Normalize semaphore samples and add them to the CI

.github/workflows/ci.yaml

@@ -301,6 +301,14 @@ jobs:
           grep '] rust_stack_probing: Rust stack probing sample (init)$' qemu-stdout.log
           grep '] rust_stack_probing: Rust stack probing sample (exit)$' qemu-stdout.log
 
+      - run: |
+          grep '] rust_semaphore: Rust semaphore sample (init)$' qemu-stdout.log
+          grep '] rust_semaphore: Rust semaphore sample (exit)$' qemu-stdout.log
+
+      - run: |
+          grep '] rust_semaphore_c: Rust semaphore sample (in C, for comparison) (init)$' qemu-stdout.log
+          grep '] rust_semaphore_c: Rust semaphore sample (in C, for comparison) (exit)$' qemu-stdout.log
+
       # Report
       - run: |
           ls -l \

.github/workflows/kernel-arm64-debug.config

@@ -1427,6 +1427,8 @@ CONFIG_SAMPLE_RUST_SYNC=m
 CONFIG_SAMPLE_RUST_CHRDEV=m
 CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
+CONFIG_SAMPLE_RUST_SEMAPHORE=m
+CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 
 #
 # arm64 Debugging

.github/workflows/kernel-arm64-release.config

@@ -1345,6 +1345,8 @@ CONFIG_SAMPLE_RUST_SYNC=m
 CONFIG_SAMPLE_RUST_CHRDEV=m
 CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
+CONFIG_SAMPLE_RUST_SEMAPHORE=m
+CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 
 #
 # arm64 Debugging

.github/workflows/kernel-ppc64le-debug.config

@@ -1487,6 +1487,8 @@ CONFIG_SAMPLE_RUST_SYNC=m
 CONFIG_SAMPLE_RUST_CHRDEV=m
 CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
+CONFIG_SAMPLE_RUST_SEMAPHORE=m
+CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 CONFIG_ARCH_HAS_DEVMEM_IS_ALLOWED=y
 # CONFIG_STRICT_DEVMEM is not set
 

.github/workflows/kernel-ppc64le-release.config

@@ -1449,6 +1449,8 @@ CONFIG_SAMPLE_RUST_SYNC=m
 CONFIG_SAMPLE_RUST_CHRDEV=m
 CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
+CONFIG_SAMPLE_RUST_SEMAPHORE=m
+CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 CONFIG_ARCH_HAS_DEVMEM_IS_ALLOWED=y
 # CONFIG_STRICT_DEVMEM is not set
 

.github/workflows/kernel-x86_64-debug.config

@@ -1439,6 +1439,8 @@ CONFIG_SAMPLE_RUST_SYNC=m
 CONFIG_SAMPLE_RUST_CHRDEV=m
 CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
+CONFIG_SAMPLE_RUST_SEMAPHORE=m
+CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 CONFIG_ARCH_HAS_DEVMEM_IS_ALLOWED=y
 # CONFIG_STRICT_DEVMEM is not set
 

.github/workflows/kernel-x86_64-release.config

@@ -1387,6 +1387,8 @@ CONFIG_SAMPLE_RUST_SYNC=m
 CONFIG_SAMPLE_RUST_CHRDEV=m
 CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
+CONFIG_SAMPLE_RUST_SEMAPHORE=m
+CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 CONFIG_ARCH_HAS_DEVMEM_IS_ALLOWED=y
 # CONFIG_STRICT_DEVMEM is not set
 

.github/workflows/qemu-init.sh

@@ -21,6 +21,12 @@ busybox  rmmod rust_miscdev.ko
 busybox insmod rust_stack_probing.ko
 busybox  rmmod rust_stack_probing.ko
 
+busybox insmod rust_semaphore.ko
+busybox  rmmod rust_semaphore.ko
+
+busybox insmod rust_semaphore_c.ko
+busybox  rmmod rust_semaphore_c.ko
+
 busybox insmod rust_module_parameters_loadable_default.ko
 busybox insmod rust_module_parameters_loadable_custom.ko \
     my_bool=n \

.github/workflows/qemu-initramfs.desc

@@ -12,6 +12,8 @@ file    /rust_sync.ko               samples/rust/rust_sync.ko               0755
 file    /rust_chrdev.ko             samples/rust/rust_chrdev.ko             0755 0 0
 file    /rust_miscdev.ko            samples/rust/rust_miscdev.ko            0755 0 0
 file    /rust_stack_probing.ko      samples/rust/rust_stack_probing.ko      0755 0 0
+file    /rust_semaphore.ko          samples/rust/rust_semaphore.ko          0755 0 0
+file    /rust_semaphore_c.ko        samples/rust/rust_semaphore_c.ko        0755 0 0
 
 file    /rust_module_parameters_loadable_default.ko  samples/rust/rust_module_parameters_loadable_default.ko  0755 0 0
 file    /rust_module_parameters_loadable_custom.ko   samples/rust/rust_module_parameters_loadable_custom.ko   0755 0 0

samples/rust/Kconfig

@@ -80,20 +80,24 @@ config SAMPLE_RUST_STACK_PROBING
 
 	  If unsure, say N.
 
-config SAMPLE_SEMAPHORE
-	tristate "Semaphore in C"
+config SAMPLE_RUST_SEMAPHORE
+	tristate "Semaphore"
 	help
-	  This option builds the C semaphore sample.
+	  This option builds the Rust semaphore sample.
 
 	  To compile this as a module, choose M here:
-	  the module will be called semaphore.
+	  the module will be called rust_semaphore.
 
-config SAMPLE_RUST_SEMAPHORE
-	tristate "Semaphore in Rust"
+	  If unsure, say N.
+
+config SAMPLE_RUST_SEMAPHORE_C
+	tristate "Semaphore (in C, for comparison)"
 	help
-	  This option builds the Rust semaphore sample.
+	  This option builds the Rust semaphore sample (in C, for comparison).
 
 	  To compile this as a module, choose M here:
-	  the module will be called rust_semaphore.
+	  the module will be called rust_semaphore_c.
+
+	  If unsure, say N.
 
 endif # SAMPLES_RUST

samples/rust/Makefile

@@ -7,5 +7,5 @@ obj-$(CONFIG_SAMPLE_RUST_SYNC)			+= rust_sync.o
 obj-$(CONFIG_SAMPLE_RUST_CHRDEV)		+= rust_chrdev.o
 obj-$(CONFIG_SAMPLE_RUST_MISCDEV)		+= rust_miscdev.o
 obj-$(CONFIG_SAMPLE_RUST_STACK_PROBING)		+= rust_stack_probing.o
-obj-$(CONFIG_SAMPLE_SEMAPHORE)			+= semaphore.o
 obj-$(CONFIG_SAMPLE_RUST_SEMAPHORE)		+= rust_semaphore.o
+obj-$(CONFIG_SAMPLE_RUST_SEMAPHORE_C)		+= rust_semaphore_c.o

samples/rust/rust_semaphore.rs

@@ -1,5 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 
+//! Rust semaphore sample
+//!
 //! A counting semaphore that can be used by userspace.
 //!
 //! The count is incremented by writes to the device. A write of `n` bytes results in an increment
@@ -31,10 +33,10 @@ use kernel::{
 };
 
 module! {
-    type: RustSemaphoreModule,
+    type: RustSemaphore,
     name: b"rust_semaphore",
     author: b"Rust for Linux Contributors",
-    description: b"An example kernel module written in Rust",
+    description: b"Rust semaphore sample",
     license: b"GPL v2",
     params: {},
 }
@@ -111,15 +113,18 @@ impl FileOperations for FileState {
     fn release(_obj: Box<Self>, _file: &File) {}
 }
 
-struct RustSemaphoreModule {
+struct RustSemaphore {
     _dev: Pin<Box<Registration<Arc<Semaphore>>>>,
 }
 
-impl KernelModule for RustSemaphoreModule {
+impl KernelModule for RustSemaphore {
     fn init() -> KernelResult<Self> {
+        info!("Rust semaphore sample (init)");
+
         let sema = Arc::try_new(Semaphore {
             // SAFETY: `condvar_init!` is called below.
             changed: unsafe { CondVar::new() },
+
             // SAFETY: `mutex_init!` is called below.
             inner: unsafe {
                 Mutex::new(SemaphoreInner {
@@ -128,16 +133,25 @@ impl KernelModule for RustSemaphoreModule {
                 })
             },
         })?;
+
         // SAFETY: `changed` is pinned behind `Arc`.
         condvar_init!(Pin::new_unchecked(&sema.changed), "Semaphore::changed");
+
         // SAFETY: `inner` is pinned behind `Arc`.
         mutex_init!(Pin::new_unchecked(&sema.inner), "Semaphore::inner");
+
         Ok(Self {
             _dev: Registration::new_pinned::<FileState>(cstr!("rust_semaphore"), None, sema)?,
         })
     }
 }
 
+impl Drop for RustSemaphore {
+    fn drop(&mut self) {
+        info!("Rust semaphore sample (exit)");
+    }
+}
+
 const IOCTL_GET_READ_COUNT: u32 = 0x80086301;
 const IOCTL_SET_READ_COUNT: u32 = 0x40086301;
 

samples/rust/semaphore.c → samples/rust/rust_semaphore_c.c

@@ -1,7 +1,13 @@
 // SPDX-License-Identifier: GPL-2.0
+/*
+ * Rust semaphore sample (in C, for comparison)
+ *
+ * This is a C implementation of `rust_semaphore.rs`. Refer to the description
+ * in that file for details on the device.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
-// This is a C implementation of `rust_semaphore.rs`. Refer to the description
-// in that file for details on the device.
 #include <linux/miscdevice.h>
 #include <linux/module.h>
 #include <linux/fs.h>
@@ -165,6 +171,8 @@ static int __init semaphore_init(void)
 	int ret;
 	struct semaphore_state *state;
 
+	pr_info("Rust semaphore sample (in C, for comparison) (init)\n");
+
 	state = kzalloc(sizeof(*state), GFP_KERNEL);
 	if (!state)
 		return -ENOMEM;
@@ -190,6 +198,8 @@ static int __init semaphore_init(void)
 
 static void __exit semaphore_exit(void)
 {
+	pr_info("Rust semaphore sample (in C, for comparison) (exit)\n");
+
 	misc_deregister(&device->miscdev);
 	kref_put(&device->ref, semaphore_free);
 }
@@ -198,3 +208,5 @@ module_init(semaphore_init);
 module_exit(semaphore_exit);
 
 MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Rust for Linux Contributors");
+MODULE_DESCRIPTION("Rust semaphore sample (in C, for comparison)");