Subject: linux-next: manual merge of the rust tree with the driver-core tree

From: Stephen Rothwell <[email-masked]>
Date: Tue, 14 Jan 2025 15:46:23 +1100

Hi all,

Today's linux-next merge of the rust tree got a conflict in:

  rust/kernel/miscdevice.rs

between commit:

  88441d5c6d17 ("rust: miscdevice: access the `struct miscdevice` from fops->open()")

from the driver-core tree and commit:

  14686571a914 ("rust: kernel: change `ForeignOwnable` pointer to mut")

from the rust tree.

I fixed it up (see below) and can carry the fix as necessary. This
is now fixed as far as linux-next is concerned, but any non trivial
conflicts should be mentioned to your upstream maintainer when your tree
is submitted for merging.  You may also want to consider cooperating
with the maintainer of the conflicting tree to minimise any particularly
complex conflicts.

-- 
Cheers,
Stephen Rothwell

diff --cc rust/kernel/miscdevice.rs
index dfb363630c70,b3a6cc50b240..000000000000
--- a/rust/kernel/miscdevice.rs
+++ b/rust/kernel/miscdevice.rs
@@@ -10,11 -10,9 +10,12 @@@
  
  use crate::{
      bindings,
 +    device::Device,
      error::{to_result, Error, Result, VTABLE_DEFAULT_ERROR},
+     ffi::{c_int, c_long, c_uint, c_ulong},
 +    fs::File,
      prelude::*,
 +    seq_file::SeqFile,
      str::CStr,
      types::{ForeignOwnable, Opaque},
  };
@@@ -151,17 -132,8 +147,17 @@@ pub trait MiscDevice: Sized 
          _cmd: u32,
          _arg: usize,
      ) -> Result<isize> {
-         kernel::build_error!(VTABLE_DEFAULT_ERROR)
+         build_error!(VTABLE_DEFAULT_ERROR)
      }
 +
 +    /// Show info for this fd.
 +    fn show_fdinfo(
 +        _device: <Self::Ptr as ForeignOwnable>::Borrowed<'_>,
 +        _m: &SeqFile,
 +        _file: &File,
 +    ) {
-         kernel::build_error!(VTABLE_DEFAULT_ERROR)
++        build_error!(VTABLE_DEFAULT_ERROR)
 +    }
  }
  
  const fn create_vtable<T: MiscDevice>() -> &'static bindings::file_operations {
@@@ -230,12 -188,8 +226,12 @@@ unsafe extern "C" fn fops_open<T: MiscD
          Err(err) => return err.to_errno(),
      };
  
 -    // SAFETY: The open call of a file owns the private data.
 -    unsafe { (*file).private_data = ptr.into_foreign() };
 +    // This overwrites the private data with the value specified by the user, changing the type of
 +    // this file's private data. All future accesses to the private data is performed by other
 +    // fops_* methods in this file, which all correctly cast the private data to the new type.
 +    //
 +    // SAFETY: The open call of a file can access the private data.
-     unsafe { (*raw_file).private_data = ptr.into_foreign().cast_mut() };
++    unsafe { (*raw_file).private_data = ptr.into_foreign() };
  
      0
  }
@@@ -274,12 -225,7 +270,12 @@@ unsafe extern "C" fn fops_ioctl<T: Misc
      // 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) {
 +    // 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) {
++    match T::ioctl(device, file, cmd, arg) {
          Ok(ret) => ret as c_long,
          Err(err) => err.to_errno() as c_long,
      }
@@@ -299,12 -245,7 +295,12 @@@ unsafe extern "C" fn fops_compat_ioctl<
      // 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) {
 +    // 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) {
++    match T::compat_ioctl(device, file, cmd, arg) {
          Ok(ret) => ret as c_long,
          Err(err) => err.to_errno() as c_long,
      }