Some println debugging

Author: alex

src/chrdev.rs

@@ -49,6 +49,7 @@ impl DeviceNumberRegion {
         unsafe {
             (*cdev).owner = &mut bindings::__this_module;
             (*cdev).ops = &T::VTABLE.0 as *const bindings::file_operations;
+            crate::println!("vtable={:?}", T::VTABLE.0);
         }
         let cdev = DeviceRegistration {
             cdev,
@@ -93,6 +94,7 @@ unsafe extern "C" fn open_callback<T: FileOperations>(
     _inode: *mut bindings::inode,
     file: *mut bindings::file,
 ) -> c_types::c_int {
+    crate::println!("open_callback reached");
     let f = match T::open() {
         Ok(f) => Box::new(f),
         Err(e) => return e.to_kernel_errno(),
@@ -107,6 +109,7 @@ unsafe extern "C" fn read_callback<T: FileOperations>(
     len: c_types::c_size_t,
     offset: *mut bindings::loff_t,
 ) -> c_types::c_ssize_t {
+    crate::println!("read_callback reached");
     let mut data = match UserSlicePtr::new(buf as *mut c_types::c_void, len) {
         Ok(ptr) => ptr.writer(),
         Err(e) => return e.to_kernel_errno() as c_types::c_ssize_t,
@@ -117,6 +120,7 @@ unsafe extern "C" fn read_callback<T: FileOperations>(
         Ok(()) => {
             let written = len - data.len();
             (*offset) += written as bindings::loff_t;
+            crate::println!("read_callback: written={}", written);
             return written as c_types::c_ssize_t;
         }
         Err(e) => return e.to_kernel_errno() as c_types::c_ssize_t,
@@ -127,6 +131,7 @@ unsafe extern "C" fn release_callback<T: FileOperations>(
     _inode: *mut bindings::inode,
     file: *mut bindings::file,
 ) -> c_types::c_int {
+    crate::println!("release_callback reached");
     let ptr = (*file).private_data as *mut T;
     (*file).private_data = ptr::null_mut();
     Box::from_raw(ptr);

testlib/src/lib.rs

@@ -29,12 +29,12 @@ impl Drop for LoadedModule {
 }
 
 pub fn with_kernel_module<F: Fn()>(f: F) {
-    let status = Command::new("sudo")
-        .arg("dmesg")
-        .arg("-C")
-        .status()
-        .unwrap();
-    assert!(status.success());
+    // let status = Command::new("sudo")
+    //     .arg("dmesg")
+    //     .arg("-C")
+    //     .status()
+    //     .unwrap();
+    // assert!(status.success());
     let _m = LoadedModule::load(env::var("KERNEL_MODULE").unwrap());
     f();
 }

tests/chrdev/src/lib.rs

@@ -21,8 +21,10 @@ impl linux_kernel_module::chrdev::FileOperations for CycleFile {
         &self,
         buf: &mut linux_kernel_module::user_ptr::UserSlicePtrWriter,
     ) -> linux_kernel_module::KernelResult<()> {
+        linux_kernel_module::println!("Called CycleFile::read with buf len: {}", buf.len());
         for c in b"123456789".iter().cycle().take(buf.len()) {
             buf.write(&[*c])?;
+            linux_kernel_module::println!("CycleFile::read: buf.write()")
         }
         return Ok(());
     }
@@ -35,9 +37,11 @@ struct ChrdevTestModule {
 
 impl linux_kernel_module::KernelModule for ChrdevTestModule {
     fn init() -> linux_kernel_module::KernelResult<Self> {
+        linux_kernel_module::println!("Loaded chrdev module!");
         let dev_region =
             linux_kernel_module::chrdev::DeviceNumberRegion::allocate(0..1, "chrdev-tests\x00")?;
         let chrdev_registration = dev_region.register_device::<CycleFile>()?;
+        linux_kernel_module::println!("Almost done!");
         Ok(ChrdevTestModule {
             _dev_region: dev_region,
             _chrdev_registration: chrdev_registration,