FAILED: patch "[PATCH] rust: kbuild: give `--config-path` to `rustfmt` in `.rsi`" failed to apply to 6.1-stable tree

FAILED: patch "[PATCH] rust: kbuild: give `--config-path` to `rustfmt` in `.rsi`" failed to apply to 6.1-stable tree

[gregkh]

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x af20ae33e7dd949f2e770198e74ac8f058cb299d
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026020314-retool-immobile-ceeb@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From af20ae33e7dd949f2e770198e74ac8f058cb299d Mon Sep 17 00:00:00 2001
From: Miguel Ojeda <ojeda@kernel.org>
Date: Thu, 15 Jan 2026 19:38:32 +0100
Subject: [PATCH] rust: kbuild: give `--config-path` to `rustfmt` in `.rsi`
 target

`rustfmt` is configured via the `.rustfmt.toml` file in the source tree,
and we apply `rustfmt` to the macro expanded sources generated by the
`.rsi` target.

However, under an `O=` pointing to an external folder (i.e. not just
a subdir), `rustfmt` will not find the file when checking the parent
folders. Since the edition is configured in this file, this can lead to
errors when it encounters newer syntax, e.g.

    error: expected one of `!`, `.`, `::`, `;`, `?`, `where`, `{`, or an operator, found `"rust_minimal"`
      --> samples/rust/rust_minimal.rsi:29:49
       |
    28 | impl ::kernel::ModuleMetadata for RustMinimal {
       |                                               - while parsing this item list starting here
    29 |     const NAME: &'static ::kernel::str::CStr = c"rust_minimal";
       |                                                 ^^^^^^^^^^^^^^ expected one of 8 possible tokens
    30 | }
       | - the item list ends here
       |
       = note: you may be trying to write a c-string literal
       = note: c-string literals require Rust 2021 or later
       = help: pass `--edition 2024` to `rustc`
       = note: for more on editions, read https://doc.rust-lang.org/edition-guide

A workaround is to use `RUSTFMT=n`, which is documented in the `Makefile`
help for cases where macro expanded source may happen to break `rustfmt`
for other reasons, but this is not one of those cases.

One solution would be to pass `--edition`, but we want `rustfmt` to
use the entire configuration, even if currently we essentially use the
default configuration.

Thus explicitly give the path to the config file to `rustfmt` instead.

Reported-by: Alice Ryhl <aliceryhl@google.com>
Fixes: 2f7ab1267dc9 ("Kbuild: add Rust support")
Cc: stable@vger.kernel.org
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260115183832.46595-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 5037f4715d74..0c838c467c76 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -356,7 +356,7 @@ $(obj)/%.o: $(obj)/%.rs FORCE
 quiet_cmd_rustc_rsi_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
       cmd_rustc_rsi_rs = \
 	$(rust_common_cmd) -Zunpretty=expanded $< >$@; \
-	command -v $(RUSTFMT) >/dev/null && $(RUSTFMT) $@
+	command -v $(RUSTFMT) >/dev/null && $(RUSTFMT) --config-path $(srctree)/.rustfmt.toml $@
 
 $(obj)/%.rsi: $(obj)/%.rs FORCE
 	+$(call if_changed_dep,rustc_rsi_rs)

Re: FAILED: patch "[PATCH] rust: kbuild: give `--config-path` to `rustfmt` in `.rsi`" failed to apply to 6.1-stable tree

[Gary Guo]

On Tue Feb 3, 2026 at 12:44 PM GMT, gregkh wrote:
>
> The patch below does not apply to the 6.1-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

"rsi" target is for development/debugging purpose so I think it's fine to leave
it as is on 6.1 and there shouldn't be a need to create dedicated backport.

Best,
Gary

>
> To reproduce the conflict and resubmit, you may use the following commands:
>
> git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
> git checkout FETCH_HEAD
> git cherry-pick -x af20ae33e7dd949f2e770198e74ac8f058cb299d
> # <resolve conflicts, build, test, etc.>
> git commit -s
> git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026020314-retool-immobile-ceeb@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..
>
> Possible dependencies:
>
>
>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> From af20ae33e7dd949f2e770198e74ac8f058cb299d Mon Sep 17 00:00:00 2001
> From: Miguel Ojeda <ojeda@kernel.org>
> Date: Thu, 15 Jan 2026 19:38:32 +0100
> Subject: [PATCH] rust: kbuild: give `--config-path` to `rustfmt` in `.rsi`
>  target
>
> `rustfmt` is configured via the `.rustfmt.toml` file in the source tree,
> and we apply `rustfmt` to the macro expanded sources generated by the
> `.rsi` target.
>
> However, under an `O=` pointing to an external folder (i.e. not just
> a subdir), `rustfmt` will not find the file when checking the parent
> folders. Since the edition is configured in this file, this can lead to
> errors when it encounters newer syntax, e.g.
>
>     error: expected one of `!`, `.`, `::`, `;`, `?`, `where`, `{`, or an operator, found `"rust_minimal"`
>       --> samples/rust/rust_minimal.rsi:29:49
>        |
>     28 | impl ::kernel::ModuleMetadata for RustMinimal {
>        |                                               - while parsing this item list starting here
>     29 |     const NAME: &'static ::kernel::str::CStr = c"rust_minimal";
>        |                                                 ^^^^^^^^^^^^^^ expected one of 8 possible tokens
>     30 | }
>        | - the item list ends here
>        |
>        = note: you may be trying to write a c-string literal
>        = note: c-string literals require Rust 2021 or later
>        = help: pass `--edition 2024` to `rustc`
>        = note: for more on editions, read https://doc.rust-lang.org/edition-guide
>
> A workaround is to use `RUSTFMT=n`, which is documented in the `Makefile`
> help for cases where macro expanded source may happen to break `rustfmt`
> for other reasons, but this is not one of those cases.
>
> One solution would be to pass `--edition`, but we want `rustfmt` to
> use the entire configuration, even if currently we essentially use the
> default configuration.
>
> Thus explicitly give the path to the config file to `rustfmt` instead.
>
> Reported-by: Alice Ryhl <aliceryhl@google.com>
> Fixes: 2f7ab1267dc9 ("Kbuild: add Rust support")
> Cc: stable@vger.kernel.org
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> Reviewed-by: Gary Guo <gary@garyguo.net>
> Link: https://patch.msgid.link/20260115183832.46595-1-ojeda@kernel.org
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
>
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 5037f4715d74..0c838c467c76 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -356,7 +356,7 @@ $(obj)/%.o: $(obj)/%.rs FORCE
>  quiet_cmd_rustc_rsi_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
>        cmd_rustc_rsi_rs = \
>  	$(rust_common_cmd) -Zunpretty=expanded $< >$@; \
> -	command -v $(RUSTFMT) >/dev/null && $(RUSTFMT) $@
> +	command -v $(RUSTFMT) >/dev/null && $(RUSTFMT) --config-path $(srctree)/.rustfmt.toml $@
>  
>  $(obj)/%.rsi: $(obj)/%.rs FORCE
>  	+$(call if_changed_dep,rustc_rsi_rs)