[PATCH linux] of: resolves TODO for copy_from_slice

[PATCH linux] of: resolves TODO for copy_from_slice

[~_xllx_]

From: elle <elle@weathered-steel.dev>

Replaces the copy loop with `copy_from_slice` which became `const` in
stable Rust with version `1.87.0`.

Authored-by: elle <elle@weathered-steel.dev>
Signed-off-by: elle <elle@weathered-steel.dev>
---
 rust/kernel/of.rs | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/rust/kernel/of.rs b/rust/kernel/of.rs
index b76b35265df2..6a5d27b741c6 100644
--- a/rust/kernel/of.rs
+++ b/rust/kernel/of.rs
@@ -39,12 +39,7 @@ impl DeviceId {
         // SAFETY: FFI type is valid to be zero-initialized.
         let mut of: bindings::of_device_id = unsafe { core::mem::zeroed() };
 
-        // TODO: Use `copy_from_slice` once stabilized for `const`.
-        let mut i = 0;
-        while i < src.len() {
-            of.compatible[i] = src[i];
-            i += 1;
-        }
+        of.compatible.copy_from_slice(src);
 
         Self(of)
     }
-- 
2.49.1

Re: [PATCH linux] of: resolves TODO for copy_from_slice

[Greg KH]

On Sun, Aug 10, 2025 at 11:23:55PM +0000, ~_xllx_ wrote:
> From: elle <elle@weathered-steel.dev>
> 
> Replaces the copy loop with `copy_from_slice` which became `const` in
> stable Rust with version `1.87.0`.
> 
> Authored-by: elle <elle@weathered-steel.dev>

This isn't a normal kernel tag, the "From:" line guarantes this, please
no need to repeat it again.

Also, we need a full name please, as per our documentation.

thanks,

greg k-h

Re: [PATCH linux] of: resolves TODO for copy_from_slice

[Elle]

I'll clean this up in future patches, thanks for letting me know.




On Monday, August 11th, 2025 at 7:13 AM, Greg KH <gregkh@linuxfoundation.org> wrote:

> 
> 
> On Sun, Aug 10, 2025 at 11:23:55PM +0000, ~xllx wrote:
> 
> > From: elle elle@weathered-steel.dev
> > 
> > Replaces the copy loop with `copy_from_slice` which became `const` in
> > stable Rust with version `1.87.0`.
> > 
> > Authored-by: elle elle@weathered-steel.dev
> 
> 
> This isn't a normal kernel tag, the "From:" line guarantes this, please
> no need to repeat it again.
> 
> Also, we need a full name please, as per our documentation.
> 
> thanks,
> 
> greg k-h

Re: [PATCH linux] of: resolves TODO for copy_from_slice

[Alice Ryhl]

On Mon, Aug 11, 2025 at 8:38 AM ~_xllx_ <_xllx_@git.sr.ht> wrote:
>
> From: elle <elle@weathered-steel.dev>
>
> Replaces the copy loop with `copy_from_slice` which became `const` in
> stable Rust with version `1.87.0`.
>
> Authored-by: elle <elle@weathered-steel.dev>
> Signed-off-by: elle <elle@weathered-steel.dev>

We still support rustc 1.78 and forward.

Alice

Re: [PATCH linux] of: resolves TODO for copy_from_slice

[Elle]

I tried to find the MSRV before sending the patch, sorry for the noise.

Since this is a pretty low-priority patch, guess it can just hang out until the MSRV bump to 1.87.x?




On Monday, August 11th, 2025 at 8:02 AM, Alice Ryhl <aliceryhl@google.com> wrote:

> 
> 
> On Mon, Aug 11, 2025 at 8:38 AM ~xllx _xllx_@git.sr.ht wrote:
> 
> > From: elle elle@weathered-steel.dev
> > 
> > Replaces the copy loop with `copy_from_slice` which became `const` in
> > stable Rust with version `1.87.0`.
> > 
> > Authored-by: elle elle@weathered-steel.dev
> > Signed-off-by: elle elle@weathered-steel.dev
> 
> 
> We still support rustc 1.78 and forward.
> 
> Alice

Re: [PATCH linux] of: resolves TODO for copy_from_slice

[Miguel Ojeda]

On Mon, Aug 11, 2025 at 10:52 AM Elle <elle@weathered-steel.dev> wrote:
>
> I tried to find the MSRV before sending the patch, sorry for the noise.
>
> Since this is a pretty low-priority patch, guess it can just hang out until the MSRV bump to 1.87.x?

Yes, but that will likely take more than a year, so we will forget
about it, or the code may change anyway.

The other option is using the unstable feature, if it is really useful
etc., but for that we also need to wait until 1.85.0, since that is
where `const_copy_from_slice` was available. Luckily, 1.85.0 is
possibly our next minimum, due to Debian Trixie.

Thanks!

(By the way, please try to avoid top-posting on the mailing list:
https://docs.kernel.org/process/submitting-patches.html#use-trimmed-interleaved-replies-in-email-discussions
:)

Cheers,
Miguel

Re: [PATCH linux] of: resolves TODO for copy_from_slice

[kernel test robot]

Hi ~_xllx_,

kernel test robot noticed the following build errors:

[auto build test ERROR on linux/master]

url:    https://github.com/intel-lab-lkp/linux/commits/_xllx_/of-resolves-TODO-for-copy_from_slice/20250811-144924
base:   linux/master
patch link:    https://lore.kernel.org/r/175489428990.9320.6825335165759789458-0%40git.sr.ht
patch subject: [PATCH linux] of: resolves TODO for copy_from_slice
config: x86_64-rhel-9.4-rust (https://download.01.org/0day-ci/archive/20250812/202508121650.l7ZSniGd-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
rustc: rustc 1.88.0 (6b00bc388 2025-06-23)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250812/202508121650.l7ZSniGd-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202508121650.l7ZSniGd-lkp@intel.com/

All errors (new ones prefixed by >>):

>> error[E0080]: evaluation of constant value failed
   --> rust/doctests_kernel_generated.rs:6978:11
   |
   6978 |          (of::DeviceId::new(c_str!("test,device")), ())
   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation panicked: copy_from_slice: source slice length does not match destination slice length
   |
   note: inside `rust_doctest_kernel_alloc_kbox_rs_7::kernel::of::DeviceId::new`
   --> rust/kernel/of.rs:42:9
   |
   42   |         of.compatible.copy_from_slice(src);
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the failure occurred here
--
>> error[E0080]: evaluation of constant value failed
   --> samples/rust/rust_driver_platform.rs:88:7
   |
   88 |     [(of::DeviceId::new(c_str!("test,rust-device")), Info(42))]
   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation panicked: copy_from_slice: source slice length does not match destination slice length
   |
   note: inside `kernel::of::DeviceId::new`
   --> rust/kernel/of.rs:42:9
   |
   42 |         of.compatible.copy_from_slice(src);
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the failure occurred here

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki