Commit 0d8a7c7b authored by Alice Ryhl's avatar Alice Ryhl Committed by Greg Kroah-Hartman
Browse files

rust: miscdevice: access file in fops 



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: default avatarAlice Ryhl <aliceryhl@google.com>
Reviewed-by: default avatarLee Jones <lee@kernel.org>
Tested-by: default avatarLee Jones <lee@kernel.org>
Reviewed-by: default avatarDanilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20241210-miscdevice-file-param-v3-1-b2a79b666dc5@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 78d4f34e

rust/kernel/miscdevice.rs

+25 −6
Original line number Diff line number Diff line
@@ -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 @@ fn release(device: Self::Ptr) { 
    /// [`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 @@ fn ioctl( 
    #[cfg(CONFIG_COMPAT)]

    fn compat_ioctl(

        _device: <Self::Ptr as ForeignOwnable>::Borrowed<'_>,

        _file: &File,

        _cmd: u32,

        _arg: usize,

    ) -> Result<isize> {
@@ -187,7 +190,10 @@ impl<T: MiscDevice> VtableHelper<T> { 
        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 @@ impl<T: MiscDevice> VtableHelper<T> { 
    // 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 @@ impl<T: MiscDevice> VtableHelper<T> { 
    // 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 @@ impl<T: MiscDevice> VtableHelper<T> { 
    // 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,

    }