[RFC PATCH 0/2] scripts: add kconfirm

[Julian Braha <julianbraha@gmail.com>]

Hi all,

Following this discussion:
https://lore.kernel.org/all/20260405122749.4990dcb538d457769a3276e0@linux-foundation.org/
in which Andrew brought up the possibility of moving kconfirm in-tree,
I've prepared this RFC to do so. See also kconfirm's introduction to the
mailing list:
https://lore.kernel.org/all/6ec4df6d-1445-48ca-8f54-1d1a83c4716d@gmail.com/

kconfirm currently detects dead code (defaults, dependencies, selects, and
ranges), and includes an optional check for dead links in the help texts.

False Alarms:
kconfirm aims for zero false-positives, which is currently true for dead
code detection (as far as I'm aware - but there are hundreds to go 
through); this is not really possible for dead link checks, as this
depends on an internet connection, and we do not attempt to bypass bot
blocks. For this reason, dead link checking is disabled by default, but
I've provided an example of how to enable it. Additionally, you can view
my previous message to the mailing list with hand-verified dead links
here:
https://lore.kernel.org/all/6732bf08-41ee-40c4-83b2-4ae8bc0da7cf@gmail.com/

Current State of Alarms:
The last time I checked linux-next (next-20260427), there were 579
instances of dead code, and 81 unique dead links. The most critical check
is the dead default statements, which has surfaced a few misconfiguration
bugs (fortunately, just for kunit tests), see examples:
https://lore.kernel.org/all/20260323124118.1414913-1-julianbraha@gmail.com/
and:
https://lore.kernel.org/all/20260323123536.1413732-1-julianbraha@gmail.com/

But hopefully kconfirm can ease maintenance and we can prevent more of
these from making it into the tree in the future.

Use it:
You can test out kconfirm with this patch series by compiling and running
kconfirm like this:

`make kconfirm`

You can enable dead link checks in the help texts by
passing KCONFIRM_ARGS="--enable dead_links", like this:

`KCONFIRM_ARGS="--enable dead_links" make kconfirm`

Note that it is not architecture-specific; it runs tree-wide.
If you run it on linux-next, you should find 579 instances of dead code.
Originally this number was even higher, but many patches have since been
applied to linux-next, and included in linux 7.1-rc1. Thank you to the
maintainers and reviewers for their feedback and patience :)

You will need Rust with Cargo and an internet connection to download the
dependencies for compilation. Originally, I planned to vendor the
dependencies and submit the entirety of the code here, in-tree, but the
dependencies (and their dependencies...) are too large (somehow, a
whopping 264MB!), so instead I am proposing to add just the tool's own
code.

I've included the Rust for Linux team to discuss the build system changes,
as I'd like know if there is a better way to integrate this with `make`,
and if there's a better solution as far as the dependencies and Cargo go.

Thanks,
Julian Braha

Julian Braha (2):
  scripts: add kconfirm
  Documentation: dev-tools: add kconfirm

 Documentation/dev-tools/index.rst             |    1 +
 Documentation/dev-tools/kconfirm.rst          |  147 ++
 Makefile                                      |   12 +-
 scripts/Makefile                              |    2 +-
 scripts/kconfirm/Cargo.lock                   | 1710 +++++++++++++++++
 scripts/kconfirm/Cargo.toml                   |   21 +
 scripts/kconfirm/Makefile                     |   28 +
 scripts/kconfirm/kconfirm-lib/Cargo.toml      |   16 +
 scripts/kconfirm/kconfirm-lib/src/analyze.rs  |  593 ++++++
 scripts/kconfirm/kconfirm-lib/src/checks.rs   |  257 +++
 .../kconfirm/kconfirm-lib/src/dead_links.rs   |   63 +
 scripts/kconfirm/kconfirm-lib/src/lib.rs      |   55 +
 scripts/kconfirm/kconfirm-lib/src/output.rs   |   52 +
 .../kconfirm/kconfirm-lib/src/symbol_table.rs |  209 ++
 scripts/kconfirm/kconfirm-linux/Cargo.toml    |   14 +
 scripts/kconfirm/kconfirm-linux/src/lib.rs    |  129 ++
 scripts/kconfirm/kconfirm-linux/src/main.rs   |   74 +
 17 files changed, 3379 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/dev-tools/kconfirm.rst
 create mode 100644 scripts/kconfirm/Cargo.lock
 create mode 100644 scripts/kconfirm/Cargo.toml
 create mode 100644 scripts/kconfirm/Makefile
 create mode 100644 scripts/kconfirm/kconfirm-lib/Cargo.toml
 create mode 100644 scripts/kconfirm/kconfirm-lib/src/analyze.rs
 create mode 100644 scripts/kconfirm/kconfirm-lib/src/checks.rs
 create mode 100644 scripts/kconfirm/kconfirm-lib/src/dead_links.rs
 create mode 100644 scripts/kconfirm/kconfirm-lib/src/lib.rs
 create mode 100644 scripts/kconfirm/kconfirm-lib/src/output.rs
 create mode 100644 scripts/kconfirm/kconfirm-lib/src/symbol_table.rs
 create mode 100644 scripts/kconfirm/kconfirm-linux/Cargo.toml
 create mode 100644 scripts/kconfirm/kconfirm-linux/src/lib.rs
 create mode 100644 scripts/kconfirm/kconfirm-linux/src/main.rs

-- 
2.53.0