From ac3b8a6a6ab105cc822824eb5baf2d421fa70b29 Mon Sep 17 00:00:00 2001
From: Wedson Almeida Filho <wedsonaf@google.com>
Date: Thu, 25 Mar 2021 21:56:40 +0000
Subject: [PATCH] Change `read` and `write` to return the number of bytes
read/written.
---
drivers/char/rust_example.rs | 11 +++++------
rust/kernel/file_operations.rs | 23 +++++++++++++----------
2 files changed, 18 insertions(+), 16 deletions(-)
diff --git a/drivers/char/rust_example.rs b/drivers/char/rust_example.rs
index 836e99f6adb027..2c23cb4060a876 100644
--- a/drivers/char/rust_example.rs
+++ b/drivers/char/rust_example.rs
@@ -99,10 +99,10 @@ impl FileOperations for Token {
kernel::declare_file_operations!(read, write);
- fn read(&self, _file: &File, data: &mut UserSlicePtrWriter, offset: u64) -> KernelResult {
+ fn read(&self, _: &File, data: &mut UserSlicePtrWriter, offset: u64) -> KernelResult<usize> {
// Succeed if the caller doesn't provide a buffer or if not at the start.
if data.is_empty() || offset != 0 {
- return Ok(());
+ return Ok(0);
}
{
@@ -124,10 +124,10 @@ impl FileOperations for Token {
// Write a one-byte 1 to the reader.
data.write_slice(&[1u8; 1])?;
- Ok(())
+ Ok(1)
}
- fn write(&self, data: &mut UserSlicePtrReader, _offset: u64) -> KernelResult<isize> {
+ fn write(&self, data: &mut UserSlicePtrReader, _offset: u64) -> KernelResult<usize> {
{
let mut inner = self.shared.inner.lock();
@@ -144,8 +144,7 @@ impl FileOperations for Token {
// Notify a possible reader waiting.
self.shared.state_changed.notify_all();
- data.read_all()?;
- Ok(0)
+ Ok(data.len())
}
}
diff --git a/rust/kernel/file_operations.rs b/rust/kernel/file_operations.rs
index 3c4c076dddca9c..9f7d3f524f003f 100644
--- a/rust/kernel/file_operations.rs
+++ b/rust/kernel/file_operations.rs
@@ -105,10 +105,9 @@ unsafe extern "C" fn read_callback<T: FileOperations>(
let f = &*((*file).private_data as *const T);
// No `FMODE_UNSIGNED_OFFSET` support, so `offset` must be in [0, 2^63).
// See discussion in https://github.com/fishinabarrel/linux-kernel-module-rust/pull/113
- T::read(f, &File::from_ptr(file), &mut data, (*offset).try_into()?)?;
- let written = len - data.len();
- (*offset) += bindings::loff_t::try_from(written).unwrap();
- Ok(written.try_into().unwrap())
+ let read = f.read(&File::from_ptr(file), &mut data, (*offset).try_into()?)?;
+ (*offset) += bindings::loff_t::try_from(read).unwrap();
+ Ok(read as _)
}
}
@@ -123,10 +122,9 @@ unsafe extern "C" fn write_callback<T: FileOperations>(
let f = &*((*file).private_data as *const T);
// No `FMODE_UNSIGNED_OFFSET` support, so `offset` must be in [0, 2^63).
// See discussion in https://github.com/fishinabarrel/linux-kernel-module-rust/pull/113
- T::write(f, &mut data, (*offset).try_into()?)?;
- let read = len - data.len();
- (*offset) += bindings::loff_t::try_from(read).unwrap();
- Ok(read.try_into().unwrap())
+ let written = f.write(&mut data, (*offset).try_into()?)?;
+ (*offset) += bindings::loff_t::try_from(written).unwrap();
+ Ok(written as _)
}
}
@@ -470,14 +468,19 @@ pub trait FileOperations: Send + Sync + Sized {
/// Reads data from this file to userspace.
///
/// Corresponds to the `read` function pointer in `struct file_operations`.
- fn read(&self, _file: &File, _data: &mut UserSlicePtrWriter, _offset: u64) -> KernelResult {
+ fn read(
+ &self,
+ _file: &File,
+ _data: &mut UserSlicePtrWriter,
+ _offset: u64,
+ ) -> KernelResult<usize> {
Err(Error::EINVAL)
}
/// Writes data from userspace to this file.
///
/// Corresponds to the `write` function pointer in `struct file_operations`.
- fn write(&self, _data: &mut UserSlicePtrReader, _offset: u64) -> KernelResult<isize> {
+ fn write(&self, _data: &mut UserSlicePtrReader, _offset: u64) -> KernelResult<usize> {
Err(Error::EINVAL)
}