw` is guaranteed to be a pointer to a valid `struct pci_dev`. > > + unsafe { bindings::pci_set_master(self.as_raw()) }; > > + } > > +} > > + > > +impl AsRef<device::Device> for Device { > > + fn as_ref(&self) -> &device::Device { > > + &self.0 > > + } > > +} > > -- > > 2.46.2 > > > > >
