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rust: miscdevice: access file in fops

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This allows fops to access information about the underlying struct file
for the miscdevice. For example, the Binder driver needs to inspect the
O_NONBLOCK flag inside the fops->ioctl() hook.

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Lee Jones <lee@kernel.org>
Tested-by: Lee Jones <lee@kernel.org>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20241210-miscdevice-file-param-v3-1-b2a79b666dc5@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alice Ryhl 2024-12-10 09:39:00 +00:00 committed by Greg Kroah-Hartman
parent 78d4f34e21
commit 0d8a7c7bf4
1 changed files with 25 additions and 6 deletions
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31
rust/kernel/miscdevice.rs
View File

@ -11,6 +11,7 @@
use crate::{
bindings,
error::{to_result, Error, Result, VTABLE_DEFAULT_ERROR},
fs::File,
prelude::*,
str::CStr,
types::{ForeignOwnable, Opaque},
@ -103,10 +104,10 @@ pub trait MiscDevice {
/// Called when the misc device is opened.
///
/// The returned pointer will be stored as the private data for the file.
fn open() -> Result<Self::Ptr>;
fn open(_file: &File) -> Result<Self::Ptr>;
/// Called when the misc device is released.
fn release(device: Self::Ptr) {
fn release(device: Self::Ptr, _file: &File) {
drop(device);
}
@ -117,6 +118,7 @@ pub trait MiscDevice {
/// [`kernel::ioctl`]: mod@crate::ioctl
fn ioctl(
_device: <Self::Ptr as ForeignOwnable>::Borrowed<'_>,
_file: &File,
_cmd: u32,
_arg: usize,
) -> Result<isize> {
@ -133,6 +135,7 @@ pub trait MiscDevice {
#[cfg(CONFIG_COMPAT)]
fn compat_ioctl(
_device: <Self::Ptr as ForeignOwnable>::Borrowed<'_>,
_file: &File,
_cmd: u32,
_arg: usize,
) -> Result<isize> {
@ -187,7 +190,10 @@ unsafe extern "C" fn fops_open<T: MiscDevice>(
return ret;
}
let ptr = match T::open() {
// SAFETY:
// * The file is valid for the duration of this call.
// * There is no active fdget_pos region on the file on this thread.
let ptr = match T::open(unsafe { File::from_raw_file(file) }) {
Ok(ptr) => ptr,
Err(err) => return err.to_errno(),
};
@ -211,7 +217,10 @@ unsafe extern "C" fn fops_release<T: MiscDevice>(
// SAFETY: The release call of a file owns the private data.
let ptr = unsafe { <T::Ptr as ForeignOwnable>::from_foreign(private) };
T::release(ptr);
// SAFETY:
// * The file is valid for the duration of this call.
// * There is no active fdget_pos region on the file on this thread.
T::release(ptr, unsafe { File::from_raw_file(file) });
0
}
@ -229,7 +238,12 @@ unsafe extern "C" fn fops_ioctl<T: MiscDevice>(
// SAFETY: Ioctl calls can borrow the private data of the file.
let device = unsafe { <T::Ptr as ForeignOwnable>::borrow(private) };
match T::ioctl(device, cmd, arg as usize) {
// SAFETY:
// * The file is valid for the duration of this call.
// * There is no active fdget_pos region on the file on this thread.
let file = unsafe { File::from_raw_file(file) };
match T::ioctl(device, file, cmd, arg as usize) {
Ok(ret) => ret as c_long,
Err(err) => err.to_errno() as c_long,
}
@ -249,7 +263,12 @@ unsafe extern "C" fn fops_compat_ioctl<T: MiscDevice>(
// SAFETY: Ioctl calls can borrow the private data of the file.
let device = unsafe { <T::Ptr as ForeignOwnable>::borrow(private) };
match T::compat_ioctl(device, cmd, arg as usize) {
// SAFETY:
// * The file is valid for the duration of this call.
// * There is no active fdget_pos region on the file on this thread.
let file = unsafe { File::from_raw_file(file) };
match T::compat_ioctl(device, file, cmd, arg as usize) {
Ok(ret) => ret as c_long,
Err(err) => err.to_errno() as c_long,
}