From: Danilo Krummrich Date: Mon, 25 May 2026 20:21:05 +0000 (+0200) Subject: rust: pci: make Bar lifetime-parameterized X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8ea0b6d5bef5e4f4637964c3b2cf732d9bf4f408;p=thirdparty%2Fkernel%2Flinux.git rust: pci: make Bar lifetime-parameterized Convert pci::Bar to pci::Bar<'a, SIZE>, storing &'a Device to tie the BAR mapping lifetime to the device. iomap_region_sized() now returns Result> directly instead of impl PinInit>, Error>. Since the lifetime ties the mapping to the device's bound state, callers no longer need Devres for the common case where the Bar lives in the driver's private data. Add Bar::into_devres() to consume the bar and register it as a device-managed resource, returning Devres>. The lifetime is erased to 'static because Devres guarantees the bar does not actually outlive the device -- access is revoked on unbind. Reviewed-by: Eliot Courtney Reviewed-by: Greg Kroah-Hartman Reviewed-by: Alexandre Courbot Reviewed-by: Gary Guo Link: https://patch.msgid.link/20260525202921.124698-19-dakr@kernel.org Signed-off-by: Danilo Krummrich --- diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs index 6ad1a856694ce..7dbec0470c26c 100644 --- a/drivers/gpu/nova-core/driver.rs +++ b/drivers/gpu/nova-core/driver.rs @@ -45,7 +45,7 @@ const BAR0_SIZE: usize = SZ_16M; // DMA addresses. These systems should be quite rare. const GPU_DMA_BITS: u32 = 47; -pub(crate) type Bar0 = pci::Bar; +pub(crate) type Bar0 = pci::Bar<'static, BAR0_SIZE>; kernel::pci_device_table!( PCI_TABLE, @@ -92,8 +92,9 @@ impl pci::Driver for NovaCore { // other threads of execution. unsafe { pdev.dma_set_mask_and_coherent(DmaMask::new::())? }; - let bar = Arc::pin_init( - pdev.iomap_region_sized::(0, c"nova-core/bar0"), + let bar = Arc::new( + pdev.iomap_region_sized::(0, c"nova-core/bar0")? + .into_devres()?, GFP_KERNEL, )?; diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs index fd4633f977f60..82cbd8b969fb1 100644 --- a/rust/kernel/devres.rs +++ b/rust/kernel/devres.rs @@ -304,7 +304,7 @@ impl Devres { /// pci, // /// }; /// - /// fn from_core(dev: &pci::Device>, devres: Devres>) -> Result { + /// fn from_core(dev: &pci::Device>, devres: Devres>) -> Result { /// let bar = devres.access(dev.as_ref())?; /// /// let _ = bar.read32(0x0); diff --git a/rust/kernel/pci/io.rs b/rust/kernel/pci/io.rs index 3ce21482b0797..0461e01aaa20e 100644 --- a/rust/kernel/pci/io.rs +++ b/rust/kernel/pci/io.rs @@ -14,8 +14,7 @@ use crate::{ Mmio, MmioRaw, // }, - prelude::*, - sync::aref::ARef, // + prelude::*, // }; use core::{ marker::PhantomData, @@ -146,14 +145,18 @@ impl<'a, S: ConfigSpaceKind> IoKnownSize for ConfigSpace<'a, S> { /// /// `Bar` always holds an `IoRaw` instance that holds a valid pointer to the start of the I/O /// memory mapped PCI BAR and its size. -pub struct Bar { - pdev: ARef, +pub struct Bar<'a, const SIZE: usize = 0> { + pdev: &'a Device, io: MmioRaw, num: i32, } -impl Bar { - pub(super) fn new(pdev: &Device, num: u32, name: &'static CStr) -> Result { +impl<'a, const SIZE: usize> Bar<'a, SIZE> { + pub(super) fn new( + pdev: &'a Device, + num: u32, + name: &'static CStr, + ) -> Result { let len = pdev.resource_len(num)?; if len == 0 { return Err(ENOMEM); @@ -196,11 +199,7 @@ impl Bar { } }; - Ok(Bar { - pdev: pdev.into(), - io, - num, - }) + Ok(Bar { pdev, io, num }) } /// # Safety @@ -219,11 +218,24 @@ impl Bar { fn release(&self) { // SAFETY: The safety requirements are guaranteed by the type invariant of `self.pdev`. - unsafe { Self::do_release(&self.pdev, self.io.addr(), self.num) }; + unsafe { Self::do_release(self.pdev, self.io.addr(), self.num) }; + } + + /// Consume the `Bar` and register it as a device-managed resource. + /// + /// The returned `Devres>` can outlive the original lifetime `'a`. Access + /// to the BAR is revoked when the device is unbound. + pub fn into_devres(self) -> Result>> { + // SAFETY: Casting to `'static` is sound because `Devres` guarantees the `Bar` does not + // actually outlive the device -- access is revoked and the resource is released when the + // device is unbound. + let bar: Bar<'static, SIZE> = unsafe { core::mem::transmute(self) }; + let pdev = bar.pdev; + Devres::new(pdev.as_ref(), bar) } } -impl Bar { +impl Bar<'_> { #[inline] pub(super) fn index_is_valid(index: u32) -> bool { // A `struct pci_dev` owns an array of resources with at most `PCI_NUM_RESOURCES` entries. @@ -231,13 +243,13 @@ impl Bar { } } -impl Drop for Bar { +impl Drop for Bar<'_, SIZE> { fn drop(&mut self) { self.release(); } } -impl Deref for Bar { +impl Deref for Bar<'_, SIZE> { type Target = Mmio; fn deref(&self) -> &Self::Target { @@ -253,16 +265,12 @@ impl Device { &'a self, bar: u32, name: &'static CStr, - ) -> impl PinInit>, Error> + 'a { - Devres::new(self.as_ref(), Bar::::new(self, bar, name)) + ) -> Result> { + Bar::new(self, bar, name) } /// Maps an entire PCI BAR after performing a region-request on it. - pub fn iomap_region<'a>( - &'a self, - bar: u32, - name: &'static CStr, - ) -> impl PinInit, Error> + 'a { + pub fn iomap_region<'a>(&'a self, bar: u32, name: &'static CStr) -> Result> { self.iomap_region_sized::<0>(bar, name) } diff --git a/samples/rust/rust_driver_pci.rs b/samples/rust/rust_driver_pci.rs index 6791d98e1c79f..0353481b0690d 100644 --- a/samples/rust/rust_driver_pci.rs +++ b/samples/rust/rust_driver_pci.rs @@ -45,7 +45,7 @@ mod regs { pub(super) const END: usize = 0x10; } -type Bar0 = pci::Bar<{ regs::END }>; +type Bar0 = pci::Bar<'static, { regs::END }>; #[derive(Copy, Clone, Debug)] struct TestIndex(u8); @@ -161,7 +161,8 @@ impl pci::Driver for SampleDriver { pdev.set_master(); Ok(try_pin_init!(Self { - bar <- pdev.iomap_region_sized::<{ regs::END }>(0, c"rust_driver_pci"), + bar: pdev.iomap_region_sized::<{ regs::END }>(0, c"rust_driver_pci")? + .into_devres()?, index: *info, _: { let bar = bar.access(pdev.as_ref())?;