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

From: Stephen Rothwell <[email-masked]>
Date: Thu, 23 Jan 2025 14:31:39 +1100

Hi all,

On Mon, 13 Jan 2025 15:12:36 +1100 Stephen Rothwell <[email-masked]> wrote:
>
> Today's linux-next merge of the rust tree got a conflict in:
> 
>   rust/kernel/miscdevice.rs
> 
> between commits:
> 
>   0d8a7c7bf47a ("rust: miscdevice: access file in fops")
>   5bcc8bfe841b ("rust: miscdevice: add fops->show_fdinfo() hook")
>   bf2aa7df2687 ("miscdevice: rust: use build_error! macro instead of function")
> 
> from the driver-core tree and commits:
> 
>   27c7518e7f1c ("rust: finish using custom FFI integer types")
>   1bae8729e50a ("rust: map `long` to `isize` and `char` to `u8`")
>   15f2f9313a39 ("rust: use the `build_error!` macro, not the hidden function")
>   4401565fe92b ("rust: add `build_error!` to the prelude")
> 
> 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 dfb363630c70,9e1b9c0fae9d..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 {
> @@@ -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,
>       }

This is now a conflict between the driver-core tree and Linus' tree.

-- 
Cheers,
Stephen Rothwell