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Wysocki" , Sami Tolvanen Cc: linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, Matthew Maurer Content-Type: text/plain; charset="utf-8" Provides an example of using the Rust DebugFS bindings. Signed-off-by: Matthew Maurer --- MAINTAINERS | 1 + samples/rust/Kconfig | 11 ++++ samples/rust/Makefile | 1 + samples/rust/rust_debugfs.rs | 120 +++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 133 insertions(+) diff --git a/MAINTAINERS b/MAINTAINERS index a3b835e427b083a4ddd690d9e7739851f0af47ae..426bcdac025134e20911de8e2cf5c9efb0591814 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -7278,6 +7278,7 @@ F: rust/kernel/devres.rs F: rust/kernel/driver.rs F: rust/kernel/faux.rs F: rust/kernel/platform.rs +F: samples/rust/rust_debugfs.rs F: samples/rust/rust_driver_platform.rs F: samples/rust/rust_driver_faux.rs diff --git a/samples/rust/Kconfig b/samples/rust/Kconfig index 43cb72d72631bb2d6e06185e1d88778edff6ee13..6c42ed73f842cda26256039e6917bb443738d3f1 100644 --- a/samples/rust/Kconfig +++ b/samples/rust/Kconfig @@ -51,6 +51,17 @@ config SAMPLE_RUST_DMA If unsure, say N. +config SAMPLE_RUST_DEBUGFS + tristate "DebugFS Test Driver" + depends on DEBUG_FS + help + This option builds the Rust DebugFS Test driver sample. + + To compile this as a module, choose M here: + the module will be called rust_debugfs. + + If unsure, say N. + config SAMPLE_RUST_DRIVER_PCI tristate "PCI Driver" depends on PCI diff --git a/samples/rust/Makefile b/samples/rust/Makefile index 6a466afd2a21eba84a3b7b2be29f25dce44e9053..b1fc4677ed53fcf7d0f5a3dbf322f65851bc1784 100644 --- a/samples/rust/Makefile +++ b/samples/rust/Makefile @@ -4,6 +4,7 @@ ccflags-y += -I$(src) # needed for trace events obj-$(CONFIG_SAMPLE_RUST_MINIMAL) += rust_minimal.o obj-$(CONFIG_SAMPLE_RUST_MISC_DEVICE) += rust_misc_device.o obj-$(CONFIG_SAMPLE_RUST_PRINT) += rust_print.o +obj-$(CONFIG_SAMPLE_RUST_DEBUGFS) += rust_debugfs.o obj-$(CONFIG_SAMPLE_RUST_DMA) += rust_dma.o obj-$(CONFIG_SAMPLE_RUST_DRIVER_PCI) += rust_driver_pci.o obj-$(CONFIG_SAMPLE_RUST_DRIVER_PLATFORM) += rust_driver_platform.o diff --git a/samples/rust/rust_debugfs.rs b/samples/rust/rust_debugfs.rs new file mode 100644 index 0000000000000000000000000000000000000000..3fd25848f2d096b03fa70679103bd725d0e42fcf --- /dev/null +++ b/samples/rust/rust_debugfs.rs @@ -0,0 +1,120 @@ +// SPDX-License-Identifier: GPL-2.0 + +// Copyright (C) 2025 Google LLC. + +//! Sample DebugFS exporting module + +use core::fmt; +use core::fmt::{Display, Formatter}; +use core::sync::atomic::{AtomicU32, Ordering}; +use kernel::c_str; +use kernel::debugfs::{Builder, Dir, Values}; +use kernel::debugfs_fmt_file; +use kernel::new_mutex; +use kernel::prelude::*; +use kernel::sync::{Arc, Mutex}; + +module! { + type: RustDebugFs, + name: "rust_debugfs", + authors: ["Matthew Maurer"], + description: "Rust DebugFS usage sample", + license: "GPL", +} + +struct RustDebugFs { + _debugfs: Pin>>, +} + +struct Composite { + major: u32, + minor: u32, +} + +impl Display for Composite { + fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result { + write!(f, "{}.{}", self.major, self.minor) + } +} + +struct Record { + name: &'static CStr, + size: usize, + stride: usize, +} + +struct Backing { + simple: u32, + composite: Composite, + custom: u32, + many: KVec, + atomic: AtomicU32, + locked: Arc>, +} + +impl Backing { + fn new() -> Result { + let mut many = KVec::new(); + many.push( + Record { + name: c_str!("foo"), + size: 1, + stride: 2, + }, + GFP_KERNEL, + )?; + many.push( + Record { + name: c_str!("bar"), + size: 3, + stride: 4, + }, + GFP_KERNEL, + )?; + Ok(Self { + simple: 10, + composite: Composite { major: 1, minor: 2 }, + custom: 37, + many, + atomic: AtomicU32::new(7), + locked: Arc::pin_init(new_mutex!(0), GFP_KERNEL)?, + }) + } + fn build<'a>(&'a self, builder: Builder<'a>) -> Result<()> { + builder.display_file(c_str!("simple"), &self.simple)?; + builder.display_file(c_str!("composite"), &self.composite)?; + debugfs_fmt_file!( + builder, + c_str!("custom"), + &self.custom, + "Foo! {:#010x} Bar!\n" + )?; + for record in self.many.iter() { + let dir = builder.dir(record.name)?; + dir.display_file(c_str!("size"), &record.size)?; + dir.display_file(c_str!("stride"), &record.stride)?; + } + builder.fmt_file(c_str!("atomic"), &self.atomic, &|atomic, f| { + write!(f, "{}\n", atomic.load(Ordering::Relaxed)) + })?; + builder.fmt_file(c_str!("locked"), &self.locked, &|locked, f| { + write!(f, "{}\n", *locked.lock()) + })?; + Ok(()) + } +} + +impl kernel::Module for RustDebugFs { + fn init(_this: &'static ThisModule) -> Result { + let dir = Dir::new(c_str!("sample_debugfs"), None)?; + let backing = Backing::new()?; + let locked = backing.locked.clone(); + let debugfs = KBox::pin_init(Values::attach(backing, dir), GFP_KERNEL)?; + debugfs.as_ref().build(Backing::build)?; + // These mutations could occur at any time in the future, and would remain visible through + // debugfs. + debugfs.as_ref().atomic.store(8, Ordering::Relaxed); + *locked.lock() = 42; + Ok(Self { _debugfs: debugfs }) + } +} -- 2.49.0.901.g37484f566f-goog