From 9cc63f8bcd560c760d0b12e15bba8f81c86237cf Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 14 Aug 2026 15:43:51 -0700 Subject: Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEAD Changes: Make expedited grace periods expedite normal RCU callbacks Miscellaneous fixes: * Improve diagnostic output with character task states. * Mark accesses to inform KCSAN of concurrency design. * Move from kmalloc() to kmalloc_obj(). * Documentation updates. * Improve handling of RCU deferred quiescent states. * Clean up unused function arguments and structure fields. * Reduce show_rcu_gp_kthreads() stack space. Tasks RCU updates: * Clean up after SRCU re-implementation of Tasks Trace RCU. * Mark accesses to inform KCSAN of concurrency design. * Add ->lazy_timer status to diagnostic output. * Remove an unnecessary memory barrier. * Fix a data race, courtesy of KCSAN. * Documentation updates. * Convert cond_resched_tasks_rcu_qs() from macro to static inline function. SRCU updates: * Add Rust helpers for SRCU. * Avoid losing queued work at cleanup_srcu_struct() time. Torture-test updates: * Preparation work for immediate RCU priority deboosting. * Test RCU readers from real interrupt handlers (as opposed to softirq). * Simplify code through use of cpumask_next_wrap(). * Improve diagnostic output with character task states. * Add rcutorture.nwriters parameter to allow lightweight stall testing, and rcutorture.stall_only to make doing so easier. * Test an RCU Tasks Trace grace period implying an RCU grace period. * Make RCU Tasks Trace torturing track reader batches. * Fix a data race, courtesy of KCSAN. * Plug a shuffle_tmp_mask memory leak on kthread spawn failure. --- samples/rust/rust_dma.rs | 133 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 133 insertions(+) create mode 100644 samples/rust/rust_dma.rs (limited to 'samples/rust/rust_dma.rs') diff --git a/samples/rust/rust_dma.rs b/samples/rust/rust_dma.rs new file mode 100644 index 000000000..5046b4628 --- /dev/null +++ b/samples/rust/rust_dma.rs @@ -0,0 +1,133 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Rust DMA api test (based on QEMU's `pci-testdev`). +//! +//! To make this driver probe, QEMU must be run with `-device pci-testdev`. + +use kernel::{ + device::Core, + dma::{ + Coherent, + DataDirection, + Device, + DmaMask, // + }, + page, pci, + prelude::*, + scatterlist::{Owned, SGTable}, + sync::aref::ARef, +}; + +#[pin_data(PinnedDrop)] +struct DmaSampleDriver { + pdev: ARef, + ca: Coherent<[MyStruct]>, + #[pin] + sgt: SGTable>>, +} + +const TEST_VALUES: [(u32, u32); 5] = [ + (0xa, 0xb), + (0xc, 0xd), + (0xe, 0xf), + (0xab, 0xba), + (0xcd, 0xef), +]; + +struct MyStruct { + h: u32, + b: u32, +} + +impl MyStruct { + fn new(h: u32, b: u32) -> Self { + Self { h, b } + } +} +// SAFETY: All bit patterns are acceptable values for `MyStruct`. +unsafe impl kernel::transmute::AsBytes for MyStruct {} +// SAFETY: Instances of `MyStruct` have no uninitialized portions. +unsafe impl kernel::transmute::FromBytes for MyStruct {} + +kernel::pci_device_table!( + PCI_TABLE, + MODULE_PCI_TABLE, + ::IdInfo, + [(pci::DeviceId::from_id(pci::Vendor::REDHAT, 0x5), ())] +); + +impl pci::Driver for DmaSampleDriver { + type IdInfo = (); + type Data<'bound> = Self; + const ID_TABLE: pci::IdTable = &PCI_TABLE; + + fn probe<'bound>( + pdev: &'bound pci::Device>, + _info: &'bound Self::IdInfo, + ) -> impl PinInit + 'bound { + pin_init::pin_init_scope(move || { + dev_info!(pdev, "Probe DMA test driver.\n"); + + let mask = DmaMask::new::<64>(); + + // SAFETY: There are no concurrent calls to DMA allocation and mapping primitives. + unsafe { pdev.dma_set_mask_and_coherent(mask)? }; + + let ca: Coherent<[MyStruct]> = + Coherent::zeroed_slice(pdev.as_ref(), TEST_VALUES.len(), GFP_KERNEL)?; + + for (i, value) in TEST_VALUES.into_iter().enumerate() { + kernel::dma_write!(ca, [try: i], MyStruct::new(value.0, value.1)); + } + + let size = 4 * page::PAGE_SIZE; + let pages = VVec::with_capacity(size, GFP_KERNEL)?; + + let sgt = SGTable::new(pdev.as_ref(), pages, DataDirection::ToDevice, GFP_KERNEL); + + Ok(try_pin_init!(Self { + pdev: pdev.into(), + ca, + sgt <- sgt, + })) + }) + } +} + +impl DmaSampleDriver { + fn check_dma(&self) { + for (i, value) in TEST_VALUES.into_iter().enumerate() { + let val0 = kernel::dma_read!(self.ca, [panic: i].h); + let val1 = kernel::dma_read!(self.ca, [panic: i].b); + + assert_eq!(val0, value.0); + assert_eq!(val1, value.1); + } + } +} + +#[pinned_drop] +impl PinnedDrop for DmaSampleDriver { + fn drop(self: Pin<&mut Self>) { + dev_info!(self.pdev, "Unload DMA test driver.\n"); + + self.check_dma(); + + for (i, entry) in self.sgt.iter().enumerate() { + dev_info!( + self.pdev, + "Entry[{}]: DMA address: {:#x}", + i, + entry.dma_address(), + ); + } + } +} + +kernel::module_pci_driver! { + type: DmaSampleDriver, + name: "rust_dma", + authors: ["Abdiel Janulgue"], + description: "Rust DMA test", + license: "GPL v2", +} -- cgit v1.3.1