[PATCH v3 3/4] rust: configfs: add a sample demonstrating configfs usage

From: Andreas Hindborg
Date: Tue Feb 18 2025 - 08:02:18 EST


Add a sample to the samples folder, demonstrating the intended use of the
rust configfs API.

Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxx>
---
samples/rust/Kconfig | 11 +++
samples/rust/Makefile | 1 +
samples/rust/rust_configfs.rs | 179 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 191 insertions(+)

diff --git a/samples/rust/Kconfig b/samples/rust/Kconfig
index 918dbead2c0b4..2f97bf9a7b4cc 100644
--- a/samples/rust/Kconfig
+++ b/samples/rust/Kconfig
@@ -10,6 +10,17 @@ menuconfig SAMPLES_RUST

if SAMPLES_RUST

+config SAMPLE_RUST_CONFIGFS
+ tristate "Configfs sample"
+ depends on CONFIGFS_FS
+ help
+ This option builds the Rust configfs sample.
+
+ To compile this as a module, choose M here:
+ the module will be called rust_configfs.
+
+ If unsure, say N.
+
config SAMPLE_RUST_MINIMAL
tristate "Minimal"
help
diff --git a/samples/rust/Makefile b/samples/rust/Makefile
index 5a8ab0df0567c..72122f010cafc 100644
--- a/samples/rust/Makefile
+++ b/samples/rust/Makefile
@@ -6,6 +6,7 @@ obj-$(CONFIG_SAMPLE_RUST_MISC_DEVICE) += rust_misc_device.o
obj-$(CONFIG_SAMPLE_RUST_PRINT) += rust_print.o
obj-$(CONFIG_SAMPLE_RUST_DRIVER_PCI) += rust_driver_pci.o
obj-$(CONFIG_SAMPLE_RUST_DRIVER_PLATFORM) += rust_driver_platform.o
+obj-$(CONFIG_SAMPLE_RUST_CONFIGFS) += rust_configfs.o

rust_print-y := rust_print_main.o rust_print_events.o

diff --git a/samples/rust/rust_configfs.rs b/samples/rust/rust_configfs.rs
new file mode 100644
index 0000000000000..36a2c848a979a
--- /dev/null
+++ b/samples/rust/rust_configfs.rs
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Rust configfs sample.
+
+use kernel::alloc::flags;
+use kernel::c_str;
+use kernel::configfs;
+use kernel::configfs_attrs;
+use kernel::new_mutex;
+use kernel::page::PAGE_SIZE;
+use kernel::prelude::*;
+use kernel::sync::Mutex;
+
+module! {
+ type: RustConfigfs,
+ name: "rust_configfs",
+ author: "Rust for Linux Contributors",
+ description: "Rust configfs sample",
+ license: "GPL",
+}
+
+#[pin_data]
+struct RustConfigfs {
+ #[pin]
+ config: configfs::Subsystem<Configuration>,
+}
+
+#[pin_data]
+struct Configuration {
+ message: &'static CStr,
+ #[pin]
+ bar: Mutex<(KBox<[u8; PAGE_SIZE]>, usize)>,
+}
+
+impl Configuration {
+ fn new() -> impl PinInit<Self, Error> {
+ try_pin_init!(Self {
+ message: c_str!("Hello World\n"),
+ bar <- new_mutex!((KBox::new([0; PAGE_SIZE], flags::GFP_KERNEL)?, 0)),
+ })
+ }
+}
+
+impl kernel::InPlaceModule for RustConfigfs {
+ fn init(_module: &'static ThisModule) -> impl PinInit<Self, Error> {
+ pr_info!("Rust configfs sample (init)\n");
+
+ let item_type = configfs_attrs! {
+ container: configfs::Subsystem<Configuration>,
+ data: Configuration,
+ child: Child,
+ attributes: [
+ message: 0,
+ bar: 1,
+ ],
+ };
+
+ try_pin_init!(Self {
+ config <- configfs::Subsystem::new(
+ c_str!("rust_configfs"), item_type, Configuration::new()
+ ),
+ })
+ }
+}
+
+#[vtable]
+impl configfs::GroupOperations for Configuration {
+ type Child = Child;
+
+ fn make_group(&self, name: &CStr) -> Result<impl PinInit<configfs::Group<Child>, Error>> {
+ let tpe = configfs_attrs! {
+ container: configfs::Group<Child>,
+ data: Child,
+ child: GrandChild,
+ attributes: [
+ baz: 0,
+ ],
+ };
+
+ Ok(configfs::Group::new(name.try_into()?, tpe, Child::new()))
+ }
+}
+
+#[vtable]
+impl configfs::AttributeOperations<0> for Configuration {
+ type Data = Configuration;
+
+ fn show(container: &Configuration, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+ pr_info!("Show message\n");
+ let data = container.message;
+ page[0..data.len()].copy_from_slice(data);
+ Ok(data.len())
+ }
+}
+
+#[vtable]
+impl configfs::AttributeOperations<1> for Configuration {
+ type Data = Configuration;
+
+ fn show(container: &Configuration, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+ pr_info!("Show bar\n");
+ let guard = container.bar.lock();
+ let data = guard.0.as_slice();
+ let len = guard.1;
+ page[0..len].copy_from_slice(&data[0..len]);
+ Ok(len)
+ }
+
+ fn store(container: &Configuration, page: &[u8]) -> Result {
+ pr_info!("Store bar\n");
+ let mut guard = container.bar.lock();
+ guard.0[0..page.len()].copy_from_slice(page);
+ guard.1 = page.len();
+ Ok(())
+ }
+}
+
+#[pin_data]
+struct Child {}
+
+impl Child {
+ fn new() -> impl PinInit<Self, Error> {
+ try_pin_init!(Self {})
+ }
+}
+
+#[vtable]
+impl configfs::GroupOperations for Child {
+ type Child = GrandChild;
+
+ fn make_group(&self, name: &CStr) -> Result<impl PinInit<configfs::Group<GrandChild>, Error>> {
+ let tpe = configfs_attrs! {
+ container: configfs::Group<GrandChild>,
+ data: GrandChild,
+ attributes: [
+ gc: 0,
+ ],
+ };
+
+ Ok(configfs::Group::new(
+ name.try_into()?,
+ tpe,
+ GrandChild::new(),
+ ))
+ }
+}
+
+#[vtable]
+impl configfs::AttributeOperations<0> for Child {
+ type Data = Child;
+
+ fn show(_container: &Child, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+ pr_info!("Show baz\n");
+ let data = c"Hello Baz\n".to_bytes();
+ page[0..data.len()].copy_from_slice(data);
+ Ok(data.len())
+ }
+}
+
+#[pin_data]
+struct GrandChild {}
+
+impl GrandChild {
+ fn new() -> impl PinInit<Self, Error> {
+ try_pin_init!(Self {})
+ }
+}
+
+#[vtable]
+impl configfs::AttributeOperations<0> for GrandChild {
+ type Data = GrandChild;
+
+ fn show(_container: &GrandChild, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+ pr_info!("Show baz\n");
+ let data = c"Hello GC\n".to_bytes();
+ page[0..data.len()].copy_from_slice(data);
+ Ok(data.len())
+ }
+}

--
2.47.0